• 대한한의진단학회지
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• 제17권3호
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• pp.225-232
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• 2013

Objectives The aim of this study is to design a part in contact with the face of computerized tongue diagnosis system (CTDS), so that external light is effectively shielded even if the facial appearance and degree of protrusion differ when a patient opens or closes his/her jaws. Methods Each of the 4 researchers manually produced clay models of the part in contact with the face of CTDS. Shielding and contact feeling of the clay models were evaluated by 20 assessors. Based on the evaluation, we selected the appropriate model and produced the final silicon model. Then we evaluated the performance of the shielding of the completed silicon model. We took tongue pictures of 60 participants with a CTDS applying the silicon model in condition with external light and without it. The color values in RGB color model and gray scale of the tongue pictures in condition with external light were compared with those without external light. Results There was no significant difference between the color values of the picture taken in condition with external light and those without external light. Conclusions We concluded that the produced part in contact with the face of CTDS can effectively block out the external light.

• 대한금속재료학회지
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• 제48권5호
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• pp.456-461
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• 2010

We investigated the In-based ohmic contacts on Nitrogen-face (N-face) n-type GaN, as well as Ga-face n-type GaN, for InGaN-based vertical Light Emitting Diodes (LEDs). For this purpose, we fabricated Circular Transfer Length Method (CTLM) patterns on the N-face n-GaN that were prepared by using a laser-lift off method, as well as on the Ga-face n-GaN that were prepared by using a dry etching method. Then, In/transparent conducting oxide (TCO) and In/TiW schemes were deposited on the CTLM in order for low resistance ohmic contacts to form. The In/TCO scheme on the Ga-face n-GaN showed high specific contact resistance, while the minimum specific contact resistance was only 3${\times}$10$^{-2}$ $\Omega$-cm$^{2}$ after annealing at 300${^{\circ}C}$, which can be attributed to the high sheet resistance of the TCO layer. In contrast, the In/TiW scheme on the Ga-face n-GaN produced low specific contact resistance of 2.1${\times}$10$^{5}$ $\Omega$-cm$^{2}$ after annealing at 500${^{\circ}C}$ for 1 min. In addition, the In/TiW scheme on the N-face n-GaN also resulted in a low specific contact resistance of 2.2${\times}$10$^{-4}$ $\Omega$-cm$^{2}$ after annealing at 300${^{\circ}C}$. These results suggest that both the Ga-face n-GaN and N-face n-GaN.

• 소성∙가공
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• 제29권3호
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• pp.144-150
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• 2020

In this paper, we propose the generation of a double enveloping worm thread profile with a non-developable ruled surface. Thread surface machining cuts all the way from the tip to the tooth root at one time, like full-face contact machining, rather than cutting several times like point machining. This cutting can reduce the cutting duration and achieve the smooth surface that does not require a grinding process for the threaded surface. The mathematical model of the cutting process was developed from theoretical equations, and the tooth surface was generated using two parameters and modeled in the CATIA using the generated Excel data. Additionally, the machining process of the worm was simulated in a numerical control simulation system. To verify the validity of the proposed method, the deviation between the modeling and the workpiece was measured using a 3D measuring machine.

• 한국정밀공학회지
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• 제22권6호
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• pp.159-167
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• 2005

This work focuses on the effects of crack free friction on Mode II stress intensity factors, $K_{II}$, for a vertical surface crack in a two-dimensional finite element model of TiN/steel subject to rolling contact. Results indicate that maximum $K_{II}$ values, which occur when the load is adjacent to the crack, may be significantly reduced in the presence of crack face friction. The reduction is more significant for thick coatings than for thin. Crack extension and increased layer thickness result in increased $K_{II}$ values. The effect of crack face friction on compressive $K_I$ values appears negligible. Comparative results are presented for $MoS_2/steel$ and diamond-like carbon(DLC)/Ti systems.

• 한국교육논총
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• 제43권1호
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• pp.1-27
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• 2022

세계적으로 코로나19 바이러스가 만연해짐에 따라 다양한 분야에서 비대면화를 시행하게 되었고, 교육 시스템 또한 급격한 비대면화로 인해 많은 관심이 집중되기 시작하였다. 본 연구의 목적은 현재까지 계속적으로 변화하고 있는 교육환경에 맞추어 비대면 교육이 나아가야 하는 방향성에 대해서 분석하는 것이다. 본 연구에서는 다양한 의견들이 존재하는 소셜네트워크 빅데이터를 수집하기 위하여 텍스톰(Textom), 유씨넷6(Ucinet6) 분석 도구 프로그램을 사용하여 데이터를 시각화하였다. 연구 결과 '코로나'와 관련된 키워드가 주를 이루었으며 '기사', '뉴스'등의 높은 빈도의 키워드들이 존재했다. 분석 결과 네트워크 장애 및 보안 문제와 같은 비대면 교육에 관련한 다양한 이슈들을 확인해 볼 수 있었고, 분석 이후 교육 시장의 성장과 교육 환경의 변화에 따른 비대면 교육 시스템의 방향성에 관하여 연구하였다. 또한 빅데이터를 이용하여 분석한 비대면 교육시의 보안 강화 필요성과 수업 방식에 대한 피드백의 필요성이 존재한다.

• 융합보안논문지
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• 제22권1호
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• pp.29-38
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• 2022

감염 질병의 심각한 확산으로 인해 방역의 중요성이 점점 커지고 있다. 또한 방역 이슈가 없는 언택트 산업에 대한 관심도 늘어나고 있다. 본 논문에서는 등록된 사용자의 얼굴을 인식함으로써 비접촉 방식으로 출입을 통제하는 비용 효율적인 라즈베리파이 기반 도어락 시스템을 설계하고 개발한다. 우선, OpenCV의 Haar-based cascade를 사용하여 매우 단순한 특징들을 조합하여 객체를 찾고, 얼굴 인식을 진행한다. 그리고 LBPH (Local Binary Pattern Histogram)을 사용하여 이미지의 질감을 이진화하여 특징을 찾아낸다. 라즈베리파이 3B+ 보드, 초음파 센서, 카메라 모듈, 모터 등으로 언택트 도어락 하드웨어를 구현하고, 얼굴 인식 및 매칭 알고리즘을 포함한 소프트웨어를 기반으로 약 500장의 이미지 데이터를 학습시켜 실험한 결과, 최대 85.7%의 인식률을 보이며 사용자를 구분하는 성능을 검증할 수 있었다. 또한, Haar-cascade 알고리즘 성능의 광원에 대한 영향성을 파악하여 그 개선 가능성을 살펴보았다.

• Tribology and Lubricants
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• 제21권5호
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• pp.201-208
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• 2005

This paper presents the FEM analysis on the contact behavior characteristics of mechanical face seals in a small hydro-power turbine. Especially, the axial displacement and contact normal stress between a seal ring and a seal seat of a primary sealing unit have been analyzed as functions of rotating speed of a hydro-turbine, sealing gap, water and cooling fluid temperature. Those are strongly related to a leakage of water and wear between a seal ring and a seal seat. The FEM computed results present that the rotating speed of a hydro-turbine may be kept less than 800 rpm, and the sealing gap in a primary sealing unit is restricted $0.5\~5$. The coolant temperature in which is most influential parameter to the contact behaviors of a sealing unit may be kept less than $15^{\circ}C$ for a safe operation of a sealing unit without a leakage and wear.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.32-38
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• 2006

During stereolithography processes, the shape errors such as curl distortion and distortion of side face are generated due to the shrinkage of liquid resins. In this study, the effects of dimension of part and structure of supports on the shape error are examined. Cubic specimens which have different thicknesses are manufactured and their deformations are measured with CMM. Thicker part generates smaller curl distortion of top face and larger of bottom face. Also thicker part generates larger distortion of side face until part thickness increases to about 20mm. Larger stiffness of supports which is obtained by shorter spacing of the supports and line type contact instead of point type contact generates smaller shape error of the part.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.20-31
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• 2021

COVID-19로 인한 비대면 문화의 확산은 언택트 서비스 혁신과 화상회의 플랫폼을 통한 비대면 커뮤니케이션 확대로 이어졌다. 그러나 실시간 온라인 커뮤니케이션에서는 비언어적 표현을 확인하는 것이 어려워졌고, 특히나 눈 맞춤을 통한 상호작용은 불가능한 상황이다. 감정을 공유하고 친밀감을 쌓는데 도움을 주는 등 눈 맞춤의 긍정적인 효과가 있음에도 불구하고 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 실증적으로 검증한 연구는 전무한 실정이다. 이에 이 연구는 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 검증하고자 하였다. 커뮤니케이션의 맥락과 눈 맞춤 유무에 따라 6가지 영상 처치물을 사용하여 지속 사용 의도, 성과 기대, 상호작용성, 개인적 유대감을 측정하였다. 연구결과, 모든 맥락에서 눈 맞춤이 없을 때보다 눈 맞춤이 있을 때 모든 측정 변인에서 높게 평가되었다. 이 연구는 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 실험을 통해 검증하고 기술의 필요성과 발전 방향을 제안하여 실시간 온라인 커뮤니케이션에서 더 나은 사용자 경험을 제공하는데 기여할 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.870-874
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• 2007

Golf ball spin rate after impact with club is created by the contact force, which is greatly influenced by ball and club mass, material, impact speed, and club loft angle. Previous studies showed that the contact force is determined as the resultant force of the reaction forces normal and tangential to the club face at the contact point. The normal force causes the compression and restitution of the ball, and the tangential force creates the spin. Especially, the tangential force takes either positive or negative values as the ball rolls and slides along the club face during impact. Although the positive and negative tangential forces are known to create and reduce the back spin rate, respectively, the mechanism of ball spin creation has not yet been discussed in detail. It is shown in this work that the linear impulse of the tangential force is directly related to generation of back spin rate of golf ball. The linear impulse can be calculated from the tangential force, which depends upon many factors such as ball and club mass, material, impact speed, and club loft angle. In this research, the influence of the contact force between golf club and ball is investigated to analyze the mechanism of impact. For this purpose, the contact force and the contact time at impact between golf club head and ball are computed using FEM.