• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.239-242
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• 2009

고휘도 방전(High Intensity Discharge ; HID)램프는 고압기체 또는 증기 중의 방전에 의한 발광을 이용한 램프로서 고압수은램프, 메탈핼라이드램프 및 고압나트륨램프를 총칭한다. 이들 HID램프는 작은 발광관에서 고출력의 광속을 발산시킬 수 있기 때문에 주로 많은 광속을 필요로 하는 장소에 폭넓게 사용되어지고 있다. 특히, 메탈핼라이드램프의 경우 금속 고유의 여기파장을 이용하여 기존 수은방전에서 결핍된 스펙트럼을 보충할 수 있기 때문에 보다 높은 발광효율과 연색성을 향상시킬 수 있어 HID램프 중 가장 이상적인 광원으로 평가받고 있다. 근래에는 기존 발광관 재료로 사용해 오던 석영(Quartz)을 내열성 및 내식성 등이 우수한 alumina ceramic으로 교체한 세라믹 메탈핼라이드(Ceramic Metal Halide ; CMH) 램프가 개발되어 램프의 소형화를 통해 옥내 상업용 조명시설에 급속히 보급이 이루어지고 있다. 본 논문에서는 이러한 CMH램프의 우수한 특성을 살펴보기 위하여 국외 선진제품에 대한 전기적, 광학적 특성을 살펴보았다.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.562-569
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• 1994

In this study improvement of transient analysis model, KOTRAC, for the passive reactor has been performed. In the KOTRAC, mixture drift flux model is adopted to simulate thermal hydraulic behavior, which can simulate ECCS injection in the passive plant. However, there is a difficulty to handle complete phase separation phenomena due to the near-zero density, which may occur in the pressurizer surge line or horizontal flow paths. In this study, a couple of model changes to over-come Courant limit feilure has been examined. One of key features is to substitute flow distribution parameters with Ishii's correlation. Corrected results are nil compared to those of RELAP/MOD3 analysis.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.351-357
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• 2004

We have investigated the intensity of Cu 510.6 nm emission line in see-through hollow cathode glow discharge (st-HCGD) for the development of medical Cu vapor laser. In order to acquire the stable plasma in st-HCGD cell at high current, several factors such as current, the length and the inner diameter of cathode tube, the shape of the tube, and the range of the sputtering range were tested. An optimum condition in our st-HCGD cell was obtained at 600 V, 700 mA, 2.3 Torr of Ar gas (100 SCCM), and 40 mm of tube with 4-11-4 mm type cathode design. Also, it was indirectly observed that temperature in the cell could reach more than $1,000{\circ}C$ since Cu cathode was melt at the current more than 700 mA (melting point of Cu, $1084{\circ}C$).

• 월간산업보건
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• s.328
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• pp.55-59
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• 2015

톨루엔-2,4-디이소시아네이트, 톨루엔-2,6-디이소시아네이트 각각 또는 두 이성체 혼합물(TDI)에 대하여 TLV-TWA는 0.005 ppm, TLV-STEL은 0.02 ppm으로 직업적 노출기준을 권고하고 있다. 본 수치는 호흡기에 대한 영향과 과민성 반응에 대한 높은 발생 가능성을 최소화하기 위한 것이다. 산업현장에서 증기상 TDI 물질은 점막, 호흡기계에 심한 자극을 일으켜 천식과 같은 증후군 등 급성 발작을 유발한다. 고농도에 노출시 심한 기관지 경련, 폐렴, 폐부종, 두통, 불면증과 기관지염으로 이어질 수 있다. TDI에 상당 부분 노출되면 대부분의 사람들은 위와 같은 건강 영향을 경험하게 된다. 심지어 처음 노출되었을 경우에도 발생된다. TDI 노출 관련 연구자들은 일반 근로자들이 0.02 ppm 수준 정도로 가끔 노출되는 경우 건강 영향을 받지 않으나, 0.02 ppm이 무영향 수준으로 간주될 수 있는 그 어떠한 증거도 없다고 결론을 내렸다. TDI에 일단 감작되면 몇몇 근로자들은 노출 중단 후에도 몇 년 동안 건강 영향 증세가 지속된다. 따라서 감작제 표기는 호흡 노출을 통한 알레르기성 감작 증세의 명확한 증거로서 권고된다. A4(비발암성 물질) 표기는 생쥐와 흰쥐들을 대상으로 수행된 위장관 투여 연구와 흡입 연구들을 통해 얻어진 동물 노출 데이터에 근거하여 설정되었다. 불충분한 데이터로 피부 표기는 권고되지 않았다.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.2
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• pp.407-414
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• 1995

원자력발전소의 주요 기기들에 대한 가동중검사는 관련법규에 따라 철저히 수행되고 있다. 그러나 최근 선진국에서는 이에 만족하지 않고 원전 기기의 안전성을 더욱 확고히 하기 위해 기존의 가동중검사 요건을 계속 강화하고 있으며, 원전 관련 당사자들은 강화된 요건들을 충족시키기 위한 노력을 끊임없이 계속하고 있다. 이 글에서는 원전 기기 가동중검사 신규 요건들인 초음파탐상검사 시스템의 기량검증(Performance Demonstration) 요건, 비파괴검사자 및 초음파검사자 자격 인정 요건(ANSI/ASNT CP-189, Appendix VII of ASME Sec. XI), 증기발생기 전열관 와전류검사, 신호평가자 자격인정(Qualified Data Analyst : QDA), 미국규제기관(NRC)에서 발행하고 있는 NRC Bulletin, NRC information 등의 가동중검사 관련 사항들을 살펴보고 선진 외국에서는 이들 요건 및 정보에 대해 어떻게 대처하고 있는가를 알아본다. 또한 국내에서도 이들 신규 요건에 대한 대처 현황과 대처 방안을 모색한다.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1367-1370
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• 1997

This paper presents a vision algorithm for finding the centers of steam generator tubes using the generalized symmetry transform, which is used for ECT(Eddy Current Test) of steam generator tubes in nuclear power plants. The geometrical properties of the image representing steam generator tubes shows that they have amost circular or somewhat elliptic appearances and each tube has strong symmetry about its center. So we apply the generalized symmetry transform to finding centers of steam geneator tubes. But applying the generalized symmetry transform itself without any modification gives difficulties in obtaining the exact centers of steam generator tubes. But applying the generalized symmetry transform itself without any modification gives difficulties in obtaining the exact centers of tubes due to the shadow effect generated by the local light installed inside steam generator. Therefore we make the generalized symmetry transform modified, which uses a modified phase weight function in getting the symmetry magnitude in order to overcome the misleading effect by the local light. The experimental results indicate that the proposed vision algorithm efficiently recongnizes centers of steam generator tubes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.102-105
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• 2001

The spring back taking place after the coiling process of steam generator tube leads to the dimensional inaccuracy. In order to reduce the spring back, tension force was applied to the one end of the tube during forming. In this work, parametric study using FEM was performed to find the appropriate magnitude of tension force. The force that induces minimum suing back was found by simultaneously taking account of suing back amount, cross-sectional ovality, and thickness of the tube wall after deformation. In addition, stress relieving by heat treatment was also simulated as an alternative to the former method. The latter was found to be more effective under the given constraints.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.83-85
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• 1996

Major cause of defects in steam generator tubes at nuclear power plant is the accumulation of magnetite and other byproducts of corrosion in the crevice gap between support plates and tubes. Since damaged tubes result in contamination of the secondary coolant by the radioactive primary coolant, they represent a safety hazard. Early detection of magnetite buildup is, therefore, imperative in order to take remedial measures such as chemical flushing. Although the eddy current testing is being used for the inspection of steam generator tubes, the interpretation of resulting signals is generally a difficult task. This paper uses the phase of sensor coil emf as the test signal to find a way of easier signal interpretation. Numerical study using FEM shows that the shape of resulting signal is good for identifying the relative position of the probe to the support plate, and for discreminating the different shapes and degrees of magnetite buildup in the crevice gap region.

• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.1
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• pp.40-45
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• 1993

The steam generator tubes of the nuclear power plant should be inspected using eddy current techniques. Recently the crack-like defects become a major concern for the integrity of the steam generator tubes. These defects could be detected by the MRPC(Motorized Rotating Pancake Coil) method, not by the conventional bobbin coil method. In this paper it has been attempted to estimate the length of the cracks at the tube expansion region using of MRPC technique. The lengths of both axial and circumferential cracks show a tendency of overestimation compared to the real lengths. As the depths of the defects decrease from 100% through 50% of the wall thickness, the error of the length estimation is increased.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.11-15
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• 2004

The fretting-fatigue by leaking is one of the significant degradation in steam generator tubes. In this study, the burst pressure of inclined damaged steam generator tubes were obtained from three criterions by using the finite element method. The analysis results were also compared with the experiment data from published references and they showed a good agreement with the experiment data.