• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.153-164
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• 2019

The presence of thermal bridges in a building envelope cause additional heat loss which increases the heating energy. Given that a higher building insulation performance is required in these cases, the heat loss via thermal bridges is a high proportion of the total heat energy consumption of a building. For the dry exterior insulation system that uses mullions and transoms to fix insulation and exterior materials such as stone and metal sheet, the occurrence of thermal bridges at mullions and transoms is one of the main reasons for heat loss. In this study, a dry exterior insulation system using the truss insulation frame (TIF) was proposed as an alternative to metal mullions. To evaluate the building envelope performance, structural, air-leakage, water-leakage, fire-resistance, thermal, and condensation risk tests were conducted. In addition, the annual energy consumption associated with heating and cooling was calculated, including the linear thermal transmittance of the thermal bridges. As a result, the dry exterior insulation system using TIF achieved the allowable value for all tests. It was also determined that the annual heating load of a building was reduced by 36.7 % when the TIF dry exterior insulation system was used, relative to the dry exterior insulation system using steel pipes without additional insulations.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.2
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• pp.94-101
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• 2015

To mitigate the greenhouse gas emission, many carbon capture and storage projects are underway all over the world. In Korea, many studies focus on the storage of $CO_2$ in the offshore sediment. Assurance of safety is one of the most important issues in the geological storage of $CO_2$. Especially, the assessment of possibility of leakage and amount of leaked $CO_2$ is very crucial to analyze the safety of marine geological storage of $CO_2$. In this study, the leakage of injected $CO_2$ through fault was numerically studied. TOUGH2-MP ECO2N was used to simulate the subsurface behavior of injected $CO_2$. The storage site was 150 m thick saline aquifer located 825 m under the continental shelf. It was assumed that $CO_2$ leak was happened through the fault located 1,000 m away from the injection well. The injected $CO_2$ could migrate through the aquifer by both pressure difference driven by injection and buoyancy force. The enough pressure differences made it possible the $CO_2$ to migrate to the bottom of the fault. The $CO_2$ could be leaked to seabed through the fault due to the buoyancy force. Prior to leakage of the injected $CO_2$, the formation water leaked to seabed. When $CO_2$ reached the seabed, leakage of formation water stopped but the same amount of sea water starts to flow into the underground as the amount of leaked $CO_2$. To analyze the effect of injection rate on the leakage behavior, the injection rate of $CO_2$ was varied as 0.5, 0.75, and $1MtCO_2/year$. The starting times of leakage at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 11.3, 15.6 and 23.2 years after the injection, respectively. The leakage of $CO_2$ to the seabed continued for a period time after the end of $CO_2$ injection. The ratios of total leaked $CO_2$ to total injected $CO_2$ at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 19.5%, 11.5% and 2.8%, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.255-258
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• 2009

Leading developed countries have studied energy self-sufficient houses such as zero or low energy buildings to reduce energy consumption for buildings since the early 1990s. Moreover, some developed countries have actually constructed self-sufficient houses and operated them for demonstration, expanding use of such houses. Korea has also established Zero Energy Solar House(ZeSH) and studied energy independence. Therefore, this study analyzed research result regarding ZeSH, self-sufficient energy house hold of Korea, found out technologies used for heating energy independence, used building interpretation program(ESP_r) to evaluate performance of each factors and analyzed energy reduction quantitatively. Results from the research are as follows: Reduction rate of actual detached house's heating load was also analyzed quantitatively depending on application of each technology. When each factor was applied step-by-step, annual reduction rate of heating load depending on increase in insulation thickness reached 6.6~22.2 %. Annual reduction rate of heating load depending on increase insulation thickness, and change in window heating performance and area ratio reached 31.5 %. Annual reduction rate of heating load through high-sealing and high-insulation depending on change in leakage rate reached 40.0~88.9 %. Annual reduction of heating load, when Mass Wall and attached sun space was applied were applied reached 28.5~39.2 %, respectively.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.62-71
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• 2017

This paper presents a low-power voltage converter based on a reconfigurable capacitor array. Its energy recycling capacitor array stores the energy during a charge stage and supplies the voltage during an energy recycle stage even after the power source is disconnected. The converter reconfigures the capacitor array step-wise to boost the lost voltage level during the energy recycle stage. Its energy saving is particularly effective when most of the energy remaining in the charge capacitors is wasted by the leakage current during a longer sleep period. Simulations have been conducted using a voltage source of 500 mV to supply a $V_{DD}$ of around 800 mV to a load circuit consisting of four 32-bit adders in a 65-nm CMOS process. Results demonstrate energy recycling efficiency of 85.86% and overall energy saving of 40.14% compared to a conventional converter, when the load circuit is shortly active followed by a long sleep period.

• Corrosion Science and Technology
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• v.8 no.5
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• pp.188-192
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• 2009

A forced outage due to a steam generator tube leak in a Korean nuclear power plant was reported.1) Primary water stress corrosion cracking has occurred in many tubes in the plant, and they were repaired using sleeves or plugs. In order to develop proper repair criteria, it is necessary to understand the leak behavior of the tubes containing stress corrosion cracks. Stress corrosion cracks were developed in 0.1 M sodium tetrathionate solution at room temperature. Steam generator(SG) tubes with short cracks were successfully fabricated with a restricted solution contact method. The leak rates of the degraded tubes were measured at room temperature. Some tubes with 100 % through wall cracks showed an increase of leak rate with time at a constant pressure.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.145-145
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• 2015

처음 유기물의 인광 발견 이후 Host-dopant 시스템을 이용하여 Emission layer(EML)을 Co-deopsition 하는 방법으로 주로 인광 유기 발광 다이오드를 제작 하였다. [1] co-deposition을 이용해 만든 유기 발광 다이오드에 많은 장점이 있지만, 반대로 소자를 제작하는데 있어서는 많은 문제점을 가지고 있다. [2-4] 이러한 문제점을 개선하기 위하여 co-deposition 대신 non-doped Multi Quantum Well(MQW) 구조를 사용하여 doping 하지 않는 방법을 이용하는 논문들이 보고 되고 있다. Hole, electron, exciton이 MQW 구조를 지나면서, dopant well 안에 갇히게 되고, 그 안에서 다른 layer 간에 energy transfer와, hole-electron leakage가 줄어 들어, 더 효율적인 유기 발광 다이오드를 만들 수 있게 된다. [5-7] 이 연구에서는 CBP를 Potential Barrier로 사용하고, Ir(ppy)3 (Green dopant), Ir(btp)2 (Red dopant) 를 각각 Potential Well로 사용하였고, 두께는 CBP 9nm, dopant 1nm로 하였다. 이러한 소자를 만들고 dopant를 3개의 well에 적당히 배치하여, 각 well에서의 실험적인 발광 량 과, EML 안에서의 발광 mechanism 그리고 각 potential barrier를 줄여가며 dexter, forster에 의한 energy transfer에 대하여 알 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.683-690
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• 1996

The MIDLOOP code has been developed for the evaluation of RES pressurization transients initiated from a loss-of-Residual Heat Removal System (RHRS) during mid-loop operation after reactor shutdown. It provides a fast running and realistic tool for studying parametrically the response of important plant parameters such as pressure, temperature, and level to various plant combinations of the primary side vent, makeup, and leakage procedures and the steam generator (SG) conditions. The code consists of ten nodes representing the primary and secondary sides of a nuclear power plant and can analyze the effect of air on the primary system pressurization and primary to secondary heat transfer. The analysis results of the MIDLOOP code are in good agreement with the ROSA-IV/LSTF experiment without opening in the RCS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.70-71
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• 2009

Photoelectric characteristics of a hydrogenated amorphous silicon thin film transistor(a-Si:H TFT) were obtained for the illumination from various backlight sources and the results were compared and analyzed in terms of the photon energy spectral characteristics of the backlights obtained from the integration of the multiplication of the photon energy and the spectral intensity at etch wavelength. It was possible to conclude that the absorption of illuminated backlight to a-Si:H layer and the generation of electrons and holes are mainly carried out at the wavelength less than 500nm.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1277-1287
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• 2016

This study proposes a novel isolated high step-up galvanic converter, which is suitable for renewable energy applications and integrates a boost converter, a coupled inductor, a charge pump capacitor cell, and an LC snubber. The proposed converter comprises an input inductor and thus features a continuous input current, which extends the life of the renewable energy chip. Furthermore, the proposed converter can achieve a high voltage gain without an extremely large duty cycle and turn ratio of the coupled inductor by using the charge pump capacitor cell. The leakage inductance energy can be recycled to the output capacitor of the boost converter via the LC snubber and then transferred to the output load. As a result, the voltage spike can be suppressed to a low voltage level. Finally, the basic operating principles and experimental results are provided to verify the effectiveness of the proposed converter.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.946-949
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• 1999

In this research we have developed a reliable, effective and feasible HEI(High-Energy Ion Implantation) process 3D-simulation tool, and then by using it we can predict and analyze the effect of HEI process on characteristics of the standard CMOS device. high-energy ion implantation above 200 keV is inevitable process to form retrograde well and buried layer to prevent leakage current, to conduct field implant for field isolation, and to perform after-gate implantation. The feasible analysis tool is a product of the HEI process modeling verified by comparison of the SIMS experiments with the simulation results. Especially, in this paper, we present the predicting capability of HEI-induced impurity and damage profiles compared with the published SIMS data in order to acquire the reliability of our results ranging from few keV to several MeV for phosphorus and boron implantation.