• 한국통신학회논문지
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• 제18권2호
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• pp.207-217
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• 1993

본 논문에서는 송신된 확산부호와 수신기 내의 기준 확산부호 사이의 위상차에 대한 사전 확률을 알고 있을 때, 동기가 맞을 확률이 높은 셀부터 낮은 셀의 순서로 검사하는 Expanding Window Search 방법을 이용하여 직접확산(Direct Sequence) 통신 시스팀의 초기동기 과정의 상태도를 구성한다. 각 검색에서 앞선 검색 때보다 증가하는 윈도우를 초항이 a고 공비가 r인 등비 수열의 형태로 증가하도록 하였으며, 마코프처리(Markov process)와 메이슨 이득공식(Mason’s gain formula)을 이용하여 상태도를 해석하고 평균 시간을 구한다. 그리고 검색 횟수 n과 검출 확률 $P_d$의 변화에 따른 평균동기 시간의 증감을 사전 확률이 없을 때의 평균등기 시간과 비교한다.

• Design & Manufacturing
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• 제12권1호
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• pp.26-30
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• 2018

The aluminum chassis drive gear manufacturing process improvement has been very effective in both technical and economic aspects. Technology for Shear mold design technology, mold material selection and processing technology, and press molding technology has improved greatly overall. In the meantime, it is necessary to clarify the causes of defects that occur frequently due to lack of technology, Based on this, it is meaningful that it has secured the ability to respond to new product development and molding in the future. By applying these technologies, we plan to expand not only the drive gear chassis, but also various types of press forming such as frame, handle, various fastening parts of system window. In addition, the ability to develop precision products in the future is expected to become a driving force in further enhancing the competitiveness of companies.

• Journal of Information Technology Applications and Management
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• 제21권4호
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• pp.295-308
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• 2014

Global trading is an intrinsically complex endeavor with a number of parties involved. World-trading related international organizations have suggested that Single Window (SW) be used as a means to make the trading process simpler and smoother. However, since each firm has its own requirements and objectives with SW, yet there is no consensus as to what traits of 'good' Single Window are. This study uses IT appropriateness as a determinant to explain an impact on information systems success. Historically, IS success was understood as multi-dimensional constructs such as use and performance. In this study we propose another dimension, continuance, and investigate the relationships among these outcome constructs.

• 전기학회논문지
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• 제59권12호
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• pp.2298-2305
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• 2010

The paper presents the Model Based Design(MBD) method which design and verify control algorithm for safety power window. Safety power window are required to work together with the anti-pinch function and have to meet FMVSS118 S5 requirements and equivalent ECC requirements. To meet the requirements, this paper presents the establishment of SILS and RCP environments. The design process can reduce time and support more performance-assured design. As a result of study, it met the regulations and achieved reaction force that close to common products.

• 한국분말재료학회지
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• 제31권2호
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• pp.137-145
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• 2024

In order to predict the process window of laser powder bed fusion (LPBF) for printing metallic components, the calculation of volumetric energy density (VED) has been widely calculated for controlling process parameters. However, because it is assumed that the process parameters contribute equally to heat input, the VED still has limitation for predicting the process window of LPBF-processed materials. In this study, an explainable machine learning (xML) approach was adopted to predict and understand the contribution of each process parameter to defect evolution in Ti alloys in the LPBF process. Various ML models were trained, and the Shapley additive explanation method was adopted to quantify the importance of each process parameter. This study can offer effective guidelines for fine-tuning process parameters to fabricate high-quality products using LPBF.

• 한국통신학회논문지
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• 제32권6A호
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• pp.550-557
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• 2007

인과 관계에 대한 직관적인 개념으로 Bayesian Networks 알고리즘이나 트리 구조 추측 알고리즘 그리고 유전자 알고리즘을 사용하여 다양한 구조의 상황을 예측을 하게 된다. 하지만 이런 예측 알고리즘들을 상황인지 서비스 구현에 적용하기에는 실제 구현의 어려움과 실시간 환경에서 트레이닝 데이터 처리에서 오는 시간 지연 문제 등이 발생하게 된다. 이 때문에 특정 목적의 상황인지 시스템에서 이 알고리즘들이 어느 정도의 예측 정확도와 신뢰도를 가지고 상황 정보에 부합하는지 미지수이다. 따라서 본 논문에서는 기존의 예측 알고리즘과는 다른 접근 방식을 통해, 사용자의 습관이나 행동양식을 데이터베이스로 만들어 이를 고려함으로써 상황인지 시스템의 상황 정보와 부합되는 Flexible Window 기법을 이용한 위치 예측 알고리즘을 제안한다. 제안된 Flexible Window 기법을 이용한 위치 예측 알고리즘은 동일한 실험 조건 아래, Fixed Window 기법을 이용한 위치 예측 알고리즘보다 평균적으로 5.10% 더 우수한 성능을 보인다. 이 방식은 기하급수적으로 늘어나는 상황 정보를 감안했을 때 알고리즘 수행 시 처리 시간의 감소와 예측 정확도를 향상 시킬 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.39-42
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• 2002

The nuclear transmutation technology to Incinerate the long lived radioactive nuclides and produce energy during the incineration process is believed to be one or the best solutions. HYPER(${\underline{HY}}brid {\underline{P}}ower {\underline{E}}xtraction {\underline{R}}$eactor)is the accelerator driven transmutation system which is being developed by KAERI(Korea Atomic Energy Research Institute). Lead-bismuth(Pb-Bi) is adopted as a coolant and spallation target material. In this paper, we performed the thermal-hydraulic analysis of HYPER target using the commercial code FLUENT, and also calculated thermal and mechanical stress of the beam window using the commercial code ANSYS. It is found that there is an optimum value for the window diameter and the maximum allowable beam current can be increased to 17.3 mA for the inner diameter of windows, 40 cm. Finally, the other shapes such as uniform or scanned beam were considered. The results of FLUENT calculations show that the uniform type is preferable to the other shapes of the beam in terms of the window and target cooling and the maximum window temperature is lower than that of the parabolic beam by $58 ^{\circ}C$ for the beam current, 13 mA.

• 한국간담췌외과학회지
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• 제28권2호
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• pp.262-265
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• 2024

The pancreatoduodenectomy (PD) technique is yet to be standardized. One of the most difficult passages in PD is the mobilization of the second, third, and fourth parts of the duodenum. This maneuver is classically performed from the supramesocolic space after the division of the gastrocolic ligament, but traction on the transverse mesocolon and the superior mesenteric pedicle can cause bleeding from the venous and arterial branches of the pancreatic head and uncinate process. We hereby describe a technique to access and mobilize the distal duodenum and proximal jejunum (D2 to J1) through the duodenal window and the Treitz's foramen, performing an almost complete Kocher's maneuver before opening the gastrocolic ligament and mobilizing the hepatic flexure. The anatomical basis and the surgical technique of the duodenal-window-first PD are discussed. The duodenal-window-first approach is a standardizable step of PD that allows an easy and safe mobilization of D2 to J1. This technique has been applied to 15 cases of PD, both open and robotic, with no specific morbidity. Therefore, we propose the adoption of the duodenal-window-first technique as a routine standardized step of PD.

• Journal of Welding and Joining
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• 제33권4호
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• pp.17-23
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• 2015

Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% $CO_2$, Ar-50% $CO_2$, and 100% $CO_2$ shielding gas. Process parameter window was widest with Ar-50% $CO_2$ shielding gas and the penetration was deepest with 100% $CO_2$ shielding gas. The melt dropping was not observed when Ar-50% $CO_2$ or 100% $CO_2$ shielding gas was supplied.

• 한국정밀공학회지
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• 제13권11호
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• pp.143-151
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• 1996

Structural reaction injection molding을 이용한 복합재료의 제품 셩형을 위한 모델링 전략을 설명하였다. 사용된 모델은 두 평행한 원판형 mold에 있는 불 균일한 온도조건의 fiber preform을 통과하는 reactive srsin의 방사형 유동을 시뮬레이션 한다. 이러한 모델은 중요한 작동인자와 공정인자(주입온도, mold의 온도, 유량, cavity의 두께와 섬유의 조밀도)등이 유동속도, 변화(monomer, radical, inhibitor) 및 온도분포 등에 미치는 영향을 예견한다. 열전달과 질량전달 및 화학반응을 고려하여 모델을 개발하였다. 중요한 공정인자를 평가하기 위한 효울적인 공정창( process window)을 제공하는데 본 연구의 목적을 두었다. 2차원적인 Lagrangian 방식에 1차원적인 유동과 제한적인 2차원 열전달을 가정하여 모델을 유도하였고, 방정식은 implicit difference scheme에 의해 전개하였다. 이 모델은 Gonzalez-Romero의 실험 결과와 비교함에 의해 확인되었고, 실험결과가 잘 일치함을 보였다.