• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.437-443
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• 2024

The purpose of radiological Dispersal Device(RDD) is to kill people by explosives and to cause radiation exposure by dispersing radioactive materials. And It is a form of explosive that combines radioactive materials such as Co-60 and Ir-192 with improvised explosives. In this study, we tested and evaluated whether it was possible to read the internal structure of an explosive using X-rays in a radioactive explosive situation. The improvised explosive device was manufactured using 2 lb of model TNT explosives, one practice detonator, one 9V battery, and a timer switch in a leather briefcase measuring 41×35×10 cm³. The radioactive material used was the Co-60 source used in the low-level gamma ray irradiation device operated at the Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute. The radiation dose used was gamma ray energy of 1.17 MeV and 1.33 MeV from a Co-60 source of 2208 Ci. The dose rates are divided into 0.5, 1, 2, and 4 Gy/h, and the exposure time was divided into 1, 3, 5, and 10 minutes. Co-60 source was mixed with the manufactured explosive and X-ray image reading was performed. As a result of the experiment, the X-ray image appeared black in all conditions divided by dose rate and time, and it was impossible to confirm the internal structure of the explosive. This is because γ-rays emitted from radioactive explosives have higher energy and stronger penetrating power than X-rays, so it is believed that imaging using X-rays is limited By blackening the film. The results of this study are expected to be used as basic data for research and development of X-ray imaging that can read the internal structure of explosives in radioactive explosive situations.

• The Korean Journal of Emergency Medical Services
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• v.13 no.3
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• pp.41-58
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• 2009

Objective : The purpose of this study is to identify actual operations and issues of wireless paging system operation for the aged living alone as the end users of wireless paging system primarily in Gwangyang city, and thereby to explore possible advanced and integrated ways to promote social safety network for the aged. Methods : The survey tool used in this study was a structured questionnaire form consisting of question items. The researcher hereof conducted this survey by means of direct visit and interview during two seasons, i.e. from February to August, 2008 and from December 2008 to March 2009, respectively. Results : 1) For general demographic characteristics, it was found that 90.9% of all respondents were women and 61.2% of all respondents were at age 75 to 84. for health conditions, it was found that more than 90% of all respondents often took medicines due to their unhealthy body, and most of respondents suffered from musculoskeletal diseases 79.3% and circulatory diseases 61.6%. for walking capacity, it was found that 45.5% of all respondents used walking aids, and disable respondents (11.5% of all respondents) were represented primarily by those with physical disability (52.6% of disable respondents). for actual use of medical institutions, it was found 47.3% of all respondents relied on local clinics, since they preferred neighborhood hospitals or clinics they can trust for medical care. for social activities and supports, it was found that 43.6% respondents had 'needs for assistance at times' and 33.9% respondents have 'no need for assistance'. And it was found that the major difficulties in living alone at old age were represented primarily by health problems 37.8% and economic difficulties 33.5%. 2) For characteristics related to wireless paging system, it was found that 90.3% respondents used wireless paging system recommended by firemen, and 28.5% respondents used this system. and it was found that 59.6% respondents used this system once, and 85.2% respondents used it because of acute or chronic diseases. more than 90% respondents thought that they knew about wireless paging system and considered themselves safe, but 83.6% respondents didn't attach a remote control on their upper clothes, and even 49.1% respondents turned off the power of wireless paging system due to their concern about electricity bill and noise. 3) It was found that 83.6% respondents felt it necessary to use wireless paging system, and wireless paging users felt more satisfied with using the system than non-users, and 50.7% showed high satisfaction at certain psychological benefits like 'confidence in coping with critical situations' and 'a sense of relief'. In addition, it was found that some respondents who answered that 'they didn't turn off the paging system as they knew how it works' and those who answered that they knew 'how to use it' showed relatively high satisfaction. And some respondents who kept it well and felt it necessary also showed high satisfaction. 4) It was found that the level of satisfaction our respondents felt with using wireless paging system varied significantly availability($x^{2}$ = 12.759, p = .002), psychological advantages($x^{2}$ = 12.174, p = .002), knowledge about how to use system($x^{2}$ = 7.021, p = .016), power on/off($x^{2}$ = 13.221, p = .001), level of knowledge about system($x^{2}$ = 21.002, p = .000), maintenance($x^{2}$ = 9.871, p = .007) and level of necessity($x^{2}$ = 34.939, p = .000) on the statistical basis.

• Journal of Distribution Science
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• v.12 no.4
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• pp.31-39
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• 2014

Purpose - This study investigates the following two issues. First, we attempt to find the important determinants of housing investment and to identify their significance rank using survey panel data. Recently, the expansion of global uncertainty in the real estate market has directly and indirectly influenced the Korean housing market; households demonstrate a sensitive reaction to changes in that market. Therefore, this study aims to draw conclusions from understanding how the impact of financial strength of the household is related to house investment. Second, we attempt to verify the effectiveness of diverse indices of financial strength such as DTI, LTV, and PIR as measures to monitor the housing market. In the continuous housing market recession after the global crisis, the government places top priority on residence stability. However, the government still imposes forceful restraints on indices of financial strength. We believe this study verifies the utility of these regulations when used in the housing market. Research design, data, and methodology - The data source for this study is the "National Survey of Tax and Benefit" from 2007 (1st) to 2011 (5th) by the Korea Institute of Public Finance. Based on this survey data, we use panel data of 3,838 households that have been surveyed continuously for 5 years. We sort the base variables according to relevance of house investment criteria using the decision tree model (DTM), which is the standard decision-making model for data-mining techniques. The DTM method is known as a powerful methodology to identify contributory variables for predictive power. In addition, we analyze how important explanatory variables and the financial strength index of households affect housing investment with the binary logistic multi-regressive model. Based on the analyses, we conclude that the financial strength index has a significant role in house investment demand. Results - The results of this research are as follows: 1) The determinants of housing investment are age, consumption expenditures, income, total assets, rent deposit, housing price, habits satisfaction, housing scale, number of household members, and debt related to housing. 2) The impact power of these determinants has changed more or less annually due to economic situations and housing market conditions. The level of consumption expenditure and income are the main determinants before 2009; however, the determinants of housing investment changed to indices of the financial strength of households, i.e., DTI, LTV, and PIR, after 2009. 3) Most of all, since 2009, housing loans has been a more important variable than the level of consumption in making housing market decisions. Conclusions - The results of this research show that sound financing of households has a stronger effect on housing investment than reduced consumption expenditures. At the same time, the key indices that must be monitored by the government under economic emergency conditions differ from those requiring monitoring under normal market conditions; therefore, political indices to encourage and promote the housing market must be divided based on market conditions.

• Progress in Medical Physics
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• v.18 no.3
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• pp.144-148
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• 2007

Current digital radiography systems are rapidly glowing in clinical applications. The purpose of this study was to evaluate the characteristics of a mobile digital radiographic system. The performance of the mobile DR system was evaluated by measuring the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Measurements were made on a LISTEM Mobix-1000 generator and a Teleoptic PRA Alpha-R4000 detector. Imaging characteristics were measured for these two systems using the IEC-61267 defined RQA5 (kVp: 74, additional filtration: 21 mmAl) radiographic condition. The MTF at 10% was measured as 2.4 cycles/mm and the DQE(0) values for radiation exposure 0.19, 0.5, and 1.3 mR were measured as 54%, 55%, and 76%, respectively. The NPS curves gradually decreased at high spatial frequencies. This high DQE at low frequencies, may be useful for low frequency information. The results suggested that mobile DR system could be integrated with emergency ambulance system in teleradiologic imaging applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.81-89
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• 2002

The Battery Energy Storage System (BESS) has lots of advantages such as load leveling, quick response emergency power (spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission construction. However, it is very critical that economic feasibility requires justification from the customer side of meter to promoting the dissemination of BESS in nation widely. In this paper, we proposed the economic assessment model of customer owned BESS which is complemented and improved the existing model. The proposed model is applied to the typical customer types, i.e. light industrial, commercial, and residential, which are taken from the statistical analysis on the load profile survey of Korea Electric Power COmpany (KEPCO). The economic viability performed for each customer load type to justifying their economic feasibility of BESS installation from the economic measures such as payback period, Net Present Worth (NPW), Rate Of Return (ROR). The results show that the BESS has economic benefits to the specific customer type, i.e. residential customer. Therefore, the government and the energy agency should be committing the support program, such as tax incentive, financial support, to disseminate the BESS nation widely. The results of this paper are useful to the customer investment decision-making and the national energy policy & strategy in Korea.

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.639-648
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• 2009

Earth's environment issues are introduced recently and every year the social loss have been occurred by the impact of various disaster. This kind of disaster and weather problems are the increasing reason of electricity transmission network equipment's failures because of exposing by the natural environment. The emergency and abnormal status of electricity equipment make the power outage of manufacturing plant and discomfort of people's lives. So, to protect the electricity equipment from the natural disasters and to supply the power to customer as stable, the supporting systems are required. In this paper, the research results are described the development process and the outcomes of the real-time natural disaster failure analysis information system including the describing about the impact of disaster and weather change, making the natural weather information, and linking the realtime monitoring system. As of development process, according to application development methodology, techniques are enumerated including the real time interface with related systems, the analysing the geographic information on the digital map using GIS application technology to extract the malfunction equipment potentially and to manage the equipments efficiently. Through this system makes remarkable performance it minimize the failures of the equipments, the increasing the efficiency of the equipment operation, the support of scientific information related on the mid-term enhancement plan, the savings on equipment investment, the quality upgrading of electricity supply, and the various supports in the field.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.68-73
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• 2013

In this paper, we proposed a readout circuit of pulse waveform and rate for a U-health system to monitor health condition. For long-time operation without replacing or charging a battery, either pulse waveform or pulse rate is selected as the output data of the proposed readout circuit according to health condition of a user. The proposed readout circuit consists of a simple digital logic discriminator and a dual-mode ADC which operates in the ADC mode or in the count mode. Firstly, the readout circuit counts pulse rate for 4 seconds in the count mode using the dual-mode ADC. Health condition is examined after the counted pulse rate is accumulated for 1 minute in the discriminator. If the pulse rate is out of the preset normal range, the dual-mode ADC operates in the ADC mode where pulse waveform is converted into 10-bit digital data with the sampling frequency of 1 kHz. These data are stored in a buffer and transmitted by 620 kbps to an external monitor through a RF transmitter. The data transmission period of the RF transmitter depends on the operation mode. It is generally 1 minute in the normal situation or 1 ms in the emergency situation. The proposed readout circuit was designed with $0.11{\mu}m$ process technology. The chip area is $460{\times}800{\mu}m^2$. According to measurement, the power consumption is $161.8{\mu}W$ in the count mode and $507.3{\mu}W$ in the ADC mode with the operating voltage of 1 V.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.25-35
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• 2013

This study examined 24 right-handed amateur baseball players. Twelve who had played baseball for more than 6 years were grouped as skilled players, while 12 who had played for 1-3 years were the unskilled player group. The swing motion was divided into four event phases: stance, backswing, impact, and follow-through. The mean and maximum plantar pressure, center of pressure, and ground reaction force were measured during each event phase. The mean and standard deviations for each variables were calculated and differences were validated with the independent sample t-test. A p-value <0.05 was considered statistically significant. The results were as follows. 1)The ideal stance is a stable, balanced position with more than 65% of weight on the right foot. There was significant difference in mean left plantar pressure, while the maximal plantar pressure and mean right plantar pressure did not differ significant. 2)The effective backswing of a skilled player is comprised a rightward shift in weight to build maximum energy. More than 90% of the weight was on the right foot. There was a significant difference in the mean left plantar pressure, while the maximal plantar pressure and mean right plantar pressure did not differ significantly. 3) For an effective impact, a rapid shift in weight to the left foot is essential, so that a power hit is obtained. Significant difference in the mean and maximum plantar pressures of both feet were observed. 4)Follow-through requires wight balance, more on the right than the left, without leaning leftward. There was no significant difference in the mean or maximum plantar pressure. 5)The center of plantar pressure should move from the center of the foot to the toe. 6)The analyses of the ground reaction force suggest that a good swing involves a gradual shift in weight to the right side and a rapid leftward shift at impact. Good balance, with the center of gravity on the right side at follow-through, is also required.

• Child Health Nursing Research
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• v.6 no.3
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• pp.372-386
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• 2000

The purpose of this study was to provide basic data on preschool children for accident prevention and improve their health through sound, safe living environment with safety education established through more systematic method. Data were collected from 300 preschoolers(150 preschooler are assigned to experimental group and 150 preschoolers are assigned to control group) from 4 to 6 years old using APP paper test which consists of questions and drawings. To experimental group, safety education were done 4 times within the time of 30 minutes per 1 time using education books, video, OHP, slide. The findings of this study are as follows: 1. There were significant difference in behavioral character between experimental group and control group(χ2=11.690, p= 0.003). So, safety education have effect on the behavioral character of preschooler. 2. In the accident proneness on preschooler between experimental group and control group according to general characteristics, it proved significant difference in the case of accident prevention education were done, movement stability(χ2=8.844, p=0.012) and behavioral character(χ2=6.699, p=0.035), in the case of housing pattern is mixed-type, behavioral character(χ2=10.37, p=0.006), in the case of subjects' age is 4 years old, watchfulness(χ2=9.525, p=0.009), in the case of subjects' age is 5 years old, behavioral character(χ2=7.324, p=0.026), in the case of children's order is second, behavioral character(χ2=14.31, p=0.001), in the case of children's sex is boy, living safety(χ2=7.981, p=0.018), movement speed (χ2=6.661, p=0.036), bihavioral character(χ2=8.837, p=0.012), in the case of children's sex is girl, reasoning power(χ2 =9.78, p=0.008), in the case of childrens have no past accidental experience, behavioral character(χ2=9.862, p=0.007), in the case of nuclear family, movement speed(χ2=6.341, p=0.042) and behavioral character(χ2=9.326, p=0.009), in the case of mothers' age is under thirty behavioral character(χ2=16.40, p=0.000), in the case of mothers' school career is under high school graduate, behavioral character(χ2 =8.375, p=0.015), in the case of mothers' school career is beyond college graduate, reasoning power(χ2=9.803, p=0.007) and behavioral character(χ2=6.205, p=0.045), in the case of mothers' job is part time, movement speed(χ2=10.99, p=0.004), in the case of mothers have no job, movement stability(χ2=8.490, p=0.014) and behavioral character(χ2=10.11, p=0.006). The difference of accident proneness between experimental group and control group according to general characteristics, it also showed that there were significant difference in behavioral character compared to other area.. From this findings, we can guess that safety education change and guide preschoolers' behavioral character to desirable direction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.319-330
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• 2016

Recently, 3D printing technology has been applied to make a concept model and working mockup of an industrial application. On the other hand, this technology has limited applications in industrial products due to the materials and reliability of the 3D printed product. In this study, the components of a full cord switch module are proposed as a case of a 3D printed component that can be used as a substitute for a short period. These are hub-driven and lever lockup components that have the structural characteristics of breaking down frequently in the emergency operating status. To ensure the structural strength for a substitute period, research of structure optimization was performed because 3D printing technology has a limitation in the materials used. After optimizing the structure variables of the hub-driven component, reasonable results can be drawn in that the safety factors of the left and right switching mode are 1.243 (${\Delta}153.67%$) and 3.156 (${\Delta}404.96%$). The lever lockup component has a structural weak point that can break down easily on the lockup-part because of a cantilever shape and bending moment. The rib structure was applied to decrease the deflection. In addition, optimization of the structural variables was performed, showing a safety factor of 7.52(${\Delta}26%$).