• 조명전기설비학회논문지
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• 제18권3호
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• pp.114-119
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• 2004

차량이라는 특수한 장소에 적용되는 산소 발생 장치는 소형/경량화 및 소음, 충격, 발열에 대한 문제점을 무시할 수 없다. 이러한 문제점을 해결할 방법으로 BLDC를 이용하여 모터의 발열을 줄이고 합성 제올라이트 NaX형을 사용한 베드로 소형에서도 고농도의 산소를 발생시킬 수 있게 하였다. 또한, 합성 제올라이트 NaX형의 특성으로 인한 질소의 강제 탈착을 진공펌프 한 대로 사용하기 위하여 Two Head 진공펌프 Pump Type을 개발하여 소비 전력을 줄이고 소형/경량화 및 저소음, 충격/발열 문제를 해결할 수 있었다.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.76-81
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• 2011

Exhaust gas recirculation is the well-known and widely used NOx reduction technology for diesel engines. More effective EGR cooler has been developed and applied to diesel engines to meet the reinforced emission regulation. However, the contaminated EGR cooler by diesel exhaust gas reduces the performance of the engine and NOx reduction rate. The buildup of deposits in EGR coolers cause significant degradation in heat transfer performance, often on the order of 20~30%. Deposits also increase pressure drop across coolers and thus may degrade engine efficiency under some operation conditions. In this study, as a solution for this problem, DOC assisted EGR cooler is designed and then investigated to reduce fouling and its impact on cooler performance. A single channel EGR cooler fouling test apparatus and soot particle generator were developed to represent the real EGR cooler and exhaust gas of diesel engine. EGR cooler effectiveness of the case with catalyst of pt 30g/ft3 decreased just up to 5%. This value was 45% less compared to the case without catalyst which decreased up to 9% after 10hours experiments.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.403-410
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• 1995

A loss of the residual heat removal (RHR) accident during mid-loop operation of Yong-gwang Nuclear Units 3/4 was analyzed using the RELAP5/MOD3.1.2 code. In this work the following assumptions are used; (i) initially the reactor coolant system (RCS) above the hot leg center line is filled with nitrogen gas, (ii) two 3/4-inch diameter vent valves on the reactor vessel head and the top of pressurizer in the reactor coolant system are always open, and a level indicator is connected to the RMR suction line, (iii) the two steam generators are in wet layup status and the steam generator atmospheric dump valve assemblies are removed so that the secondary side pressure remains at nearly atmospheric condition throughout the accident, and (iv) the loss of RHR is presumed to occur at 48 hours after reactor shutdown. Findings from the RELAP5 calculations are (i) the core boiling begins at ∼5 min, (ii) the peak RCS pressure is ∼3.0 bar, which implies a possibility of temporary seal break, (iii) ∼94 % of the decay heat is removed by reflux condensation in the steam generator U-tubes in spite of the presence of noncondensable gas, (iv) the core uncovery time is evaluated to be 7.2 hours. Significant mass errors were observed in the calculations.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.567-577
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• 2019

Due to the depletion of fossil fuels and environmental pollution, demand for alternative energy is gradually increasing. Among the various methods, a method to convert biomass into alternative fuel has been proposed. The bio-fuel obtained from biomass through pyrolysis process is called pyrolysis oil (PO) or bio-oil. Because PO is difficult to use directly in conventional engines due to its poor fuel properties, various methods have been proposed to upgrade pyrolysis-oil. The simplest approach is to mix it with conventional fossil fuels. However, due to their different polarity of PO and fossil fuel, direct mixing is impossible. To resolve this problem, emulsification of two fuels with a proper surfactant was proposed, but it costs additional time and cost. Alternatively, the use of alcohol fuels as an organic solvent significantly improve the fuel properties such as fuel stability, calorific value and viscosity. In this study, blends of diesel, n-butanol, and coffee ground pyrolysis oil (CGPO) which is one of the promising PO, was applied to diesel generator. Combustion and emissions characteristics of blended fuels were investigated under the entire load range. Experimental results show that ignition delay is similar to that of diesel at high load. Although, hydrocarbon and carbon monoxide emissions are comparable to diesel, significant reduction of nitrogen oxides and particulate matter emissions were observed.

• 항공우주기술
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• 제3권1호
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• pp.251-256
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• 2004

적외선 소자로부터 생성되는 신호와의 비교에 의한 잡음 특성의 향상, 즉 좋은 영상을 얻기 위해서 적외선 영상신호 취득회로(ROIC)에서는 안정적인 기준 전압원이 필요하다. 본 논문은 극저온인 77K에서 동작하는 적외선 영상신호 취득회로(readout integrated circuit)를 위한 밴드갭 기준회로에 대해서 제안하고 있다. 기본에 발표된 대부분의 밴드갭 기준회로는 실온에서 동작하는 것이며, 액체질소 온도 77K에서 동작하는 적외선 영상 ROIC에는 적합하지 않다. 본 논문에서는 극저온에서 동작하는 밴드갭 기준회로 설계를 위하여, 온도변화에 따른 사용되는 소자들의 parameter에 대한 특성을 살펴본 후, 이러한 특성들을 고려하여 밴드갭 기준 회로를 제안하였으며 이것은 그 실용 가능성을 입증하고 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.96-97
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• 2012

In nitride and oxide film deposition, sputtered metals react with nitrogen or oxygen gas in a vacuum chamber to form metal nitride or oxide films on a substrate. The physical properties of sputtered films (metals, oxides, and nitrides) are strongly influenced by magnetron plasma density during the deposition process. Typical target power densities on the magnetron during the deposition process are ~ (5-30) W/cm2, which gives a relatively low plasma density. The main challenge in reactive sputtering is the ability to generate a stable, arc free discharge at high plasma densities. Arcs occur due to formation of an insulating layer on the target surface caused by the re-deposition effect. One current method of generating an arc free discharge is to use the commercially available Pinnacle Plus+ Pulsed DC plasma generator manufactured by Advanced Energy Inc. This plasma generator uses a positive voltage pulse between negative pulses to attract electrons and discharge the target surface, thus preventing arc formation. However, this method can only generate low density plasma and therefore cannot allow full control of film properties. Also, after long runs ~ (1-3) hours, depends on duty cycle the stability of the reactive process is reduced due to increased probability of arc formation. Between 1995 and 1999, a new way of magnetron sputtering called HIPIMS (highly ionized pulse impulse magnetron sputtering) was developed. The main idea of this approach is to apply short ${\sim}(50-100){\mu}s$ high power pulses with a target power densities during the pulse between ~ (1-3) kW/cm2. These high power pulses generate high-density magnetron plasma that can significantly improve and control film properties. From the beginning, HIPIMS method has been applied to reactive sputtering processes for deposition of conductive and nonconductive films. However, commercially available HIPIMS plasma generators have not been able to create a stable, arc-free discharge in most reactive magnetron sputtering processes. HIPIMS plasma generators have been successfully used in reactive sputtering of nitrides for hard coating applications and for Al2O3 films. But until now there has been no HIPIMS data presented on reactive sputtering in cluster tools for semiconductors and MEMs applications. In this presentation, a new method of generating an arc free discharge for reactive HIPIMS using the new Cyprium plasma generator from Zpulser LLC will be introduced. Data (or evidence) will be presented showing that arc formation in reactive HIPIMS can be controlled without applying a positive voltage pulse between high power pulses. Arc-free reactive HIPIMS processes for sputtering AlN, TiO2, TiN and Si3N4 on the Applied Materials ENDURA 200 mm cluster tool will be presented. A direct comparison of the properties of films sputtered with the Advanced Energy Pinnacle Plus + plasma generator and the Zpulser Cyprium plasma generator will be presented.

• 한국산학기술학회논문지
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• 제19권2호
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• pp.617-622
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• 2018

인간의 생명 유지에 가장 필수적인 것은 공기이지만, 산업의 발달 인구의 증가 등으로 도시의 공기는 매연과 유해가스 등으로 오염되고 있다. 이런 이유 등으로 최근 환경문제 중 대기오염에 대한 문제가 크게 다루어지고 있다. 공기청정기와 함께 쾌적한 실내공기를 제공할 수 있는 또 하나의 기기는 산소발생기이다. 산소발생기의 주 원리는 합성 제올라이트를 이용하여 공기로부터 산소를 분리하는 데에 있다. 다양한 합성 제올라이트들은 그들이 갖고 있는 특성을 이용하여 실생활에 유용하게 적용되어지고 있다. 이런 제올라이트의 특성 중 질소를 흡착하는 성질을 이용하여 대기 중의 질소를 흡착 시킨 뒤 산소만을 발생시켜 산소발생기에 적용시킬 수 있다. 그리하여 우리는 5가지 종류의 천연제올라이트와 LTA 제올라이트, 3A, 4A, 5A(크기가 다른 두 가지)를 사용하여 각각의 질소흡착정도를 알아보고자 하였다. PSA 방식을 사용하여 질소흡착정도가 높을수록 산소포화농도가 높게 나오는 원리를 통해 5A(양이온이 칼슘으로 보충된 LTA제올라이트) 제올라이트의 질소흡착정도가 평균 6% 증가하여 가장 크다는 것을 알 수 있었고 또한 제올라이트의 크기에도 많은 영향을 받는다는 것을 알 수 있었다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1994년도 춘계학술발표회 초록집
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• pp.91-97
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• 1994

본 연구의 목표는 제올라이트 분자체를 흡착제로 사용하여 99.99% 이상의 고순도 질소를 저렴하게 제조하는 PSA(Pressure Swing Adsorption)공정을 개발하고 상업화 설계 자료를 도출하는 것이다. PSA방법에 의한 질소제조는 기존의 심냉법보다 전력원단위가 낮을 뿐만 아니라 on-site방식으로 설치되어 운영되므로 수송경비를 절감할 수 있다. 이러한 장점 때문에 외국의 경우를 보면 PSA의 사용이 날로 증대되고 있다. 현재 국내에 설치중인 질소 PSA는 전량 수입에 의한 것이다. 따라서 본 연구에서 개발한 질소 PSA는 중소규모의 질소가스 사용처에 공급함으로써 에너지절감효과 뿐만아니라, 수입대체효과도 얻을 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.181-185
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• 2008

The new concept for liquefaction of natural gas has been designed and simulated in this paper. Conventional liquefaction cycles are usually composed with Joule-Thomson valves at lower temperature refrigerant cycle. The new concept of natural gas liquefaction is discussed. The main difference with conventional liquefaction process is the presence of the turbine at low temperature of MR (mixed refrigerant) cycle. The turbine acts as expander but also as an energy generator. This generated energy is provided to the compressor which consumes energy to pressurize refrigerants. The composition of the mixed refrigerant is investigated in this study. Components of the refrigerant are methane, propane and nitrogen. Composition for new process is traced with Aspen HYSYS software. LNG heat exchangers are analyzed for the new process. Heating and cooling curves in heat exchangers were also analyzed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.134-134
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• 2011

High-k dielectric materials such as $HfO_2$, $ZrO_2$ and $Al_2O_3$ increase gate capacitance and reduce gate leakage current in MOSFET structures. This behavior suggests that high-k materials will be promise candidates to substitute as a tunnel barrier. Furthermore, stack structure of low-k and high-k tunnel barrier named variable oxide thickness (VARIOT) is more efficient.[1] In this study, we fabricated the $WSi_2$ nanocrystals nonvolatile memory device with $SiO_2/HfO_2/Al_2O_3$ tunnel layer. The $WSi_2$ nano-floating gate capacitors were fabricated on p-type Si (100) wafers. After wafer cleaning, the phosphorus in-situ doped poly-Si layer with a thickness of 100 nm was deposited on isolated active region to confine source and drain. Then, on the gate region defined by using reactive ion etching, the barrier engineered multi-stack tunnel layers of $SiO_2/HfO_2/Al_2O_3$ (2 nm/1 nm/3 nm) were deposited the gate region on Si substrate by using atomic layer deposition. To fabricate $WSi_2$ nanocrystals, the ultrathin $WSi_2$ film with a thickness of 3-4 nm was deposited on the multi-stack tunnel layer by using direct current magnetron sputtering system [2]. Subsequently, the first post annealing process was carried out at $900^{\circ}C$ for 1 min by using rapid thermal annealing system in nitrogen gas ambient. The 15-nm-thick $SiO_2$ control layer was deposited by using ultra-high vacuum magnetron sputtering. For $SiO_2$ layer density, the second post annealing process was carried out at $900^{\circ}C$ for 30 seconds by using rapid thermal annealing system in nitrogen gas ambient. The aluminum gate electrodes of 200-nm thickness were formed by thermal evaporation. The electrical properties of devices were measured by using a HP 4156A precision semiconductor parameter analyzer with HP 41501A pulse generator, an Agillent 81104A 80MHz pulse/pattern generator and an Agillent E5250A low leakage switch mainframe. We will discuss the electrical properties for application next generation non-volatile memory device.