• 한국산업보건학회지
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• 제18권2호
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• pp.133-140
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• 2008

In order to evaluate the possible environmental lead hazard in children's playground and to test the practicability of field portable x-ray fluorescence(FPXRF) for environmental lead measurement, authors investigated lead concentration of lead-based paint on the surface of children's playing equipments in the playground of 13 apartments using FPXRF at the site in city A, Choongnam province. 93 spots were determined surface lead concentrations 3 times each using a FPXRF. Out of 93 spots, 83 spots (92%) were revealed to have lead in paint and mean concentration was $1.12{\pm}1.76mg/cm^2$. The mean concentration of lead on the surface of playing equipments at the apartments near the main street was $1.20mg/cm^2$ and higher than those at the apartments far away from the main street($0.81mg/cm^2$)(p<0.05). The mean concentration of lead on the surface of playing equipments painted with yellow color was $3.23mg/cm^2$ and the highest among all colors, whereas equipment painted white color was non-detectable. PVC and etc materials for construction of playing equipment showed higher surface lead concentration than other materials. The result suggests that it is necessary to be taken caution of the lead exposure in the playground of apartment and it should be taken any kind of confirmative action to prevent unwanted lead exposure from surface lead source of playing equipment. Authors found that FPXRF was very reliable and useful for field measurement to detect lead on the painted surface.

• 한국자기학회지
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• 제11권2호
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• pp.50-57
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• 2001

강자성 극박소재에 유기된 잔류응력을 검출하기 위하여 자기유도형 탐촉자(probe)를 설계·제작하였으며, 이를 장착한 잔류음력 평가시스템은 박판내에 유기된 잔류응력의 주응력 방향과 크기를 효과적으로 결정하여 준다. 이 시스템을 반도체 칩 팩키지(package)용으로 사용하는 Fe-42Ni계 lead frame 판재의 잔류응력 검출에 적용한 결과, 양호재 및 잔류응력과다 불량재에 대한 출력전압은 명확히 구별되었고, 잔류응력이 축적된 판재는 양호재와 비교하여 응력의 분포 및 크기에 있어 항상 차이를 나타내었다. 이러한 차이는 탐촉자에 투입하는 전류와 주파수의 함수로 잘 분해되어질 수 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1081-1090
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• 2024

The liquid Lead-bismuth eutectic is used as the coolant for Gen-IV reactor concepts. However, due to its strong corrosive and high operating temperature, it is difficult to accurately measure the flow rate in long-term operating conditions. Venturi flowmeter is a simple structured flowmeter, which plays a very important role in the flow measurement of high-temperature liquid metals, especially since the existing flowmeters are difficult to be competent. It has the advantages of easy maintenance and stable operation. Therefore, it is necessary to study the operating conditions of the venturi flowmeter under high-temperature conditions. This work performs a series of simulations of the fluid-solid interaction between the flow liquid metal and venturi flowmeter with COMSOL software, including the dimensional sensitivity analysis of the venturi flowmeter to explore the most suitable structure and parameters for liquid heavy metal, the sensitivity analysis of the geometric parameters of the venturi tube on the varying conditions. It shows that when the contraction angle of the venturi flowmeter is 33°, the diffusion angle is 13°, the diameter of the throat is 8 mm, and the temperature of the lead-bismuth eutectic is 733.15 K, it is most suitable for the measurement in the lead-bismuth circuit.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.358-359
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• 2012

본 연구에서는 범용적인 건강 모니터링에 활용할 수 있는 생체신호인 심전도를 일반 가정 내에서 뿐만 아니라 일상생활 중에서도 실시간으로 편리하게 측정할 수 있도록 초소형 저전력의 착용형 심전도 계측시스템을 구현하였다. 이를 위하여 표준 12-lead법이 아닌 모바일 또는 휴대용 장치에 적합한 2-lead법을 사용하여 심전도 계측부를 구현하였고, 심전도 계측부를 베이스 노드로 하여 심전도 신호를 가정 내 또는 실외에서도 무선으로 전송 할 수 있도록 구현하였다. 먼저 가정 내에서는 저 전력 무선센서노드를 이용하여 심전도 신호를 실시간으로 PC에 전송하여 모니터링이 가능하도록 구현 하였고, 실외에서는 저전력 통신 방식인 Bluetooth 2.0을 사용하여 스마트폰으로 심전도 신호를 실시간으로 전송해 모니터링 할 수 있도록 구현하였다.

• 한국산업보건학회지
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• 제23권2호
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• pp.164-168
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• 2013

Objectives: This study was aimed at the examination of the lead exposure status of smelting process workers in steelmaking using scrap iron. Methods: The study was conducted from July to September 2012 by means of measurements taken during the smelting process, with 45 minutes set for a one-time smelting work cycle when it comes to personal air sample and area air sample. As such, daily work hours were classified into 360 minutes for measurement. The analysis of lead concentration was conducted using AAs based on the NIOSH 7300 method. Results: In the case of the personal specimens that were subjected to periodical measurement 45 minutes per one session during the smelting process, 40 out of 42 specimens measured were found to contain lead, with an average concentration level of $0.028mg/m^3$ (Max: $0.182mg/m^3$, Min: $0.005mg/m^3$, TWA-more than 50%: 4 out of 6 units). In the case of regional specimens, lead was detected in 45 out of 48 specimens measured, with an average concentration level of $0.037mg/m^3$ (Max: $0.220mg/m^3$, Min: $0.007mg/m^3$ ). In the case of regional specimens subjected to measurement using a day as the work cycle, lead was detected in 15 out of 15 specimens measured, with an average concentration level of $0.049mg/m^3$ (Max: $0.478mg/m^3$, Min: $0.005mg/m^3$ ). Conclusions: It concluded that smelting process workers in steelmaking are exposed to lead because scrap iron is used as a raw material. It is thus necessary to introduce legal management to prevent occupation-related disease in smelting process workers in steelmaking.

• 한국방사선학회논문지
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• 제4권4호
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• pp.29-32
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• 2010

본 연구는 교토대학 원자로실험소의 46-MeV전자선형가속기에서 발생된 전자선을 Ta표적에 충돌시켜 발생된 중성자를 이용하였다. 발생된 중성자는 납감속측정장치(LSDS:Lead Slowing-down Spectrometer))속에서 감속되었고 중성자비행시간법(TOF:Time-of-Flight)을 이용하여서 중성자에너지를 선별하여 $^{197}Au$의 중성자포획단면적을 중성자에너지 0.1 eV에서 10 keV범위에 걸쳐 측정하였다. 발생된 중성자속을 측정하기 위하여 $BF_3$검출기속의 $^{10}B(n,{\gamma})$반응을 이용하였고 이것을 이용하여 중성자 반응 단면적을 상대적으로 얻었다. TOF방법으로 얻어진 결과는 1 eV에서의 결과(24.5 b)에 규격화되었다. 기존의 실험결과들과 평가결과들인 JENDL/D-99 Dosimetry File과 비교하였다.

• 한국경영과학회지
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• 제34권4호
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• pp.91-112
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• 2009

The bullwhip effect means the phenomenon of increasing demand variation as moving UP to the upstream in the supply chain. Therefore, it is recognized that the bullwhip effect is problematic for effective supply chain operations. In this paper, we exactly quantifies the bullwhip effect for the case of stochastic lead time and seasonal demand in two-echelon supply chain where retailer employs a base-stock policy considering SARMA demand processes and stochastic lead time. We also investigate the behavior of the proposed measurement for the bullwhip effect with autoregressive and moving average coefficient, stochastic lead time, and seasonal factor.

• 소성∙가공
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• 제10권5호
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• pp.425-432
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• 2001

In order to investigate the influences of process parameters on the shape of lead frame, experimental study has been carried out. In the experiment, dimensional accuracy of the die sets, measurement accuracy has been managed carefully enough to simulate actual lead frame blanking process. With the blanking of square-shaped specimen, the effects of clearance, strip holding pressure and bridge width on the shape of blanked profile have been investigated. Experimental results show that the burnish ratio is increased as the clearance decreases. the strip holding pressure increases, and bridge width increases. Although the results seems to be similar to the ordinary blanking, the lead frame blanking shows a subtle different characteristics to the ordinary blanking due to the narrow bridge width.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.332.2-332
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• 1999

• Safety and Health at Work
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• 제13권4호
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• pp.493-499
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• 2022

Background: The purpose of this study is to construct a job-exposure matrix for lead that accounts for industry and work processes within industries using a nationwide exposure database. Methods: We used the work environment measurement data (WEMD) of lead monitored nationwide from 2015 to 2016. Industrial hygienists standardized the work process codes in the database to 37 standard process and extracted key index words for each process. A total of 37 standardized process codes were allocated to each measurement based on an automated key word search based on the degree of agreement between the measurement information and the standard process index. Summary statistics, including the arithmetic mean, geometric mean, and 95th percentile level (X95), was calculated according to industry, process, and industry process. Using statistical parameters of contrast and precision, we compared the similarity of exposure groups by industry, process, and industry process. Results: The exposure intensity of lead was estimated for 583 exposure groups combined with 128 industry and 35 process. The X95 value of the "casting" process of the "manufacture of basic precious and non-ferrous metals" industry was 53.29 ㎍/m³, exceeding the occupational exposure limit of 50 ㎍/m³. Regardless of the limitation of the minimum number of samples in the exposure group, higher contrast was observed when the exposure groups were by industry process than by industry or process. Conclusion: We evaluated the exposure intensities of lead by combination of industry and process. The results will be helpful in determining more accurate information regarding exposure in lead-related epidemiological studies.