• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.967-968
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• 2010

• 폴리머
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• 제34권6호
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• pp.579-587
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• 2010

PET 필름의 물성을 연구하기 위하여 PET의 $T_m$ 보다 높은 다양한 온도에서 압출 후, $18^{\circ}C$로 급냉하였고, 종방향(MD)과 횡방향(TD)으로 각기 다른 연신비 및 다양한 열고정 온도로 제조되었다. 압출 온도, 연신비, 열고정 온도에 따른 PET 필름의 열수축 거동, 밀도, 결정화거동, 열적거동 및 광학적 물성 등의 변화에 대하여 고찰한 결과, MD와 TD 방향의 열수축률은 열처리온도와 압출 온도가 감소함에 따라 증가하였고 연신비가 증가함에 따라 증가하였다. 결정화도와 밀도는 열처리온도와 압출 온도가 증가함에 따라 증가하였고, 융해열(${\Delta}H$)과 예비융점($T_m'$)의 경우 열처리온도와 압출 온도의 증가와 함께 증가하였다. 수평균 분자량과 고유점도는 압출 온도가 증가함에 따라 감소하였고, 인장강도와 탄성률의 경우 연신비가 증가함에 따라 증가하였으나, 열처리온도를 증가하였을 때에는 감소하는 경향을 보였다. 연신 방향과 두께 방향의 굴절률은 연신비와 열처리온도가 증가함에 따라 증가함을 확인하였다.

• 디자인학연구
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• 제19권6호
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• pp.5-8
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• 2006

본 논문은 '거꾸리'라고도 불리는 스트레칭 운동에 이용되는 인버젼 기구의 사용성을 워블메카니즘을 이용하여 효과적으로 개선시킨 가정용 인버젼 기구의 디자인 개발에 관한 것이다. 근래 현대인의 삶에서 건강이 생활의 중심으로 대두되면서 운동을 즐기는 사람들이 늘어났고, 전신 스트레칭이 과다한 업무나 운동의 부작용으로 인한 디스크의 압박 해소에 효과적임이 일반인에게 널리 알려지면서 인버젼 기구의 사용자가 증가하게 되었다. 그러나 기존의 수동 인버젼 기구는 사용자가 테이블의 회전을 위해 무게 중심을 일일이 조정해야 하는 번거로움과 미숙련자들에게는 사용 미숙으로 인해 테이블이 갑자기 회전하는 안전사고 위험 등의 단점이 있었다. 이에 본 연구는 작고 단순한 구조로 큰 감속비를 내며 역전이 방지되는 워블메카니즘을 테이블의 회전 장치와 발목을 고정하는 장치에 도입함으로써 수동 조작 방식에서 자동 방식으로의 개선을 가능하게 하였다. 그 결과, 다양한 신체 조건의 사용자들에게 편리성과 안전성을 높여 주었고, 동력전달 장치 구조의 단순화를 통한 디자인 외부 요소의 단순성을 구현하였다. 이에 가정에서 사용자의 사용이 편리하고 설치 및 보관이 용이한 접이식 가정용 인버젼 기구를 개발하였다.

• 디지털콘텐츠학회 논문지
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• 제14권1호
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• pp.7-14
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• 2013

고사양 디지털 카메라를 내장한 스마트 기기의 보급이 급격하게 증가하면서 고해상도 영상의 품질을 개선하는 기능이 중요해지고 있다. 모바일 기기의 제한된 자원과 영상의 정보량을 감안하면 지나치게 복잡하지 않은 알고리즘을 선택해야 하고 가능한 효율적인 구현 기술을 사용해야 한다. 영상의 질을 향상시키는 기법 중 간단하면서도 널리 사용되는 기술은 명암 값 분포를 조절하는 명암비신장 (contrast stretching) 기법이다. 안드로이드 스마트폰의 경우, 구현 기술로는 가상 머신 위에서 동작하는 자바 라이브러리, JNI (Java Native Interface) 기반 원시 (native) C/C++ 구현 기술, 그리고 SIMD (Single Instruction Multiple Data) 기법이 적용된 NEON 구현 기술 등이 있다. 이 연구에서는 이 세 가지 기술을 선형 명암비신장 연산, 그리고 평활화 명암비신장 연산에 적용하여 그 성능을 실증적으로 비교 분석하였다. 그 결과 원시 C/C++과 NEON 라이브러리의 실행 속도는 자바 라이브러리 실행 속도에 비해 각각 56-78배, 50-76배 빠르다는 점을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1169-1172
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• 2005

For elderly people, an advanced training machine that uses actuator and can adjust load according to muscle activity is proposed. The proposed machine allows users to have a safe and effective training through exercise close to ordinal motion appears in daily life such as stretching or stooping motion. A muscle activity sensor real-timely monitors the activation level of user's muscle during the exercise and the training load is adjusted based on the measured data. The training load is exerted and continuously controlled by electric/pneumatic actuator.

• 한국운동역학회지
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• 제15권2호
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• pp.139-146
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• 2005

We selected six kinds of stretching exercises that can be easily acquired and put to practical use by back pain patients and arranged the practicing order of the exercising method after measuring the % MlVC of the muscle power when a normal person was exercising with a surface EMG. Among the patients complaining of back pain, 20 case groups were given the selected exercise and physical therapy, and 20 control groups were only given a physical therapy. Before and 2 weeks, 4weeks, 6 weeks and 8 weeks after the exercise therapy, a muscle power was measured with a fitness machine and the effectiveness of the exercise was compared. After six weeks difference of the muscle power between the case group and control group was shown, and after 8weeks the case group manifested the stronger muscle power than that of the control group in both male and female. Exercising therapy clearly seems to be helpful in strengthening the muscle power of the back pain patients.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.585-586
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• 2012

• 한국산업보건학회지
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• 제27권2호
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• pp.115-122
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• 2017

Objectives: This study was designed to evaluate the changes in the particle filtration efficiencies of five cloth masks (4 plate types, 1 cup type) with an increasing number of machine washings and the degree of cloth expansion. Methods: NaCl aerosols were generated using an atomizer and passed through cloth masks in a dynamic aerosol chamber. Particle concentrations were measured both before and after for the cloth masks using an optical particle counter (OPC) in the size range of $0.3{\sim}10{\mu}m$. Results: In the original condition, the filtration efficiencies of the five cloth masks were A: 20.1%, B:30.9%, C: 25.0%, D: 26.5%, and E: 40.9%. As the number of washings increased in the order of one, two, and four times, the filtration efficiencies of cloth mask C increased. The filtration efficiency of A, D, and E increased after the first washing. With the exception of B, the filtration efficiency of cloth masks increased after the second washing and those of all cloth masks increased after the fourth washing. This might be caused by the fibers untangling from the yarn and being freed at one end. In this status, the packing density of the textile will not change, but the distances between fibers will increase, which might bring about an increase in filtration efficiency. When the cloth masks were extended by 10% and 20% in one direction, the filtration efficiencies of cloth masks B, D, and E decreased at 10% extension, and those of all cloth masks decreased at 20% extension. When the cloth masks were expanded by 10% and 20% in two directions, the filtration efficiencies of all cloth masks decreased by at least 34.7% at 10% extension, and by at least 60.9% at 20% extension Conclusions: The filtration efficiency of cloth masks could decrease after one to two machine washings, but will increase after four washings in comparison with their original performances. The filtration efficiency of cloth masks will decrease when they are expanded, such as when stretching over the nose during wearing status.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권1호
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• pp.25-44
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• 2010

With the increasing popularity of mobile devices, it has become necessary to protect private information and content in these devices. Face recognition has been favored over conventional passwords or security keys, because it can be easily implemented using a built-in camera, while providing user convenience. However, because mobile devices can be used both indoors and outdoors, there can be many illumination changes, which can reduce the accuracy of face recognition. Therefore, we propose a new face recognition method on a mobile device robust to illumination variations. This research makes the following four original contributions. First, we compared the performance of face recognition with illumination variations on mobile devices for several illumination normalization procedures suitable for mobile devices with low processing power. These include the Retinex filter, histogram equalization and histogram stretching. Second, we compared the performance for global and local methods of face recognition such as PCA (Principal Component Analysis), LNMF (Local Non-negative Matrix Factorization) and LBP (Local Binary Pattern) using an integer-based kernel suitable for mobile devices having low processing power. Third, the characteristics of each method according to the illumination va iations are analyzed. Fourth, we use two matching scores for several methods of illumination normalization, Retinex and histogram stretching, which show the best and $2^{nd}$ best performances, respectively. These are used as the inputs of an SVM (Support Vector Machine) classifier, which can increase the accuracy of face recognition. Experimental results with two databases (data collected by a mobile device and the AR database) showed that the accuracy of face recognition achieved by the proposed method was superior to that of other methods.

• 복식문화연구
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• 제21권6호
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• pp.967-973
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• 2013

During high speed sewing, the needle thread is exposed to dynamic loading, short strike loading, inertia forces, friction, rubbing, force of check spring, bending, pressure, friction, impact, shock and thermal influence. The dynamic thread loading/tension alters throughout the stitch formation cycle and along its passage through the machine. The greatest tensile force occurs at the moment of stitch stretching, when the take up lever pulls for required thread length through the tension regulator. These stresses act on the thread repeatedly and the thread passes 50-80 times through the fabric, the needle eye and the bobbin case mechanism, before getting incorporated into the seam, which result in upto 40% loss in tensile strength of the sewing thread. This damage in the sewing thread adversely affects its processing and functional performance. In this paper, the contribution of dynamic loading, passage through needle and fabric, and bobbin thread interaction in the loss in tensile properties has been studied. It is observed that the loss in tensile properties occurs mainly due to the bobbin thread interaction. Dynamic loading due to the action of take up lever also causes substantial loss in tenacity and breaking elongation of cotton threads.