• Smart Structures and Systems
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• 제24권6호
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• pp.803-812
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• 2019

Triplex composite is an epoxy-bonded joint structure, which constitutes the secondary barrier in a liquefied natural gas (LNG) carrier. Defects in the triplex composite weaken its shear strength and may cause leakage of the LNG, thus compromising the structural integrity of the LNG carrier. This paper proposes an autonomous triplex composite inspection (ATCI) system for visualizing and classifying hidden defects in the triplex composite installed inside an LNG carrier. First, heat energy is generated on the surface of the triplex composite using halogen lamps, and the corresponding heat response is measured by an infrared (IR) camera. Next, the region of interest (ROI) is traced and noise components are removed to minimize false indications of defects. After a defect is identified, it is classified as internal void or uncured adhesive and its size and shape are quantified and visualized, respectively. The proposed ATCI system allows the fully automated and contactless detection, classification, and quantification of hidden defects inside the triplex composite. The effectiveness of the proposed ATCI system is validated using the data obtained from actual triplex composite installed in an LNG carrier membrane system.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.146-153
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• 2013

CNG buses has contributed to improve air quality in cities. But it is difficult to meet the next emission regulations such as EURO-VI without the help of additional post-processing device. Hydorgen has higher flame speed and lower combustion temperature that make it thermal efficiency increase with leaner operation. Using hydrogen natural gas blend (HCNG) fuel is promising technology which can reduce $NO_x$ and $CO_2$ emissions for a natural gas vehicle. However, fuel flow rate of HCNG should be increased since hydrogen's energy density per volume is much smaller than natural gas. In the present study, the characteristics of fuel supply system and its applicability were evaluated in a heavy duty natural gas engine. The results showed that the potential of fuel pressure regulator and fuel metering valve had enough capacity with HCNG. Employed mixer did not affect the distribution characteristics of mixture.

• 한국가스학회지
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• 제14권1호
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• pp.42-46
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• 2010

LNG (Liquefied Natural Gas)기지의 LNG 저장탱크에서 BOG (Boil Off Gas)가 약 0.5 vol%/day로 자연적으로 생성된다. 이를 회수하기 위해서 기존에는 LNG와 BOG를 1:12의 질량비로 직접 접촉시켜 액화시켰다. 이 공정은 단순하지만 하절기에는 LNG 사용량 저하로 인해 공정운영의 어려움이 있다. 이러한 단점을 보완하기 위해 대안된 LNG 냉열을 사용하는 간접접촉방식을 HYSYS를 이용하여 분석해보고 직접접촉방식과 BOG 재액화 효율비교를 통해 분석하여 유리한 공정을 도출하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.1-6
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• 2002

Plasma processing of semiconductor materials plays a dominant role in microelectronic technology. During last century, plasma have gone a way from laboratory phenomena to industrial applications due to intensive progress in both scientific and industrial trends. Improvement and development of new experience together with development of plasma theory and plasma diagnostics methods. A most parameters (pressure, flow rate, power density) and various levels of plasma system (energy distribution, volume gas chemistry, transport, heterogeneous effects) to understand the whole process mechanism. It will allow us to choose a correct ways for processes optimization.

• 한국가시화정보학회지
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• 제2권1호
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• pp.25-31
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• 2004

Droplet size is one of the most important parameter which controls the performance of the combustion system using liquid fuel or oxidizer. Droplet formation and its size are mainly affected by the injection velocity and ambient gas density. Recently, droplet size measurement was conducted by PDPA or Malvern particle analyzer using laser light. But at this paper image processing method was developed to measure droplet size. And its validation was investigated with reticle.

• 반도체디스플레이기술학회지
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• 제1권1호
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• pp.9-13
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• 2002

A polyimide-type electrostatic chuck (ESC) was fabricated for the application of holding 8-inch silicon wafers in the oxide etching equipment. For the fabrication of the unipolar ESC, core technologies such as coating of polyimide films and anodizing treatment of aluminum surface were developed. The polyimide films were prepared on top of thin coated copper substrates for the good electrical contacts, and the helium gas cooling technique was used for the temperature uniformity of the silicon wafers. The ESC was essentially working with an unipolar operation, which was easier to fabricate and operate compared to a bipolar operation. The chucking force of the ESC has been measured to be about 580 gf when the applied voltage was 1.5 kV, which was considered to be enough force to hold wafers during the dry etching processing. The employment of the ESC in etcher system could make 8% enhancement of the wafer processing yield.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 추계학술발표대회
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• pp.919-920
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• 2009

액화 천연 가스 플랜트 시뮬레이터는 막대한 자본 투자가 필요한 대형 시스템 설계 및 건설 단계에서 사전에 설계 오류 검출 및 시스템 검증을 함으로써 많은 비용을 절약해줄 수 있는 중요한 시스템이다. 이 연구에서는 플랜트, 시뮬레이터, 운전원 훈련 시스템 및 제어시스템을 운전하는 과정에서 발생하는 정보를 효과적으로 처리하기 위해서 구축되는 정보 처리 시스템의 기본 설계에 관한 내용을 소개한다. 전체 시스템은 물리적 플랜트와 가상 플랜트로 나눌 수 있고 가상 플랜트는 시뮬레이터와 운전원 훈련 시스템으로 구현되며, 제어 시스템은 PLC로 구현하고 Modubus 프로토콜과 OPC 서버를 통해 데이터 처리가 가능하다. 플랜트로부터 생성되는 데이터 처리에서는 실시간 데이터 처리 속도가 중요하므로 실시간 데이터베이스를 도입하였다. 실제 플랜트 데이터와 시뮬레이터 데이터는 상호 교환이 가능하도록 구성하였다. 본 시스템 설계는 기본 설계 단계이므로 향후 LNG 플랜트에 적용하기 위해서는 상세 설계가 필요하다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.440-447
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• 2002

본 연구에서는 호흡량 측정에 영향을 주는 요인들로부터 정확한 유량을 산출해내는 방법에 대해 고찰하고, 마취용 인공호흡기에 적용하여 수술환자의 호홉특성을 알아내는 호흡측정기를 구현하였다. 차동압력형 유량센서를 이용하여 압력, 온도, 가스구성의 상관관계에 따라 호흡량을 계측하였으며, 휴대형 기기에 적합하도록 전력 효율을 최대화 할 수 있게 시스템을 설계하였다. 구현 시스템은 크게 아날로그 인터페이스(analog interface)부, 신호처리부, 그리고 화면출력부로 나눌 수 있다. 아날로그 인터페이스부는 차동 압력 유량 센서와 차동 압력 센서로 구성된다. 전력소모를 최소화하기 위하여 여러 가지 기능을 단일소자로 수행할 수 있고, 저전력의 8비트 RISC 계열인 AVR프로세서를 중앙처리장치로 선택하였다. 데이터 전송부에서는 직렬(serial)통신(RS232, SPI)으로 측정된 값들의 출력 파형을 PC화면에 표시하거나 마취기로 전송한다. 차동 압력과 유량의 비선형적 관계를 선형화하였고, 센서 보정 기능은 일정 주기로 보정을 자동적으로 수행함으로써, 보다 안정적인 동작이 가능하게 한다. 아날로그 필터와 고속의 디지털 신호처리 알고리즘 구현으로 생체신호의 노이즈를 줄일 수 있었다. 작고, 가벼우며, 저전력인 시스템의 특징은 응급 환자나 이동중인 환자에게 적용될 수 있으며, 가래, 침, 습기와 같은 이물질에 영향이 적은 유량 센서의 사용으로 점액의 발생이 많은 마취기에서 유용하게 사용될 수 있다.

• Journal of Biosystems Engineering
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• 제38권4호
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• pp.306-311
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• 2013

Purpose: With the ever-rising energy prices, thermal energy heavily consuming facilities of the agricultural sector such as commercialized greenhouses and large-scale Rice Processing Complexes (RPCs) need to cut down their energy cost if they must run profitable businesses continually. One possible way to reduce their energy cost is to utilize combustible agricultural by-products or low-price oil instead of light oil as the fuel for their boiler systems. This study aims to analyze the heavy oil combustion characteristics of a newly developed hot water boiler system that can use both rice husk and heavy oil as its fuel convertibly. Methods: Heavy oil combustion experiments were conducted in this study employing four fuel feed rates (7.6, 8.5, 9.5, 11.4 $l/h$) at a combustion furnace vacuum pressure of 500 Pa and with four combustion furnace vacuum pressures (375, 500, 625, 750 Pa) at fuel feed rates of 9.5 and 11.4 $l/h$. Temperatures at five locations inside the combustion furnace and 20 additional locations throughout the whole hot water boiler system were measured to ascertain the combustion characteristics of the heavy oil. From the temperature measurement data, the thermal efficiency of the system was calculated. Flue gas smoke density and concentrations of air-polluting components in the flue gas were also measured by a gas analyzer. Results: As the fuel feed rate or combustion furnace vacuum pressure increased, the average temperature in the combustion furnace decreased but the thermal efficiency of the system showed no distinctive change. On the other hand, the thermal efficiency of the system was inversely proportionally to the vacuum level in the furnace. For all experimental conditions, the thermal efficiency remained in the range of 80.1-89.6%. The CO concentration in the flue gas was negligibly low. The NO and $SO_2$ concentration as well as the smoke density met the legal requirements. Conclusions: Considering the combustion temperature characteristics, thermal efficiency, and flue gas composition, the optimal combustion condition of the system seemed to be either the fuel feed rate of 9.5 $l/h$ with a combustion furnace vacuum pressure of 375 Pa or a fuel feed rate of 11.4 $l/h$ with a furnace vacuum pressure between 500 Pa and 625 Pa.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.156.1-156.1
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• 2011

It is of great importance to predict operating parameter characteristics of an integrated fuel processor by the increased life-time and system performance. In this study, computational analysis is performed to gain fundamental insights on transport phenomena and chemical reactions in reformer which consists of preheating, steam reforming, and water gas shift reaction beds. Also, a top-fired burner locates inside of the reforming system. The combustor is providing thermal energy necessary for the steam reforming bed which is a endothermic catalytic reactor. Two-dimensional numerical model of the integrated fuel processing system is introduced for the analysis of heat and mass transport phenomena as well as surface kinetics and catalytic process. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Subsequently, parameter study using the validated steam methane reforming model was conducted by considering operating parameters, i.e. steam to carbon ratio and temperature.