• 방송공학회논문지
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• 제26권2호
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• pp.132-142
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• 2021

본 연구는 실생활에서 가장 많이 접할 수 있는 모바일 전면 카메라를 이용하여 심장박동, 심장박동 변이율, 산소포화도, 호흡도, 스트레스수치, 혈압을 측정할 수 있는 효과적인 방법론을 제시하는 것이 목적이다. Blaze Face를 이용하여 실시간으로 얼굴인식을 진행하여 안면 이미지 데이터를 취득하고 눈, 코 입, 귀의 특징 점을 이용하여 이마를 관심영역으로 지정하며 평균값을 시간 축으로 정렬한 후 생체징후 측정에 이용하였다. 생체징후 측정 기법은 fourier transform을 기본으로 이용하였으며, 측정하고자 하는 생체징후에 맞게 노이즈 제거 및 필터 처리함으로써 측정값의 정확도를 향상 시켰다. 결과를 검증하기 위해 접촉식 센서와 비접촉식 센서 비교를 진행하였다. 분석 결과 안면 이미지를 이용하여 심장박동, 심장 박동 변이율, 산소포화도, 호흡도, 스트레스, 혈압 총 여섯 가지 생체 징후를 추출 할 수 있는 가능성을 확인하였다.

• 전기학회논문지P
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• 제65권2호
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• pp.130-135
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• 2016

Gait recognition has advantage of non-contact type recognition. But It has disadvantage of low recognition rate when the pedestrian silhouette is changed due to bag or coat. In this paper, we proposed new method using combination of gait energy image feature and thermal face image feature. First, we extracted a face image which has optimal focusing value using human body rate and Tenengrad algorithm. Second step, we extracted features from gait energy image and thermal face image using linear discriminant analysis. Third, calculate euclidean distance between train data and test data, and optimize weights using genetic algorithm. Finally, we compute classification using nearest neighbor classification algorithm. So the proposed method shows a better result than the conventional method.

• 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.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1127-1132
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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.

• 한국산업정보학회논문지
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• 제20권2호
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• pp.57-63
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• 2015

얼굴 표정인식 기술은 다른 감정인식기술에 비해 비접촉성, 비강제성, 편리성의 특징을 가지고 있다. 비전 기술을 심리로봇에 적용하기 위해서는 표정인식을 하기 전 단계에서 얼굴 영역을 정확하고 빠르게 추출할 수 있어야 한다. 본 논문에서는 성능이 향상된 얼굴영역 검출을 위해서 먼저 영상에서 YCbCr 피부색 색상 정보를 이용하여 배경을 제거하고 상태 기반 방법인 Haar-like Feature 방법을 이용하였다. 입력영상에 대하여 배경을 제거함으로써 처리속도가 향상된, 배경에 강건한 얼굴검출 결과를 얻을 수 있었다.

• 한국비블리아학회지
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• 제32권4호
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• pp.161-188
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• 2021

WHO에서 팬데믹을 선포하면서 다중이용시설인 도서관 역시 여러 변화를 맞이하고 있다. 전 세계적으로 각국의 국립도서관을 비롯한 대다수의 도서관이 휴관을 발표하였으며, 기존에 대면하여 제공하던 서비스를 대부분 비대면 서비스로 전환하였다. 하지만 그 서비스의 범위가 지자체 및 도서관별로 상이하여 사서의 소신있는 대응이 어렵고, 이용자 역시 불편을 겪고 있다. 따라서 본 연구에서는 도서관 비대면 서비스의 범위를 파악하고, 이에 대한 이용자의 인식조사를 통해 팬데믹 상황에서 도서관 비대면 서비스 운영 방향을 제안하고자 하였다. 이를 위해 37개의 공공도서관에 도서관 이용자를 대상으로 2020년 2월 12일부터 약 3주간 온라인 설문조사를 진행하였으며, 회수된 117부의 응답지를 SPSS 통계 프로그램을 활용하여 빈도분석, 회귀분석, 상관분석, 신뢰도 분석 등을 실시하였다. 설문결과 및 자료조사 결과를 통해 도서관 비대면 서비스 운영 방향으로 도서관 서비스 재정립, 도서관 비대면 서비스 확대, 이용자 교육 진행, 비대면 서비스에 대한 홍보 진행, 이용자 의견 수렴을 제안하였다.

• 소성∙가공
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• 제17권4호
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• pp.278-283
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• 2008

This paper concerns the die face design for a heat protect panel aided by the finite element forming analysis in order to eliminate the surface defect and to improve the surface quality. The CAE procedure of the stamping process is introduced in order to reveal the reason of surface inferiorities and to improve surface quality. Complicated shape of the product induces the surface inferiorities such as wrinkling due to the insufficient restraining force of the forming blank and the non-uniform contact of the blank with the tools. This paper proposes a new guideline for the die design which includes the modification of tool shapes and addition of the draw-beads on the tool surface for ensuring the increased the restraining force with the uniform contact condition. The effectiveness of the proposed design is verified by the forming analysis and is confirmed by the tryout operation in the press shop. The analysis and test results show that the modified process parameters such as tool shapes and draw-beads can reduce the tendency of wrinkling and improve surface quality.

• 대한기계학회논문집A
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• 제22권2호
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• pp.476-481
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• 1998

It is generally known that in high speed work with more than 1000 m/min cutting speed, according to the work material phenomenon of tool wearing is increased due to the some produced neat and as a result this makes the cutting work impossible. In this study, the high speed cutting is possible because of the different cutting from the presently known fact. That is, most of generated heats influence on the quantity flowing in chip greatly. Therfore, this study aims at the behavior of cutting heat generated at high speed cutting. It makes clearly the euqntity of heat flowing in chip, work materal, tool, and inflowing ratio. The cutting mechanism varies by the changing of cutting depth, slant face and contact area through this study. And it is exammined that the influence of heat of all parts is greatly due to the change the contact length of clearance face. It is confirmed from the exp[eriment that the inflowing heat ratio influences the cutting speed greatly and the heat of clearance face can not be disregarded.

• Steel and Composite Structures
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• 제26권6호
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• pp.771-791
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• 2018

This paper deals with the low velocity impact response and dynamic stresses of composite sandwich truncated conical shells (STCS) with compressible or incompressible core. Impacts are assumed to occur normally over the top face-sheet and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The displacement fields of core and face sheets are considered by higher order and first order shear deformation theory (FSDT), respectively. Considering continuity boundary conditions between the layers, the motion equations are derived based on Hamilton's principal incorporating the curvature, in-plane stress of the core and the structural damping effects based on Kelvin-Voigt model. In order to obtain the contact force, the displacement histories and the dynamic stresses, the differential quadrature method (DQM) is used. The effects of different parameters such as number of the layers of the face sheets, boundary conditions, semi vertex angle of the cone, impact velocity of impactor, trapezoidal shape and in-plane stresses of the core are examined on the low velocity impact response of STCS. Comparison of the present results with those reported by other researchers, confirms the accuracy of the present method. Numerical results show that increasing the impact velocity of the impactor yields to increases in the maximum contact force and deflection, while the contact duration is decreased. In addition, the normal stresses induced in top layer are higher than bottom layer since the top layer is subjected to impact load. Furthermore, with considering structural damping, the contact force and dynamic deflection decrees.

• KDI Journal of Economic Policy
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• 제43권2호
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• pp.103-123
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• 2021

This paper examines the impact of the regional cash subsidies which were granted in some districts in addition to the national universal stimulus payment in South Korea related to the COVID-19 pandemic. We evaluate the effects of the cash distribution per resident on aggregate credit and debit card sales and sales by industry using the difference-in-difference method. The increment in card spending due to the cash subsidy is about 1.58%p in total, and this effect is concentrated within a single month. The consumption stimulating effect is prominent among (semi)-durable goods that do not require close interactions between customers and sellers. In contrast, the effect is relatively small in the high-contact face-to-face service sectors and restaurants, areas the COVID-19 pandemic hit directly. On the other hand, some service sectors where customers could wear face masks, such as education and fitness, experienced a substantial sales boost due to the cash subsidy.