• Current Photovoltaic Research
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• 제4권4호
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• pp.155-158
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• 2016

Long-term stability of dye-sensitized solar cell (DSSC) module is critical for the commercialization. We investigated the effect of sealing technology on the long-term stability of the $10cm{\times}11cm$ sized DSSC modules. We applied the concept of secondary sealing to the module and then performed several stability tests such as humidity cycle, 1 sun light soaking and outdoor stability tests. The enhanced stability was confirmed for the DSSC module employing optimized sealing materials and architectures.

• Tribology and Lubricants
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• 제22권1호
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• pp.20-25
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• 2006

The stress behavior analysis of a-rings and packing for a LPG filling unit has been presented using a finite element analysis technique by non-linear MSC/MARC program. The sealing performance and endurance of a-rings and packing are affected by working conditions such as filling pressure, friction coefficient, compression ratio, and material properties. The elastomeric polymers of O-rings and packing are nitrile butadiene rubber (NBR) and polytetrafluoroethylene (PTFE), which are selected as proper materials of a-rings and packing based on the stress analysis results. The calculated FEM results showed that the proper material of O-ring is NBR as a secondary sealing component and the recommended material of packing is PTFE as a primary sealing unit during a LPG filling process.

• 반도체디스플레이기술학회지
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• 제12권2호
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• pp.45-50
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• 2013

This paper focuses on the fundamental issues for improving the efficiency and throughput of the AC PDP (Plasma Display Panel) manufacturing. The properties of the MgO protective layer affect the PDP efficiency. Especially, the secondary electron emission efficiency was affected on the deposition rate of MgO during the evaporation. In this study, the deposition rate of 5 $\AA$/s has given the maximum efficiency value of 0.05 It is demonstrated that the impurity gases such as $H_2O$, $CO_2$, CO or $N_2$, and $O_2$ can be remained inside the PDP panel before sealing and the amount of the impurity gases decreased rapidly as the base vacuum level increased, especially near $10^{-5}$ torr. The fundamental solution in order to overcome these problems is the vacuum in-line sealing process from the MgO evaporation to the final sealing of the panel without breaking the vacuum. We have demonstrated this fundamental process technology and shown the feasibility. The firing voltage was reduced down to 285 V at the base vacuum value of $10^{-6}$ torr, whreras it was about 328 V at the base vacuum value of $10^{-3}$ torr.

• 한국가스학회지
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• 제9권1호
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• pp.26-32
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• 2005

본 논문에서는 고압용기의 밀봉을 위해 사용하는 메탈시일의 설계 안전성에 대한 연구결과를 제시하고 있다. 기본적으로 고압용기의 1차적 밀봉은 메탈시일에 의해 이루어지고, 2차적 밀봉은 탄성체 고무로 제작된 0-링에 의해 가스누출이 차단된다. 유한요소해석 결과에 의하면, 가스누출 차단을 위해 사용한 알루미늄 소재의 밀봉장치는 강재를 사용한 경우보다 우수한 밀봉성을 보여주고 있다. 이것은 알루미늄 소재의 열팽창 특성이 상대적으로 우수하기 때문이다. 메탈시일과 압력용기 구조물에 걸리는 변형과 응력분포는 외부에서 공급된 가스압보다는 용기 내부에서 전달된 온도차에 의해 크게 지배를 받는 것으로 알려져 있다. 따라서 메탈시일의 소재는 통상적으로 $200^{\circ}C$이하로 유지되는 것이 소재의 강도와 밀봉성 측면에서 안전하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.10-12
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• 1998

Pumping liquid metal in nuclear power plant application by conventional centrifugal pumps pose difficulties such as bearing wear out at high temperatures and leak proof sealing of the liquid metal. MHD machine is obtained by replacing solid conducting secondary of conventional motors with ionized gas or liquid metal. It is used for reactor cooling pump because of construction simplicity, perfect sealing and easy operation/maintenance MHD pump is complicated because it includes electromagnetic and hydrodynamic phenomena. The principle of MHD Pumps is described in this paper. We design small laboratory size Flat Linear Induction Pump(FLIP) for transferring sodium.

• 한국추진공학회지
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• 제26권1호
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• pp.38-46
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• 2022

가스터빈 림 씰 연구의 주요 목표 중 하나는 고온의 주 유동 유입을 차단하여 디스크 내부의 열 손상을 방지하는 것이다. 이를 위해 지금까지 림 씰의 형상에 대한 연구와 함께 이를 개선하기 위한 연구도 수행되었다. 또한, 실제 터빈에 림 씰 형상을 적용하기 위해서는 터빈 작동 시에 발생할 수 있는 다양한 상황에 대한 연구가 필요하다. 따라서 본 연구에서는 수치해석을 통해 회전부 림 씰 위치의 두께가 변화하는 상황에 대해 연구하였다. 연구는 반지름 방향으로 로터 림 씰이 상향된 경우와 림 씰 내부 방향으로 로터 디스크가 확장된 상황을 모사하여 진행하였다. 그 결과, 유입되는 이차유동의 양에 따라 각 경우에서 서로 다른 내부 압력과 씰링 성능 및 유동이 발생함을 확인하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.158-162
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• 2000

Secondary flows in gas turbines, especially those associated tip clearance and labyrinth seals, have become a focus of interest for engine manufacturers. In the past, many analytical and experimental studies, which focused solely on the flows in either tip clearances or seals, have been conducted. This paper presents an analytical model that describes the flow response in a single stage turbine induced by a finite sealing gap at the turbine rotor. The flow is assumed to be axisymmetric and the analysis is done in the meridional plane. Upon going through the stage, the radially uniform upstream flow is assumed to split into two streams one associated with the seal and the other which has gone through the blades. The former is referred to as the leakage flow, and the latter is referred the as the passage flow. The passage flow is assumed to be inviscid and incompressible while the flow in the seal can be modeled as either inviscid or viscous. Thus, the model is capable of predicting the kinematic effects of labyrinth seals on the turbine flow field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1059-1061
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• 2005

The bushing currently applied to pole-mounted type loadbreak switch has porcelain bushing which is connected with the mold cone. This type has potential problems of uncertainty of sealing of the interface part and gas leakage on the connected part between bushing and switch tank due to the weight of the porcelain. The Composite Bushing can solve these problems and also the secondary problem of the potential accident owing to the fragment of the porcelain bushing in breakage due to the outer impact.

• 한국압력기기공학회 논문집
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• 제16권1호
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• pp.11-21
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• 2020

This study aims to develop and advance the evaluation technology for assessing PHWR safety. For this purpose, the complete loss of AC power or station blackout (SBO) was selected as a target accident scenario and the analysis model to evaluate the plant responses was envisioned into the MARS-KS input model. The model includes the main features of the primary heat transport system with a simplified model for the horizontal fuel channels, the secondary heat transport system including the shell side of steam generators, feedwater and main steam line, and moderator system. A steady state condition was achieved successfully by running the present model to check out the stable convergence of the key parameters. Subsequently, through the SBO transient analyses two cases with and without the coolant leakage via the PHTS pumps were simulated and the behaviors of the major parameters were compared. The sensitivity analysis on the amount of the coolant leakage by varying its flow area was also performed to investigate the effect on the system responses. It is expected that the results of the present study will contribute to upgrading the evaluation technology of the detailed thermal hydraulic analysis on the SBO transient of the operating PHWRs.

• 한국치위생학회지
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• 제16권1호
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• pp.45-52
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• 2016

Objectives: The purpose of the study was to investigate the cumulative dental caries rate of pit and fissure sealant in community public health program from 2005 to 2008 follow-up. Methods: The subjects were 4,768 students of 34 elementary schools in Gimcheon. The survey included direct oral examination and cumulative retention rate of pit and fissure sealant from 2005 to 2008. Data were analyzed using PASW statistical package version 18.0 and the level of significance was set at p<0.05. Results: The cumulative retention rate of sealant was 18%, 25%, and 33% after 1 year, 2 years, and 3 years, respectively. In addition, the cumulative retention rate of lower teeth was higher than that of upper teeth. Cumulative dental caries rate increased in sealed group and no sealed group. The cumulative dental caries rate decreased owing to tooth brushing frequency in sealed group and no sealed group. Conclusions: Regular and timely tooth brushing can maintain good oral health condition after tooth sealing. The school based oral health education can prevent loss of sealant and secondary caries.