• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.154-154
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• 2015

현재 액체로켓 엔진 연소기 내벽은 bonding layer NiCrAlY과 Top layer $ZrO_2$가 플라즈마 용사 방식으로 형성 된다. 이는 뛰어난 열 차폐 특성과 작업시간이 짧은 장점이 있지만, bonding layer와 Top layer 사이의 열팽창 계수 차이로 인한 균열 발생 가능성이 내재 되어 있고, 연소실 내벽에 균일한 두께의 코팅층을 형성하기 어렵고 설비가 비싸다는 단점으로 인하여 세라믹 코팅 층을 금속 코팅 층으로 대체 하고자 한다. 금속 코팅층은 모재와의 밀착성이 높고, 우수한 산화 및 부식방지 기능을 가지며 저렴하다는 장점이 있다. 또한 코팅 후 연마 작업이 가능해 연소실 내부형상을 설계조건 대로 유지 할 수 있는 특징이 있다. 따라서 본 연구에서는 연소실 내벽에 적용할 모재, 무전해 Ni-P 도금과 전해 Cr 도금층 사이의 밀착력 향상을 위한 방법에 대한 연구를 하였다. 밀착력 향상을 위한 요소로 전처리 용액과 열처리 시간에 따른 영향을 알아보고자 하였으며, 이를 위해서 5가지의 산세 용액으로 각 시편을 산세 한 후, 6시간, 12시간, 18시간 열처리 하여 단면을 비교하여 열처리에 영향을 알아보고자 하였다. 연구 결과 산세 용액의 영향은 크게 나타나지 않았으며, 열처리 시간이 길수록 Ni-P/Cr의 확산이 더 잘 일어나 확산층이 더 넓어지면서 밀착력이 더 좋아 진 것으로 판단되어 진다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.127-130
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• 2007

Skin detection research is important role in the 3G of mobile phone for video telephony and security system by using face recognition. We propose skin detection algorithm as preprocessing to the face recognition, and use YCbCr color space. In existing skin detection algorithm using CbCr, skin colors that is brightened by camera flash or sunlight at outdoor in images doesn't acknowledged the skin region. In order to detect skin region accuracy into any circumstance, this paper proposes 3-channel skin detection algorithm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.200-200
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• 2003

고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기 위하여 사용된다. SOFC용 연결재는 다른 구성요소 소재보다, 높은 전자 전도성, 낮은 이온전도성, 우수한 기계 적강도가 요구되며, SOFC는 고온에서 작동되기 때문에, 상온에서 작동온도까지 다른 요소 소재들과 유사한 열팽창계수와 물리, 화학적으로 안정성이 요구된다. 현재 연결재 제조기술은 EVD, CVD, plasma spraying, tape casting 등 다양하게 연구되고 있으며, 본 연구는 세라믹 연결재 증착방법 중 저렴한 비용으로 대량 생산이 용이한 습식법(dip coaling)을 적용하여, 연료극 지지체식 flat-tube형 고체산화물 연료전지의 지지체를 위해 세라믹 연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로써 선정한 합성조성은 LaCr $O_3$에 Ca이 치환 고용된 L $a_{0.6}$C $a_{0.41}$Cr $O_3$으로 pechini법으로 합성하였다. 합성된 조성은 100$0^{\circ}C$에서 5시간 하소후 가속 Ball Milling하여 0.5$\mu\textrm{m}$의 평균입자크기를 얻을 수 있었다. XRD 상분석결과 perovskite상 (L $a_{1-x}$ Ca/x/Cr $O_3$)과 CaCr $O_4$를 얻을 수 있었다. slurry를 제조하여 막의 밀착성을 증진시키기 위해 sand blasting시킨 flat tube지지체에 진공펌프를 이용하여 소재내부와 외부의 압력차로 dip coating한 후, 140$0^{\circ}C$로 소결 하였다. coating 결과 박리현상은 없었으나, 표면과 단면의 SEM분석결과 다소 porous한 박막층이 형성되었으며, Ca이온이 지지체로 permeation되는 현상이 발생하였다. 이와 같은 결과로부터 보다 치밀한 박막생성을 위해, slurry 제조조건을 변화시켰으며, Ca이온의 migration을 막기 위해 barrier layer를 이용하였다 완전 소결된 지지체는 가스투과도와 전기전도도측정을 통하여 특성을 평가하였다.였다.다.

• Elastomers and Composites
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• v.49 no.4
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• pp.293-304
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• 2014

Rubber air spring (RAS) is a special suspension device for the industries of automobile, railroad car and other transportation. A RAS serves as a spring component with the elastic effect of compression and expansion of air in a composite rubber bag. The main component of RAS is the rubber sleeve. Rubber sleeve is the composite which is made up of combination of chloroprene rubber (CR) and nylon 6 cord, and the adhesive strength between CR and nylon 6 cord is very important. In this study, considering the effects of additives in rubber sleeve, various physical properties were tested to find the optimal combination of composition and conditions. Further, in order to select the optimum orientation of the reinforcing fibers, numerical analysis was performed using the finite elements method. After assembling all components of RAS, it was mounted on an actual vehicle, and then it was tested air leakage, fatigue life and fundamental properties.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.34-41
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• 1998

In this paper, we evaluate synchronization techniques suitable for high-speed ATM satellite communications with a transmission rate of 155Mbit/s, and propose optimal algorithms that improve the tracking performance, where QPSK is selected for a modulation scheme, and the receiver is operated in burst mode. Based on these asumptions, we proposed modified algorithms and architectures for automatic frequency control(AFC), carrier recovery(CR), and symbol timing recovery(STR) for burst acquisition. Analysis is performed under AWGN environments with respect to the number of required symbol, steady-state stability, and hardware implementation for the proposed algorithms.

• Journal of the Korea Society of Computer and Information
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• v.14 no.8
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• pp.145-152
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• 2009

Manufacturer's competitiveness in the MRO industry, which is to stimulate the growth of the business-to-business e-commerce market, has recently become more important. A nuclear parts manufacturer was supplying products based on irregular demand from clients which differs from ordinary MRO business practices. The reason for this is the Nuclear Parts Manufacturer has fallen behind the e-commerce performance of other industries, and they lack global competitiveness due to the low efficiency of the individual companies within it. In this study, we developed an MRO based a-Marketplace system to minimize repetitive ordering of raw materials, lack of reusability and inefficiency of transaction processing which was a result of the former legacy business practice, In order to accomplish the purpose of this study, we implemented a web based automated CR system which considered the characteristics of the nuclear parts manufacturing: the system has sub modules such as ordering, product management, transaction management, warehousing and raw material handling. As a consequence of the system implementation, H corporate successfully automated ordering of raw materials, quotation processing and inventory management compared to the legacy business process, achieving increased efficiency by reducing wasteful resources.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.388-394
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• 2005

This paper has the object of investigating natural frequencies of tapered thick plate on Pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Vibration analysis for tapered thick plate subjected to in-plane stress is presented in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. Analysis conditions of tapered thick plate are as follows each. The ratio of in-plane stress to critical load is varied with $0.2\sigma_{cr}$, $0.4\sigma_{cr}$, $0.6\sigma_{cr}$. The Winkler parameter is 0, 10, 100, 1000, the shear foundation parameter is 0, 10 and the taper ratio is 0.0, 0.2, 0.4, 0.6, 0.8.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.501-505
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• 2007

현재 기술 동향에 따라, 언제 어디서나 통신 및 컴퓨팅이 가능한 유비쿼터스 컴퓨팅 시스템(Ubiquitous Computing System)을 위해 사용자 및 주변 환경의 상황을 인식하는 기술(Context-Aware Computing System)이 필수적인 요소로 부각되고 있다. 하지만, Context-Aware Computing System을 구현하기 위해서 사용자 및 주변 환경으로부터 입력되는 불확실하거나 모호한 상황정보에 대한 표현과 추론에 대한 연구는 부족한 실정이다. 이를 해결하기 위해 Rule-based System을 기반으로 CRS와 DOS의 개념을 도입하여 상황인식 기술을 SoC로 구현할 수 있도록 새로운 Architecture를 제안한다. 마지막으로는 CRS와 DOS가 Network Topolgy에 적용된 RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol)의 예를 통해 그 효용성을 입증하고, Ubiquitous Computing System에서 활용 가능한 방법 등을 제시한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1296-1305
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• 2009

This paper has the object of investigating dynamic stability of stiffened tapered thick plate with concentrated mass on Pasternak foundation by means of finite element method and providing kinematic design data for mat of building structures. Finite element analysis of stiffened tapered thick plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on Pasternak foundation, the Winkler foundation parameter is varied with 10, 100, 1000 and the shear foundation parameter is 5, 10, concentrated mass is $0.25m_c$, $1.0m_c$, tapered ratio is 0.25, 0.5. The ratio of In-plane force to critical load is applied as $0.4\sigma_{cr},\;0.6\sigma_{cr},\;0.8\sigma_{cr}$ respectively. This paper analyzed varying tapered ratio.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.839-853
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• 1998

The present study was performed to prove the relationship between CO-CR discrepancy and facial skeletal type. In this study, 242 subjects were randomly selected and devided into 9 groups(devided into class I, II, III by ANB and each one devided into dolicho-, brachy-, mesofacial skeleton by Ricketts' vertical index). Lateral cephalometric radiographs with the mandible in centric occlusion were taken and measured and CO and CR bites were registered on all subjects. Diagnostic casts were mounted on Panadent articulator using an estimated face-bow and centric relation bite registration. The amount and direction of CO-CR discrepancy present was recorded using a Condylar Position Indicator(CPI) and a centric occlusion wax bite registration. CPI measurements and cephalometric measurements were statistically analyzed. The finding of this study can be summerized as follows : 1. There is little correlation between right and left sides for magnitude or direction of CO-CR discrepancies. The correlation between the magnitude of CO-CR discrepancy of left A-P and right A-P is higher than that of left S-I and right S-I. 2. Correlation of Class II malocclusion group was higher than that of the other groups between the magnitude of CO-CR discrepancy of left CPI and right CPI. 3. There is no difference between the pattern of CO-CR discrepancy of 9 malocclusion groups. 4. There is very little, if any, correlation between Skeletofacial measurements and CO-CR discrepancy. 5. In Class II brachyfacial skeleton and Class III mesofacial skeleton there was Lateral cephalometric measurements by that we predict CPI measurements was detected. That was overbite, overjet, upper genial angle, lower genial angle, saddle angle, articular angle, convexity of point A, ANS-Me/Na-Me, PCBL/RH, Posterior FH/anterior FH.