Patent Application
20180052239
The present invention relates to a method for recognizing activity of a wearer by using a motion sensor in a personal radiation dosimeter, and more specifically, to a data processing method of a personal radiation dosimeter to recognize whether a wearer normally wears a radiation dosimeter, to recognize work behavior of the wearer by integrally analyzing radiation measurement data and motion data of the wearer, and to recognize activity of the wearer by using a motion sensor value helpful to improvement of work behavior and improvement of radioactive danger recognition of the wearer on the basis thereof.
Radioactivity means the number of nuclear changes per unit time, and the unit thereof is Becquerel (Bq) or Curie (Ci). 1 Becquerel means that one nuclear conversion occurs every second in a substance. In radioactivity, attenuation occurs as time passes, and a half-life means the time for initial radioactivity to be reduced in half. As described above, radioactive decay occurs while radioactivity is attenuated. In this case, particles or electromagnetic energy flow emitted from atoms or atomic nucleuses are radiation. The radiation is classified into alpha-ray, beta-ray, gamma-ray, X-ray, electron-ray, proton, neutron-ray, and the like. The radiation presents various physical characteristics such as energy intensity and permeability in accordance with the type of radiation, and may have a harmful influence on a human body. Even when a human body is exposed to a same amount of radiation-absorbed dose, health risks are different in accordance with the type and energy of radiation at the time of irradiation to the human body. Accordingly, a radiation dose obtained by correcting an absorbed dose by reflecting biological effects is represented by a unit such as Sievert (Sv) or rem. 1 Sv is 100 rem. Globally, an annual average radiation exposure of general people is 2.4 mSv, and according to the causing substance, radon (55%), in-body radiation (11%), perceptual radiation (8%), spaceship (8%), and the like are referred to as natural radiation, and diagnostic X-ray (11%), therapeutic radiation (4%), consumer goods (3%), and the like are referred to as artificial radiation. When exposure to artificial radiation in addition to exposure to such natural radiation is excessive, the radiation harms the human body. Therefore, a radiation dose limit is determined and managed by law from the government such that exposure of general people does not exceed 1 mSv per year and exposure of radiation workers does not exceed 50 mSv per year. However, medical exposure is increasing, for example, exposure of one medical CT scan is 6.9 mSv exceeding an annual allowance limit. Accordingly, social risk is also increasing. In the case of the United States, in 1980, an annual individual average exposure dose was 3.6 mSv, and 0.8 mSv thereof was medical exposure. However, in 2006, an annual individual average exposure dose was increased to 6 mSv, 4.5 mSv thereof was medical exposure, and it can be seen that medical exposure had increased five times or more in 26 years.
Workers in nuclear handling institutions such as medical institutions, nuclear power plants, and nuclear research institutes have to obligatorily wear a personal radiation dosimeter by law, and are managed by the government to prevent an accident caused by radiation exposure. The personal radiation dosimeter is generally referred to as a thermo luminescent dosimeter (TLD), and measures post accumulation by the unit of several months. Since the thermo luminescent dosimeter cannot perform real-time measurement, real-time measurement dosimeters referred to as a personal radiation dosimeter (PRD) have been subsidiarily used in the industrial field, but are not spread to the industry due to factors such as a large volume, a high price, and inaccuracy of measurement.
The conventional thermo luminescent dosimeter is a badge type measurement tool which measures radiation by using a phenomenon that a thermoluminescence substance absorbs energy when receiving radiation, and emits energy in the type of light again while collected electrons break away when heat is applied. It is a personal radiation measurement tool which is enforced by law to radiation workers working in most of the world medical institutions and industrial field and is most widely used. However, the thermo luminescent dosimeter cannot perform real-time measurement. A professional measurement company collects thermo luminescent dosimeters in the period of 2 to 3 months and executes work for measurement, and only post accumulation is figured out. Accordingly, since it cannot be known when, where, and how a radiation worker is exposed, it does not help supporting safety of a worker, improving behavior and consciousness of a worker, and actively managing exposure.
Portable personal radiation dosimeters (PRD) are spreading to solve problems of the thermo luminescent dosimeters. Since it is a personal measurement device, it is a portable size, and it is possible to measure a radiation dose in real time, to display it on a display, to warn with an alarm in case of emergency or when a radiation dose equal to or more than an expected value is measured, and to help taking immediate protective action. However, the personal radiation dosimeter (PRD) is expensive, being more than thousands of dollars, and has large financial burden for all radiation workers to wear. A person can carry the personal radiation dosimeter (PRD), but the personal radiation dosimeter (PRD) is relatively large, and is not suitable to wear. There is also complicacy in management such as battery replacement. Thus, the personal radiation dosimeter (PRD) is not widely spread, and is not suitable to systemically manage and monitor an exposure dose. In addition, the personal radiation dosimeter (PRD) is not a device which has to be obligatorily worn by law, and is ignored in the field.
Since both of the thermo luminescent dosimeter (TLD) and the personal radiation dosimeter (PRD) have no communication function, the measured radiation dose cannot be transmitted to a control server. Individual exposure data cannot be accumulated due to such defects, and there is no way to find out meaningful improvement measures in exposure data. In addition, they are provided with only a radiation measurement sensor therein, so it may be possible to find out radiation dose data, but exposure data associated with behavior of a worker cannot be extracted because there is no motion sensor.
The present invention has been made in consideration of such problems, and is to provide a data processing method of a personal radiation dosimeter which couples real-time radiation dose measurement data with motion sensor data, transmits the data to a control server by using a communication device, provides a work improvement method of a radiation worker through real-time and cumulative time radiation doses of a worker and behavior pattern analysis, and can recognize activity of a wearer by using a motion sensor value helping safety of a radiation worker.
A data processing method of a personal radiation dosimeter to recognize activity of a wearer by using a motion sensor value according to the present invention to achieve the objects described above includes steps of: detecting a value of a radiation sensor provided with a dosimeter; generating a movement value by a value of the motion sensor provided in the dosimeter; generating a shock value which is a change value of a gravity axis from the value of the motion sensor provided in the dosimeter; generating a measurement time in a clock sensor provided in the dosimeter; coupling data values of the sensors into one-packet data; transmitting the packet data to a control server through a communication device; and extracting a motion state in radiation work environment of a dosimeter wearer on the basis of the radiation sensor value and motion sensor value of the packet data.
The motion sensor may be a 3-axis accelerometer.
The data processing method of a personal radiation dosimeter may further include a step of issuing an alert when downward shock occurs in a high-level radioactive status on the basis of the shock value and the radiation sensor value.
The data processing method of a personal radiation dosimeter may further include a step of comparing an activity time with a stop time to determine whether a dosimeter is worn.
The data processing method of a personal radiation dosimeter may further include a step of determining a case where the movement value is an activity state at the time without a work history of a worker and the radiation sensor value is equal to or more than a reference value, as use by others.
The communication device may use any one of ZigBee communication, Bluetooth communication, Wi-Fi communication, and low power wide area network (LPWAN).
In addition, the present invention provides means which couples radiation detection data detected by a radiation sensor, motion data of a worker detected by a motion sensor, and measurement time data, and transmits the data to a control server by using a wired or wireless communication device, wherein the server extracts behavior of a worker, to generate methods for improving a working method and promoting safety consciousness.
Specifically, a risk range of real-time radiation measurement is classified into safety, caution, warning, and the like, and the motion data of the motion sensor is classified into stop and activity, and is interlocked with a measurement time. Particularly, real-time measurement and alarm are possible at the time of high-level radiation exposure, and a real-time shock detection function using change in gravity axis of the motion sensor is provided. The present invention provides specific means for comparing the cumulative radiation dose data and motion data with an activity history of a worker to improve work behavior of a worker.
Hereinafter, in order to describe the present invention in detail to the extent that those skilled in the art can easily carry out the present invention, the most preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
A radiation dose measurement device according to the present invention is referred to as a wearable personal radiation dosimeter (WPRD) for distinction from a thermo luminescent dosimeter (TLD) and a personal radiation dosimeter (PRD). The wearable personal radiation dosimeter (WPRD) is a small wearable personal radiation dosimeter which embodies all of merits of small size and low price of the conventional thermo luminescent dosimeter (TLD) and merits of real-time measurement, alarm, and communication function of the conventional personal radiation dosimeter (PRD).
Herein, a motion sensor which cannot be seen in the conventional dosimeters is attached to recognize movement of a worker. The hardware of the wearable personal radiation dosimeter (WPRD) is wearable, and uses a battery 101 as a power source. A power supply unit 102 which controls charge and discharge of the battery 101 is provided, and a potential sensor 114 which measures a battery level is provided to let a user know a charging moment. The conventional thermo luminescent dosimeter (TLD) does not need an electronic circuit, and thus does not need a central processing unit 112 or a power supply unit 102. However, the conventional personal radiation dosimeter (PRD) uses an electronic circuit, and thus the central processing unit 112 and the power supply unit 102 are essential. The central processing unit 112 takes charge of all controls and determinations of the wearable personal radiation dosimeter (WPRD), and a memory 108 is a device which stores measurement data and execution data. The memory 108 stores measurement data until the measurement data is transmitted to a control server 207 by using wired communication 103 or wireless communication 105. As the memory 108 gets larger, more data can be accumulated and stored.
A radiation sensor 106 is a device which measures a radiation dose as a key component of a radiation dosimeter. The radiation sensor 106 may be classified into GM counter, ionization chamber, semiconductor detector, scintillator, and the like according to the type of radiation measurement. Although any measurement-type sensor can be used as the radiation sensor 106 of the present invention, the scintillator-type radiation sensor is most preferable in comprehensive consideration of size, current consumption, measurement reliability, and the like. The radiation sensor 106 has to be able to measure 0.1 uSv/Hr or less, which is a natural radiation dose, and has to be able to measure various kinds of radiation and energy such as beta-ray, gamma-ray, X-ray, and neutron depending on usage. Particularly, the radiation sensor 106 has to be operated by a battery, and a characteristic of low current consumption is essential.
A motion sensor 113 is a sensor for recognizing movement by using a principle of
A clock 109 is necessary to know an accurate measurement time. Sensor data processed in the wearable personal radiation dosimeter (WPRD) are three kinds of potential, radiation dose, and motion, and meaningful behavior analysis is possible only when an accurate measurement time of the data is known. Accordingly, a clock 109 having characteristics of a real-time block generator has to be used. An input unit 110 is a device for user inputs such as user setting, alarm-off, and display operation, and may be a button switch or the like. A display 111 is a device which outputs various kinds of information for user convenience such as output of a measurement result, output of various kinds of messages, and confirmation of an operation state, and may be a display 111 having an advanced function such as an LCD. However, a simple display 111 such as an LED may be more suitable in consideration of restrictions of wearable type, low power, and the like. An alarm 107 is a device which generates an alarm for announcing an emergency situation such as high-level radiation exposure and falling-down of a worker. The alarm 107 may generate an alarm in forms of sound, light, vibration, and the like.
A wireless communication unit 103 is a wireless communication device for transmitting various kinds of data of the wearable personal radiation dosimeter (WPRD) to a control server 207, and a terminal such as a smartphone 202 or a note pad 203 provided outside. Wireless communication technology may be short-range wireless communication technology such as IEEE 802.15.1 Bluetooth communication technology, IEEE 802.15.4 ZigBee communication technology, and IEEE 802.11 Wi-Fi, lower power wide area network (LPWAN) technology such as SigFox and LoRa, or wireless communication technology using ISM bands of 400 MHz, 800 MHz, and 900 MHz. In addition, mobile communication (cellular network) technology such as 3G/4G may be used. An antenna 104 is a device which radiates a transmission and reception RF signal of the wireless communication unit 103 into the air. The wearable personal radiation dosimeter (WPRD) has wearable characteristics, and it is practical to design the antenna to an intenna. The wireless communication unit 103 and the antenna 104 may have an influence on a radiation measurement result of the radiation sensor 106 due to interference based on RF wireless signals. Accordingly, the wireless communication unit 103 and the radiation sensor 106 have to be designed such that a mutual interference phenomenon does not occur by thoroughly separating them in circuit. The wired communication unit 105 is a device for transmitting and receiving data to and from the outside by using wired communication such as USB, Serial, and Ethernet. Considering characteristics of the wearable personal radiation dosimeter (WPRD), it is general that the wireless communication unit 103 is a primary communication channel, and the wired communication unit 105 is a secondary communication channel.
Movement in the 3-axis accelerometer means a change value of each of X, Y, and Z axes. It is represented by Math 1.
Subtracting 1 only from the Y axis (y−1) is to correct a phenomenon that acceleration of gravy of 1 g always acts in the Y axis as described above. Summing from t=0to 59 is a process for conversion into movement of the unit of minute by summing motion sensor values detected by the unit of second for 60 seconds because a message is defined such that various kinds of sensor extraction units of the wearable personal radiation dosimeter (WPRD) 201 are the unit of minute. If the basic time unit is changed, the cumulative time of movement, radiation dose, and the like have to be changed together according thereto. The reason why the value of each axis is squared and added as illustrated in Math 1 is to obtain only a movement change value in disregard of movement directionality. In application separately requiring a change value for each axis, only the value of each axis may be separately extracted and used.
Shock in the 3-axis accelerometer means a change value of the Y axis. It is represented by Math 2.
√{square root over (y2)} [Math 2]
As seen here, only the Y axis is used for shock detection. There is no adding process to convert a sensor change value from the unit of second into the unit of minute. Since shock temporarily occurs for a short time of 1 second or less in the Y axis, it is designed in consideration of such characteristics of shock. However, differently from other data applied by the unit of minute, a system designer has to keep in mind that a shock value has to be applied by the unit of second. As described above, since the momentary up and down movement change value of the Y axis is a shock value, the appearance of the wearable personal radiation dosimeter (WPRD) 201 has to be designed such that the Y axis is directed up and down. The reason why the Y axis is set to the shock value is that the Y-axis value is rapidly changed in case of fainting or falling down due to shock when movement characteristics of a radiation worker is analyzed. If other movement characteristics of a worker are interpreted as shock, the other value suitable there has to be used.
The process data field can be extracted from a reference table illustrated in
It is possible to set determination criteria of an analysis program 205 and a warning program 206 of the control server 207 on the basis of various kinds of sensor data extracted in the wearable personal radiation dosimeter (WPRD) 201 illustrated in
Whether a radiation worker wears a wearable personal radiation dosimeter (WPRD) 201, a wearing time, and the cumulative radiation dose at the time of wearing can be extracted from the database illustrated in
Herein, the total cumulative radiation dose is represented by Math 3.
Total cumulative radiation dose=Stop cumulative radiation dose+Activity cumulative radiation dose
=(Temporary stop cumulative radiation dose+Long-time stop cumulative radiation dose)+activity cumulative radiation dose [Math 3]
In other words, as represented in Math 3, the total cumulative radiation dose is acquired by summing the stop cumulative radiation dose and the activity cumulative radiation dose, and the stop cumulative radiation dose is the sum of the temporary stop cumulative radiation dose and the long-time stop cumulative radiation dose. Herein, various cases capable of determining whether the personal radiation dosimeter is lawfully worn can be estimated. First, when the activity cumulative time is significantly shorter than that of a personal work log, it is possible to estimate the fact that the radiation worker worked without wearing the dosimeter, which is a violation of regulations. Second, when there is no work in the work log and the activity cumulative time is detected, it is possible to estimate the fact that the other worker wore the dosimeter and worked, which is a violation of regulations. Third, when the long-time stop cumulative radiation dose is excessively higher than that of the other worker, it is estimated that a space for storing the dosimeter or a rest space of workers is excessively exposed to radiation, and thus it is determined that safety measures for this is needed. Fourth, when the temporary stop cumulative radiation dose is excessively higher than that of the other worker, it means that a rest time of the worker for a while is long in the high-level radiation environment. Accordingly, it is necessary to train the worker to improve the work behavior to quickly finish the work, and be out of the high-level radiation environment. Fifth, when the total cumulative radiation dose is excessively higher than that of the other worker, the cause thereof should be understood to improve the work environment or to move the work to non-radiation environment, and thus to manage the radiation dose not to be over the annual allowable exposure value. As described above, when the movement value and the radiation dose are recorded and compared simultaneously, it is possible to understand various kinds of work environments and activities of the radiation worker, and thus it is possible to contribute to safety of the radiation worker.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2016-0105998 | Aug 2016 | KR | national |
This application claims priority to Korean Patent Application No. 10-2016-0105998, filed Aug. 22, 2016, the entire content of which is incorporated herein by reference.
