• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1786-1795
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• 2015

It is common practice to identify the insulation faults of GIS through monitor the contents of SF₆ decomposed components. Partial discharges (PD) could lead to the decomposition of SF₆ dielectric, so new reactions usually occur in the mixture of the newly decomposed components including traces of H₂O and O₂. The new reactions also cause the decomposed components to differ due to the different amounts of H₂O and O₂ even under the same strength of PD. Thus, the accuracy of assessing the insulation faults is definitely influenced when using the concentration and corresponding change of decomposed components. In the present research, a needle-plate electrode was employed to simulate the PD event of a metal protrusion insulation fault for two main characteristic components SO₂F₂ and SOF₂, and to carry out influence analysis of trace H₂O and O₂ on the characteristic components. The research shows that trace H₂O has the capability of catching an F atom, which inhibits low-sulfide SF_x from recombining into high-sulfide SF₆. Thus, the amount of SOF₂ strongly correlates to the amount of trace H₂O, whereas the amount of SO₂F₂ is weakly related to trace H₂O. Furthermore, the dilution effect of trace O₂ on SOF₂ obviously exceeds that of SO₂F₂.

• 한국응용곤충학회지
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• 제13권4호
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• pp.235-243
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• 1974

산지별로 채취된 쌀, 보리, 밀에 함유된 잔류농약(유기수은제 및 유기감소제)을 Dithizone법과 GLC법으로 비교분석한 바 이에서 얻은 결과를 요약하면 다음과 같다. 1. Recovery는 유기수은에 있어서 TLC법$93\%$.에 비하여 GLC법$98\%$이 양호했고, 유기감소제는 GLC법으로 평균 약 $93\%$였다. 2. 시료중 유기수은의 잔류수준은 Dithizone법으로 쌀에 있어서 ND-0.053, .보리는 ND-0.051, 밀은 ND-0.033pm이었고, GLC법으로는 쌀은 trace(less than 0.002ppm)-0.036, 보리는 trace-0.030, 밀은 trace-0.025ppm으로 GLC법이 다소 낮은 수치였다. 3. 유기감소제의 잔류수준은 GLC법으로, 쌀에 있어서 BHC(trace-0.0090ppm), DDT(ND-0.0001ppm), Aldrin(trace-0.0032ppm), Heptachlor(race-0.0031ppm), Dieldrin(ND-0.0092ppm), Endrin(ND-0.0057ppm)이었는데, 수은화합물과 모두 공인최대허용량에 월등히 미달되는 안전수준이었다. 4. Column packing은 유기수은분리에는 $10\%$-DEGS/chromosorb-W,A,W., 유기감소제에는 $3\%$-DC-200/chromosorb-W,A.W.,가 적당하였는데, 유기수은제의 injection sample의 조제에 있어서 ?를 겸한 정제와 reduced glutatione에 의한 유출처리는 ghost peak의 소거와 성분 peak의 완전분리에 효과가 컸으며 검출감도도 높았다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.100-101
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• 2004

Many researches in Korea have been performed to understand the pollution of stream waters by acid mine drainage. However, few studies have been conducted regarding the effect of particulate and colloidal fractions on the transport of trace metals. To estimate harmful effects of trace metals, it is important to evaluate the particulate and colloidal metals as well as dissolved metals, because particulate and colloidal fractions of trace metals play an important role in transport of trace metals and may adversely affect habitats and organisms in riverine system. Colloids are solids with effective diameters in size range from 0.001 $\mu$m to 1 $\mu$m. According to Jone et al. (1974), metals in surface water, like Al, Fe, and Mn, require filtration with pore-size membranes smaller than 0.45 $\mu$m to define dissolved concentrations. The main objective of this study is to understand the effects of particulate, colloidal, and truly dissolved fractions on the transport and fate of trace metals in acid mine drainage. This study was conducted for the Onjeong creek in the Uljin mine area. Sampling was carried out in 13 sites, spatially covering the area from mine dumps to the downstream Onjeong reservoir. To examine the metal partitioning between particulate, colloidal, and truly dissolved fraction, we used successive filtration techniques consisting of conventional method (using 0.45 $\mu$m membranes) and tangential-flow ultrafiltration (using 0.001 $\mu$mm membranes). Ultrafiltration may seperate much smaller particles from aqueous phase (Josephson, 1984; Hernandez and Stallard, 1988). The analysis of metals were performed by inductively coupled plasma - atomic emission spectrometer (ICP-AES: model Perkin Elmer OPTIMA3000XL). Anions such as SO$_4$, Cl and NO$_3$ were measured with ion chromatograph (IC: model Dionex 120). Sample analysis is still in progress. The preliminary data show that the studied creek is severely polluted by Al, Fe, Mn, Pb and Zn. Toward upstream sites with relatively lower pH, less than 50% of Al and Fe occur in the sorbed form on particles or colloids, whereas more than 80% of Al and Fe occur in the sorbed form in downstream sites or tributaries with relatively higher pH. Less than 30% of Zn is present in particle or colloidal forms in the whole range of creek. Truly dissolved fraction of trace metals is negatively correlated with pH. The Kd values for Al, Fe and Zn consistently increase with increasing pH and decrease with increasing particle concentration.

• 대한화학회지
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• 제42권5호
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• pp.526-530
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• 1998

가스분석에서 극미량 성분분석은 반도체 관련 산업의 발달과 더불어 매우 중요하다. 특히 반도체 생산설비 중 가스공급시스템의 공기성분에 의한 오염은 제조자에게 어려움을 제공해 왔다. 그래서 공기성분의 분석은 반도체의 품질조절에 매우 중요하다. 본 연구에서는 가스분석에서 범용으로 사용되는 열전도도 검출기를 장착한 가스크로마토그래프와 액체질소트랩을 이용하여 헬륨과 수소 중의 질소와 아르곤성분을 분석하였다. 농축법으로 결정된 미지 시료의 농도를 다른 종류의 검출기와 비교 분석하였다. 이 방법에 의해서 결정된 농도는 결정된 확장불확도 범위 내에서 만족할 만한 결과를 보여 주었다.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1997년도 추계학술발표회 논문집
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• pp.260-265
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• 1997

가스분석에서의 극미량 성분분석은 반도체산업의 발달과 더불어 매우 중요하다. 이 실험에서는 가스분석에서 범용으로 사용되는 열전도도 검출기를 장착한 가스크로마토그라피와 액체질소트랩을 이용하여 헬륨과 수소중의 일산화탄소와 메탄성분을 분석하였다. 농축법으로 결정된 미지 시료의 농도를 다른 종류의 검출기와 비교분석하였다. 이 방법에 의해서 결정된 농도는 허용된 오차 범위에서 만족할 만한 결과를 보여 주었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.223-226
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• 2004

The importance of a proper sample preparation and analysis technique has getting attention due to the complicity of toxic elements of interest from environmental samples depend on analytical purposes. It is critical to use proper analytical method to evaluate trace elements concentration in many environmental samples especially for making remediation decisions. Therefore, it is critical to apply a proper sampling and analytical method such as EPA publication SW-846 (Test Methods for Evaluating Solid Waste, Physical/chemical Methods). The objective of this study was to compare the USEPA Methods 3050B, modified 3050B, 305 la, and KBSI method (modified EPA 3052 Method) in term of recovery rate of metals. The NIST SRM (Montana soil) was used to compare the extraction and digestion efficiency. After sample has been collected the analysis were achieved by ICP-MS (Elan 6100, Perkin Elmer) as well as ICP-AES (Ultima 2C, JY) for trace elements and major elements.

• 정보처리학회논문지C
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• 제18C권4호
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• pp.213-216
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• 2011

차분전력공격(Differential Power Analysis, DPA)의 효율성은 수집신호 정렬도를 비롯한 다양한 잡음에 많은 영향을 받는다. 최근에 Ryoo등은 잡음 신호를 극복하여 DPA의 분석성능 향상을 가져오는 효과적인 신호처리기법을 소개했다. 본 논문에서는 기존에 제안된 신호처리기법이 적용되지 않은 경우를 보이고, 이에 대한 해결방안으로 차분파형모델(Differential Trace Model, DTM)을 제안한다. 또한 제안된 DTM이 DPA 분석에 적합한가에 대해 이론적으로 증명하고 실험을 통해 검증한다.

• 대한건축학회연합논문집
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• 제21권5호
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• pp.109-116
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• 2019

The Seoul city recommended that old apartments be preserved, and as part of that, it decided to preserve some of the buildings for Jamsil Jugong, which was built in 1977, and Gaepo Jugong, which was constructed in 1981. The purpose of this study was to compare and review newspaper articles with two perspectives positive and negative about how the social perception of 'apartment trace remaining' was being constructed. By looking at the meaning of keywords delivered by newspaper articles and the interaction structure between keywords through the analysis of semantic networks, we analyzed how the media is pursuing an issue on the topic of preservation of architectural cultural heritage. The analysis results confirmed that there was a clear difference between positive and negative newspaper. Positive articles dealt with utilization from the point of view of keywords linked to preservation, and negative articles showed that keywords related to the property and backlash of residents linked to the policy of the Seoul Metropolitan Government were linked, leading to high negative public opinion.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1448-1459
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• 2023

A key element of the safety analysis is Loss of Coolant Analysis (LOCA) which must be performed using system thermal-hydraulic codes. These codes are extensively validated against separate effect and integral experiments. RELAP/SCDAPSIM is one such code that may be used to predict LBLOCA response in a CANDU reactor. The RD-14M experiment selected for the Best Estimate Plus Uncertainty study is a 44 mm (22.7%) inlet header break test with no Emergency Coolant Injection. This work has two objectives first is to simulate pipe break with RELAP and compare these results to those available from experiment and from comparable TRACE calculations. The second objective is to quantify uncertainty in the fuel element sheath (FES) temperature arising from model coefficient as well as input parameter uncertainties using Integrated Uncertainty Analysis package. RELAP calculated results are found to be in good agreement with those of TRACE and with those of experiments. The base case maximum FES temperature is 335.5 ℃ while that of 95% confidence 95^th percentile is 407.41 ℃ for the first order Wilk's formula. The experimental measurements fall within the predicted band and the trends and sensitivities are similar to those reported for the TRACE code.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.2974-2989
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• 2024

The one-dimensional Two-Fluid concept uses an area-average approach to simplify the time and phase-averaged Two-Fluid conservation equations, making it more suitable for addressing difficulties at an industrial scale. Nevertheless, the mathematical framework has inherent weaknesses due to the loss of details throughout the averaging procedures. This limitation makes the conventional model inappropriate for some flow regimes, where short-wavelength perturbations experience uncontrolled amplification, leading to solutions that need to be physically accurate. The critical factor in resolving this problem is the integration of closure relations. These relationships play a crucial function in reintroducing essential physical characteristics, thus correcting the loss that occurs during averaging and guaranteeing the stability of the model. To improve the accuracy of predictions, it is essential to assess the stability and grid dependence of one-dimensional formulations, which are particularly affected by closure relations and numerical schemes. The current research presented in the text focuses on improving the well-posedness of the TFM, specifically within the TRACE code, which is widely utilized for nuclear reactor safety assessments. Incorporating a bubble collision model in the momentum equations is demonstrated to enhance the TFM's resilience, especially in scenarios with high void fractions where conventional TFMs may face challenges. The analysis presents a linear stability analysis performed for the transient one-dimensional Two-Fluid Model of system code TRACE within the framework of vertically dispersed flows. The main emphasis is on evaluating the stability characteristics of the model while also acknowledging its susceptibility to closure relations and numerical techniques.