• 한국콘텐츠학회논문지
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• 제14권11호
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• pp.355-361
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• 2014

본 연구의 목적은 필름/증감지 방식에서 사용된 비감도 측정 방식을 이용하여 컴퓨터 방사선영상에서 영상판의 상대적 발광량을 평가하고자 하였다. 비감도 측정을 위한 특성곡선은 균일한 알루미늄으로 구성된 11 계단의 투과도계를 이용하였다. 디지털 방사선영상을 획득하기 위한 X선 조사조건은 50 kVp, 10 mAs로 조절했다. 영상후처리 알고리즘(MUSICA)의 모든 파라메터들은 제로화하여 원본 데이터에 근사화하였고 레이저 조사분류(exposure class)는 200으로 고정하였다. 영상판의 상대적 발광량 모델링은 X선 조사후 0, 4, 8, 12, 24 시간 보관한 영상판을 이용하였다. 그 결과, 컴퓨터 방사선영상시스템의 영상판 비감도 측정에 필요한 감도점 농도는 모든 특성곡선을 상대적으로 측정하기 용이한 2000 픽셀(pixel) 값이 적합하였다. 또한 영상판의 비감도가 저하될 때 영상신호를 생성하기 위한 빛 발광량도 감소하였다. 본 연구에서 제시한 비감도 평가방법은 컴퓨터 방사선영상시스템에서 영상판의 상대적 발광량을 평가할 수 있는 기술로 활용될 수 있을 것이다.

• 대한방사선기술학회지:방사선기술과학
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• 제41권5호
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• pp.437-444
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• 2018

Whole-Body counters have been used to evaluate the internal contamination of gamma emitting radionuclides. Among the whole-body counters used in domestic nuclear facilities, Fastscan made by CANBERRA contains 2 NaI(Tl) detectors and is generally used to monitor the primary internal exposure. It has the advantage of achieving MDA even with short time measurements. Accuscan is a bed type, and has good energy resolution because it is composed of HPGe detector. Since the Accuscan with better energy resolution than Fastscan has better able to identify radionuclides, it is used to monitor secondary internal exposure. Some nuclear facilities have only Fastscan. We analyzed statistically whether Fastscan is enough to ensure accuracy and precision comparing with Accuscan. To do this, we prepared a CRM created by the Korea Research Institute of Standards and Science. We also obtained the data of 6 Fastscans and 5 Accuscans in domestic nuclear facilities. As a result of the study, although Fastscan compared with Accuscan is not as accurate as the Accuscan, the precision is statistically same. However, accuracy of Fastscan is in compliance with international standards except low energy range. In terms of accuracy and precision except radionuclides emitting low energy, it is possible to measure radioactivity inside workers even in nuclear facilities where only Fastscan is used.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
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• pp.290-300
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• 2000

One of the most important topics in attentional and emotional modulation of cardiac responses is time course of cardiac chronotropic response. The reason lies in dual innervation of heart, which leads to occurrence of several phases of cardiac response during exposure to affective stimuli, determined by the balance of sympathetic and parasympathetic influences. Cardiac chronotropic reactivity thus represents quite effective measure capable to trace the moment when attending and orienting processes (i.e., sensory intake of stimulus) prime relevant behavioral response (ile., emotion with approach or avoidance tendencies). The aim of this study was to find the time course of heart rate (HR) responses typical for negative (disgust, surprise, fear, anger) and positive (happiness, pleasant erotic) affective pictures and to identify cardiac response dissociation for emotions with different action tendencies such as "approach" (surprise, anger, happiness) and "avoidance" (fear, sadness, disgust). Forty college students participated in this study where cardiac responses to slides from IAPS intended to evoke basic emotions (surprise, fear, anger, sadness, disgust, happiness, pleasant-erotic). Inter-beat intervals of HR were analyzed on every 10 sec basis during 60 sec long exposure to affective visual stimuli. Obtained results demonstrated that differentiation was observed at the very first 10s of exposure (anger-fear, surprise-sad, surprise-erotic, surprise-happiness paris), reaching the peak of dissociation at 30s (same pairs plus surprise-disgust and surprise-fear) and was still effective for some pairs (surprise-erotic, surprise-sad) even at 50s and 60s. discussed are potential cardiac autonomic mechanisms underlying attention and emotion processes evoked by affective stimulation and theoretical considerations implicated to understand the role of differential cardiac reactivity in the behavioral context (e.g., approach-avoidance tendencies, orienting-defense responses).

• Journal of Ecology and Environment
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• 제35권3호
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• pp.203-212
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• 2012

The physiological effects of elevated $CO_2$ concentration and temperature were examined for Quercus gilva and Q. glauca grown under control (ambient $CO_2$ and temperature) and treatment (elevated $CO_2$ and temperature) conditions for 39 months. The objective of the study was to measure the long-term responses, in physiological parameters, of two oaks species exposed to elevated $CO_2$ and temperature. The photosynthetic rate of Q. gilva was found to be decreased, but that of Q. glauca was not significantly affected, after long-term exposure to elevated $CO_2$ and temperature. Stomatal conductance of Q. glauca was reduced by 21.7%, but that of Q. gilva was not significantly affected, by long-term exposure to $CO_2$ and temperature. However, the transpiration rate of the two oak species decreased. Water use efficiency of Q. gilva was not significantly affected by elevated $CO_2$ and temperature, while that of Q. glauca was increased by 56.6%. The leaves of Q. gilva grown under treatment conditions had an increased C:N ratio due to their reduced nitrogen content, while those of Q. glauca were not significantly affected by long-term exposure to elevated $CO_2$ and temperature. These results suggest that the long-term responses to elevated $CO_2$ and temperature between Q. gilva and Q. glauca are different, and that Q. gilva, the endangered species, is more sensitive to elevated $CO_2$ and temperature than Q. glauca.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.808-813
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• 2011

There are hundreds of thousands call center workers wearing acoustic device. However, researches and noise exposure measurements on the noise transmitted from acoustic devices have seldom been performed due to the difficulty of measurement and to the absence of the measuring method in Korea. The aim of this study is to set up management measures to protect hearing loss on the call operator by acquiring measurement data of noise transmitted from the headset Noise exposure measurements of 17 operators were performed in 7 call centers and Head and Torso Simulator method in compliance with the ISO Standard 11904-2 was used for the measurement of noise transmitted from the headset Sound pressure levels(SPL) transmitted from the headset were 73.2~86 dB(A). The operator exposed to the highest SPL set up his volume control at 9 which was the highest volume level. The volume control level, adjustable from 1 to 9, could be identified 12 out of 17 operators and the range of volume levels was 4.5~9. As a result of Pearson Correlation Analysis, the correlation between volume level and SPL transmitted from the headset showed high relation as significance at the 0.672 level(p<0.05). To protect hearing loss of call center operators, it is more practical and effective measure to limit the volume level below the noise exposure level, i.e. 85 dB(A), rather than to carry out noise monitoring considering cost-effective aspect.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.430-430
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• 2007

In this study, the nematic liquid crystal (NLC) alignment effects treated on the ZnO thin film layers using ion beam irradiation were successfully studied for the first time. The ZnO thin films were deposited on indium-tin-oxide (ITO) coated glass substrates by rf-sputter and The ZnO thin films were deposited at the three kinds of rf power. The used DuoPIGatron type ion beam system, which can be advantageous in a large area with high density plasma generation. The ion beam parameters were as follows: energy of 1800 eV, exposure time of 1 min and ion beam current of $4\;mA/cm^2$ at exposure angles of $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. The homogeneous and homeotropic LC aligning capabilities treated on the ZnO thin film surface with ion beam exposure of $45^{\circ}$ for 1 min can be achieved. The low pretilt angle for a NLC treated on the ZnO thin film surface with ion beam irradiation for all incident angles was measured. The good LC alignment treated on the ZnO thin film with ion beam exposure at rf power of 150 W can be measure. For identifying surfaces topography of the ZnO thin films, atomic force microscopy (AFM) was introduced. After ion beam irradiation, test samples were fabricated in an anti-parallel configuration with a cell gap of $60{\mu}m$.

• 한국소음진동공학회논문집
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• 제21권7호
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• pp.615-621
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• 2011

There are hundreds of thousands call center workers wearing acoustic device. However, researches and noise exposure measurements on the noise transmitted from acoustic devices have seldom been performed due to the difficulty of measurement and to the absence of the measuring method in Korea. The aim of this study is to set up management measures to protect hearing loss on the call operator by acquiring measurement data of noise transmitted from the headset. Noise exposure measurements of 17 operators were performed in 7 call centers and head and Torso simulator method in compliance with the ISO standard 11904-2 was used for the measurement of noise transmitted from the headset. Sound pressure levels(SPL) transmitted from the headset were 73.2~86 dB(A). The operator exposed to the highest SPL set up his volume control at 9 which was the highest volume level. The volume control level, adjustable from 1 to 9, could be identified 12 out of 17 operators and the range of volume levels was 4.5~9. As a result of pearson correlation analysis, the correlation between volume level and SPL transmitted from the headset showed high relation as significance at the 0.672 level(p<0.05). To protect hearing loss of call center operators, it is more practical and effective measure to limit the volume level below the noise exposure level, i.e. 85 dB(A), rather than to carry out noise monitoring considering cost-effective aspect.

• 한국방사선학회논문지
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• 제1권3호
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• pp.5-10
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• 2007

복부 단순방사선 촬영은 흉부촬영에 이어 가장 많이 검사가 이루어지고 있는 실정인 것이 임상현장이므로 환자의 피폭선량에 대한 연구가 필수적으로 진행이 이루어 질 필요성이 대두가 된다. 그 결과는 다음과 같았다. 1. 관전압이 60-85kV 증가 시 표면선량은 증가하고, 촬영거리를 50-150cm로 20cm씩 증가함에 mAs도 증가시킨 결과 표면선량은 감소되었다. 2. 심부선량 백분율은 60-75kV에서는 4cm 깊이, 80-85kV에서는 6cm 깊이에서 50% 이하를 나타내었으며, 60kV에서는 12cm 깊이, 65-85kV에서는 14cm 깊이에서 5% 이하를 나타났다. 3. 전방산란율은 60-85kV까지 관전압이 증가 시 10-11.78%까지 증가함을 나타내었다. 후방 산란율은 관전압이 60-85kV 증가 시 25-37%로 증가하였다. 측방산란율은 음극 측에서는 관전압이 60-85kV 증가 시 1.63-2.95%로 완만하게 증가하나 양극측은 그 반대로 감소하는데 그 원인은 heel effect 현상 때문인가 사료된다. 후방산란율이 가장 크고, 그 다음이 전방산란율, 측방산란율 순으로 작아짐을 알 수 있다.

• Safety and Health at Work
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• 제6권4호
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• pp.289-294
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• 2015

Background: The type of payment is one of the important factors that has an effect on the health of employees, as a basic working condition. In the conventional research field of occupational safety and health, only the physical, chemical, biological, and ergonomic factors are treated as the main hazardous factors. Managerial factors and basic working conditions such as working hours and the type of payment are neglected. This paper aimed to investigate the association of the type of payment and the exposure to the various hazardous factors as an heuristic study. Methods: The third Korean Working Conditions Survey (KWCS) by the Occupational Safety and Health Research Institute in 2011 was used for this study. Among the total sample of 50,032 economically active persons, 34,788 employees were considered for analysis. This study examined the relation between the three types of payment such as basic fixed salary and wage, piece rate, and extra payment for bad and dangerous working conditions and exposure to hazardous factors like vibration, noise, temperature, chemical contact, and working at very high speeds. Multivariate regression analysis was used to measure the effect of the type of payment on working hours exposed to hazards. Results: The result showed that the proportion of employees with a basic fixed salary was 94.5%, the proportion with piece rates was 38.6%, and the proportion who received extra payment for hazardous working conditions was 11.7%. Conclusion: The piece rate was associated with exposure to working with tight deadlines and stressful jobs. This study had some limitations because KWCS was a cross-sectional survey.

• 한국방사선학회논문지
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• 제15권2호
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• pp.101-108
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• 2021

CT는 인체 내 장기의 해부학적 구조를 정확하게 나타낼 수 있으며, 영상의 분해능이 우수하다. Brain CT 검사 시 수정체의 방사선 감수성이 높아서 피폭의 영향을 많이 받는다. 본 연구는 수정체에 피폭선량을 감소하기 위해 비스무스와 텅스텐 필라멘트 차폐물질을 사용하여 Non-shield와 Shield에 대한 피폭선량의 변화와 차폐율을 비교 하고자 한다. 본 연구에서는 3D printing으로 제작한 비스무스, 텅스텐 필라멘트 차폐물질을 사용하여, 차폐물질 두께와 slice에 따라 피폭되는 선량을 측정하였다. 헤드팬텀을 고정시켜 안구에 Magicmax universal 선량계를 위치시켜 차폐 물질을 놓지 않았을 경우와 그 위에 차폐 물질을 놓았을 때 차폐율을 각각 비교하기 위해 두 물질을 1mm ~ 5mm 두께로 각각 측정하였다. 1 mm 두께의 필라멘트에서 비스무스 필라멘트는 26.8 %, 텅스텐 필라멘트는 43.1 % 차폐율이 나타났다. 따라서 비스무스 필라멘트보다 텅스텐 필라멘트에서 더 큰 차폐효과가 나타났다. 차폐체의 종류, 두께, 슬라이스 간격에 따라 선량을 측정한 결과, 비스무스 필라멘트 보다 텅스텐 필라멘트가 더 큰 차폐효과가 나타났다.