• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.508-514
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• 2004

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 ${\mu}{\textrm}{m}$, 250 ${\mu}{\textrm}{m}$, and 500 ${\mu}{\textrm}{m}$ were designed in a rectangular-ring shaped core and the gaps of 0 ${\mu}{\textrm}{m}$, 50 ${\mu}{\textrm}{m}$, and 100 ${\mu}{\textrm}{m}$ were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 ${\mu}{\textrm}{m}$ width and 6${\mu}{\textrm}{m}$ thickness were electroplated on Ti(300 $\AA$) / Cu(1500 $\AA$) seed layers. 3 ${\mu}{\textrm}{m}$ thick N $i_{0.8}$F $e_{0.2.}$(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 ${\mu}{\textrm}{m}$ side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 $V_{P-P}$ and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0${\times}$1.7 $\textrm{mm}^2$. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.

• 에너지공학
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• 제28권4호
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• pp.103-110
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• 2019

국내에서 개발 중인 차세대 혁신형 안전경수로인 iPOWER는 피동용융노심냉각계통의 도입을 통해 중대사고시 노심용융물을 원자로 하부에서 장기간 냉각하고 안정화시키고자 한다. 아직 피동용융노심냉각계통의 최종 설계개념이 확정되기 전이나, 원자로용기 외벽냉각을 통한 노심용융물의 노내 억류 역시 주요 중대사고 대처 전략의 하나로 검토되고 있다. 본 연구에서는 국내에서 개발된 열수력 계통해석코드인 MARS-KS를 이용하여 원자로용기와 단열체 사이에서 형성되는 2상 자연순환 유동을 모의하였다. 냉각수의 유로를 일차원으로 모델링하고, 노심용융물의 열부하에 따른 경계조건을 정의하여 자연순환 유량을 계산하였다. 또한 냉각수의 온도 및 수위, 원자로용기 하반구 주변 기포율 및 외벽에서의 열전달모드 등 주요 열수력 변수의 과도거동을 평가하였다.

• 공업화학
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• 제23권1호
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• pp.77-85
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• 2012

팽창진주암(expanded perlite)과 섬유상 해포석(sepiolite)과의 복합화를 통해 유연성을 지닌 세라믹 발포체의 제조가능성을 조사하였다. 무기광물 섬유 해포석의 해섬처리는 팽창진주암과 해포석으로 이루어진 세라믹발포체의 제조를 위해 가장 중요한 전 처리공정이다. 해섬된 해포석과 팽창진주암은 혼합 교반되어 슬러리 상태로 이루어지며, 이 슬러리상의 복합물은 $300^{\circ}C$ 이하의 저온 열처리과정을 통해 형상화 및 발포화되어 괴상의 발포체로 제조된다. 슬러리상 복합물의 열처리공정은 슬러리 복합물 중에 잔존하는 수분의 증발단계, 일정발포온도에서 발포화제가 분해되어 진행되는 발포화단계 및 발포 후 잔류되는 유기물질의 분해제거단계를 포함하는 것으로 설계되어야 한다. 열처리 공정조건과 발포제는 상관성이 있으며 팽창진주암과 해포석섬유로 이루어진 슬러리상 혼합물의 발포에 적절한 발포제는 유기계 발포제가 적절하며 DSS (dioctyl sodium sulfosuccinte)가 효과적이었다.

• 한국염색가공학회지
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• 제29권3호
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• pp.105-114
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• 2017

High tenacity polyethylene(HTPE) fiber is one of the most important synthetic fibers which possesses outstanding properties such as low density, excellent surface hardness and scratch resistance, superior electrical insulation and low cost. In this study, we dyed high tenacity polyethylene filaments using three different solvent dyes based on log P calculations. We evaluated the dyeing characteristics of dyed high tenacity polyethylene filaments based on dyeing temperature, dyeing time and concentration of solvent dyes. We also analyzed the tensile strength and elongation properties of dyed high tenacity polyethylene filaments with various dyeing temperature and dyeing times. The optimized dyeing condition can be found at $120^{\circ}C$ for dyeing time of 1 hour with 4%(o.w.f.) of solvent dyes.

• 한국초전도ㆍ저온공학회논문지
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• 제14권3호
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• pp.9-12
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• 2012

Usually, the AC loss from the superconducting element of an SFCL due to the load current is very small because it is composed of the combination of bifilar windings with very small reactance. Although the AC loss is small enough, we should be albe to predict for the design and control of the cryogenic system. In fact, an SFCL for the transmission voltage class may not generate ignorable AC loss because of the inevitable space between the HTS wires for the high voltage insulation and cryogenic efficiency. To measure the AC loss dependency on the space between the 2G HTS wires with the width of 4.4 mm, we prepared an experimental setup which could adjust the distance between the wires. We used two 500-mm length HTS wires in parallel and applied the current in the opposite direction for each wire to simulate a part of a current limiting module for a high voltage SFCL. We also put two couples of voltage taps at the ends of each wire and a cancel coil in the voltage measurement circuit to compensate the reactive component from the voltage taps. In this condition, we varied the distance between the wires to investigate the change of the transport current loss. A similar experimental study with HTS wire with the width of 12 mm is now in progress.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.288-293
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• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.

• 공학논문집
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• 제2권1호
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• pp.125-131
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• 1997

유리용해로의 축열실은 폐연소가스로 열을저장하며, 유리용해로에 유입되는 흡입공기를 예열시키는 역할을 한다. 유리용해산업에서 연료소비를 줄이기 위하여 절연법, 단열벽돌, 공기누출등이 오래 연구되었다. 또한 새로운 형태의 단열벽돌과 Rider arch가 유리용해로의 수명연장을 위하여 연구되고 있다. 본 연구는 연구대상공장의 이전설치시 유리용해로의 축열실이 5.64m에서 7.89m로 높이가 높아졌고 이에 따른 축열실 하중증가에 의하여 Rider arch가 더 높은 응력을 받게 되었다. 이런 조건에서 Rider arch의 기계적 안정성을 본 연구에서 검토하였다. 계산식에 의하면 하중증가에 따른 Rider arch의 응력은 안정한 것으로 평가되었고 Rider arch가 견딜수 있는 최대 압축응력은 163kg/$cm^2$이고, 최대전단응력은 6.37kg/$cm^2$이다.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.609-615
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• 2011

A 5 kW class SOFC system for cogeneration power units was consisted of a hot box part and cold BOPs. High temperature components such as a stack, a fuel reformer, a catalytic combustor, and heat exchanges are arranged in the bot box considering their operating temperatures for the system efficiency. The hot box was made of ceramic boards for the thermal insulation. A 5 kW class SOFC stack was composed of 2 sub-modules and each module had 64 cells with $15{\times}15cm^2$ area and stainless steel interconnects. The 5 kW class SOFC system was operated with a hydrogen and a city gas. With a hydrogen, the total power of the stacks was about 7.1 kWDC and electrical efficiency was about 49.3% at 80 A. With a city gas, the total power of the stacks was about 5.7 $kW_{DC}$ and electrical efficiency was about 38.8% at 60 A. Under self-sustained operating condition, the system efficiency including a power conditioning loss and a consumed power by BOPs was about 30.2%.

• 전기학회논문지P
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• 제57권2호
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• pp.146-152
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• 2008

The frequency of lightning is increased due to improbable weather condition and global wanning. This phenomenon increases economical damage as well as human damage. Advanced countries like europe and north america have applied the facility standard of lightning by accumulating a store of quantitative data about lightning research. Lightning facility is composed of the lightning accepting part for induction lightning, ground connected electrode which conducts lightning current. The lightning accepting part is composed of normal rod, horizontal conductor, ESE lightning rod. Moreover, lightning accepting part is taken to use by the method of protection. This paper suggests HEC(Hybrid ESE-Conductor) method which mixes horizontal conductor and ESE lightning rod. This is also discovered by experiment that the starting point of corona discharge current is low, so it is efficient for lightning protection comparing with other methods. Moreover, distribution of electric field is analyzed qualitatively by finite element method. It also results in the relation of the starting point of corona discharge current. Corona discharge current makes minute current about some ${\mu}A$ between the electrodes by the strength of electric field. Also it occurs insulation destruction of gas, and it is developed to the shape of streamer by increase of the strength of electric field. We can find that the initial occurrence of streamer and contact probability of lightning can have advantage after researching the starting point of corona discharge current and discharge current of lightning striking point. This research demonstrates that the suggested HEC method is economically competitive as a lightning protection facility, and it takes a capably perfect role.

• 설비공학논문집
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• 제20권7호
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• pp.492-499
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• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.