• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.402-408
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• 2016

Background: Ascertainment bias are common in epidemiologic studies to assess the association between thyroid cancer risk and living near nuclear power plants because many thyroid cancers are diagnosed by chance through health examination. We surveyed the ultra sonography (USG) examination history and conducted thyroid and breast USG in residents living near nuclear power plants. Materials and Methods: The study population comprised 2,421 residents living near nuclear power plants in Korea. Information on demographic characteristics, including diagnostic examination history, was collected by interview using questionnaires. USG examination was conducted to evaluate the presence of thyroid nodules and breast lesion. Study participants were divided into 3 groups according to the distance of their respective villages from a nuclear power plant. The proportions of USG examination history and prevalence of thyroid nodules and breast lesions were compared between groups. Results and Discussion: Examination histories of thyroid USG were 23.1%, 13.7%, and 10.5% in men and 31.3%, 26.7%, 18.3% in women in the short, intermediate, and long distance groups, respectively. There were significant inverse associations between thyroid USG history and the distance from nuclear power plants (P for trend = 0.001 for men and 0.017 for women). However, there was no association between the distance of villages from nuclear power plants and prevalence of thyroid nodules. Conclusion: Our results suggest that there may be an ascertainment bias in population-based studies examining the harmful effects of NPPs examination and researchers should pay attention to ascertainment bias resulted from differential health examination. Correction for ascertainment bias, active follow-up and examination for all study population to remove differential health examination is needed.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.793-794
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• 2004

• 전기의세계
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• 제14권3호
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• pp.10-17
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• 1965

This paper presents a method of the voltage-reactive power control in the long and short range operations and introduces a conception, "optimum control pattern." The optimum control pattern, aiming at the over-all system control, is defined as the optimum voltage distribution which minimizes the system operating cost under the conditions that the specified power be supplied and the system voltage be kept within the specified bounds. The following procedure was adopted to obtain this optimum pattern. In the first place, a power system was divided into three blocks, namely, load, substation and generator. Lagrange's, multiplier method is applied to each block in turn, paying attention only at the operating voltage distribution. Phase angles at each bus are then modified so that the continuity of active power is maintained. This procedure may be called "block relaxation method with Lagrange's multipliers." In a long range operation, this control pattern determines the optimum installation capacity of reactive power sources. In a short range operation, it also gives the reference state of real time control and the optimum switching capacity of reactive power souces. The real time control problem is also studied from the standpoint of cooperation of control devices such as generators, shunt capacitors, shunt reactors and ratio load controllers. A proposal for the real time control will contribute to the automation of power system operation in the near future. in the near future.

• Journal of Welding and Joining
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• 제23권1호
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• pp.61-68
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• 2005

An analytical method for determining the thermal stress distributions in a 3-layered beam is developed, which is focused on the end effects. This method gives the stress distributions which satisfy the stress-free boundary condition at the end completely. For verification of the method, a numerical example which was introduced by other researchers is treated. The stress distributions agree with the results of other researchers. The results show that the show and peeling stresses at the interfaces are significant near the edge and become negligible in the interior region.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.277-280
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• 2006

This paper deals with the possibility on the hybrid power system concerning wind energy at a really existing island, Sunyoo-do in the west sea near Seamangeum. In the present stage, Diesel system produces all the electrical power of the Island. However, in the new proposed system of Diesel and wind energy, an optimized guideline for drive from the economic analysis on this hybrid system is given by a mathematical and statistical modelling with a share software HOMER (hybrid optimization model for electric renewables). After a series of analysis it has been shown that the hybrid system can reduce the total expenses as well as air pollution.

• 전자공학회논문지D
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• 제34D권11호
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• pp.20-24
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• 1997

We have successfully fabricated high power (~20W) laser diode array, which are useful for pumping Nd:YAG lasers. The laser diode aray has 20 100.mu.m-wide cahnnels of which space was adjusted to 350.mu.m to improve thermal characteristics. And channel width is 100.mu.m. For an uncoated LD array, the output power of 15.66W has been obtained at 41A under quasi-CW operation, which results in about 0.42W/A slope efficiency. After aR(5%) and HR (95%) coatings on both facets, the output power was improved up to 21.18W at 40A under the same operation as above and the slope efficiency was 0.795W/A. On the other hand, by using a near field measurement system consisting of objective lens, eyepiece, CCD camera and image processing board, the typical near field patten of 1*20 LD array was observed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1131-1136
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• 2008

The single-phase PWM converter employing power semiconductors is currently applied to the power unit of high-speed rail vehicle and increasingly used as the front-end converter with properties of near unity power factor. Power factor and harmonics are increasingly important needs for drive system of high-speed rail vehicle. The proposed approach has many advantages which include fewer semiconductor components, simplified control, high performance features and satisfies IEC 555 harmonic current standards. Simulation results show that the dc-link voltage control obey the reference value during constant load and input current is near sinusoidal.

• 한국전자파학회논문지
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• 제25권2호
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• pp.149-155
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• 2014

본 논문에서는 모바일폰에 적용되는 종래의 코일형 무선 전력 전송(WPT) 루프 안테나 및 FPCB형 근거리 통신(NFC) 안테나에 비해 두께를 1/2로 줄이면서도 동등 이상의 안테나 성능을 구현한 전자기 유도 방식의 FPCB형 WPT 및 NFC 일체형 루프 안테나를 제안하였다. 루프 안테나의 패턴 두께, 전자파 흡수체 및 금속 성분의 배터리 영향도 분석, 전자파 흡수체의 두께에 의한 안테나 성능 비교를 통해 루프 안테나의 설계 인자의 범위를 설정하였다. 본 논문에서 제안한 안테나는 3 oz 단면 FPCB에 전자파 흡수체를 부착하여 총 두께 0.45 mm로 시제품을 제작하였으며, NFC 안테나 성능은 국내 이동통신사 규격 및 EMVCo. 규격을 만족하며, WPT 안테나 성능은 종래의 코일형과 동등 이상인 68.1 %의 무선 전력 전송 효율을 얻었다. 이러한 결과들로써 본 연구에서 제안한 일체형 안테나는 모바일폰 WPT 및 NFC 안테나로서 이용될 수 있음을 확인하였다.

• 소성∙가공
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• 제18권8호
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• pp.589-595
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• 2009

The hot forming process of an exhaust CAM for vessel engine was designed by finite element(FE) simulation and experimental analysis. An aim of process design was to achieve the near-net shaped CAM forgings by hot forging process. Based on the compression test results of the low alloy steel, power dissipation map was generated using the the dynamic materials model(DMM). From the map, the initial heating temperature was determined as 1200oC. FE analysis was simulated to predict the formation of forging defects and deformed shape with different forging designs. Optimum process design suggested in this work was made by comparing with the CAM for vessel engine manufactured by actual forging process.

• 터널과지하공간
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• 제4권3호
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• pp.287-296
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• 1994

Safety-related structures of power plants have to be protected against the effects of possible hazards and natural phenomena. Earthquakes are considered a major dynamic design loading as a requirement of plant design, but the effects of blast-induced vibratons are not. Due to the difficulties of obtaining construction site for new plants, following ones are inevitably being built in the site adjacent to existing power plants. Therefore considerable thought has been recently given to the dynamic loading generated by blasting works near the plants. In this paper, discussed is applicability of existing vibration standards and industrial codes to the blasting works near safety related structures. Also evaluated are the parameters for the safe vibration limits such as measure of vibration level, frequency consideration, structure response, propagation equation, etc.