• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.501-503
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• 2006

최근 산업 분야에서 리니어모터는 고속, 고정밀도의 요구사항에 따라 회전 모터와 볼 스크류, 벨트를 이용한 직선구동방식보다 빠르고 정확하며, 효율이 높기 때문에 활발히 이루어지고 있다. 리니어모터 중에서 선형 브러시리스 직류 전동기(LBLDCM)는 다른 리니어모터에 비해 소형, 경량이 가능하고, 저속 및 고속의 운전이 용이하며, 기계 가공 정도보다는 엔코더 등과 같은 위치 결정 응용 분야에 적합하며 본 연구에서 사용된 LBLDCM은 코일 가동형으로 영구 자석에 의해 발생된 자계와 가동자 코일에 흐르는 전류 사이에 작용하는 힘을 이용하게 된다. 이와 같은 LBLDCM을 응용분야에 적용하기 위해서는 구동 중에 속도가 변하는 지점에서 발생하는 진동을 줄여야 하며 목표지점까지의 정확한 위치 제어가 필수적이다. 따라서, 본 연구에서는 다양한 속도 프로파일에 따른 진동에 대해 비교 분석한 후, 이동거리에 따른 적합한 속도 프로파일에 대해 알아보았고, 그 결과를 토대로, 목표지점까지의 위치 오차를 저감하면서 정밀한 위치 제어에 적합한 프로파일을 제시하였다.

• JOURNAL OF ELECTRICAL WORLD
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• s.350
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• pp.94-97
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• 2006

인구11억명의 무한한 시장‘인도’. 특히 인도는 IT 분야에서 세계 최고의 강국으로 부상하고 있다. 거기에 인도는 10여년간 연평균 GDP 성장률 6%대의 고도성장을 이룩하는 등 중국에 이어 경제강국으로의 탈바꿈을 꿈꾸고 있다. 이처럼 매력적인 시장을 기업들은 놓칠리가 없다. 이미 세계 유수의 기업들은 꿈틀대는 인도 시장을 주목해 왔다. 인도에 법인을 설립, 현지의 값싼 노동력을 이용해 가격 경쟁력을 갖추고 시장을 공략하고 있는가하면, 인도시장에 맞는 저가상품을 적극개발, 공급함으로서 시장점유율을 높이고 있다. 국내기업의 경우 자동차와 가점제품의 경우 비교적 성공적으로 정착한 사례로 꼽히고 있다. 현대자동차, LG전자, 삼성전자 등은 인도 현지에서 호평을 받을 정도로 경쟁력을 확보한 상태다. 하지만 전력 시장에서만큼은 아직까지 뚜렷한 성과를 얻어내지 못하고 있다. 가장 큰 이유는 평균 30% 이상에 달하는 관세율을 극복하지 못하고 있기 때문이다. 그리고 인도 수출의 경우 말처럼 쉽지는 않은 상황이다. 인도의 경우 영국의지배를 받던 국가라 아직까지 ABB, 시멘스 등 유럽업계의 강세가 뚜렷해 타 지역국가 업체들의 인지도가 높지 않은 상황이다. 무엇보다“대금이 들어와야 거래가 성사됐다”라고 말을 할 정도로 대금인수에 어려움을 겪는 사례가 부지기수고, 계약 파기도허다해 계약에들인 노력만큼 성공률이 높지 않은 것도 국내 전력 관련업계의 진출 부진의 한이유다. 그렇다고 인도 시장을 그냥 놓치기에는 너무아깝다. 이에 국내업계의 경우 매력적인 시장을 놓치지 않으려 계속해서 인도 시장 진출추진하고 있다. 인도 전력시장 현황을 소개하고, 수출을 위한 국내 업계의 노력 및 수출시 유의해야 할 사항을 종 합적으로 정리해봤다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.996-997
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• 2023

시각 장애인들의 시각 정보에 대한 낮은 접근성은 문화, 예술 활동에 큰 제약을 가져다 주고 있다. 실제로 시각 장애인 중 약 절반 이상이 문화, 여가생활에 만족하지 못한다고 답하였고 전시회, 미술품 감상 또는 관람 활동은 약 5%만이[1] 참여하고 있는 것으로 나타났다. 이러한 한계를 극복하기 위해 시각이라는 감각의 한계를 뛰어넘어 시각 미디어를 즐길 수 있게 하는 서비스를 제작하였고, 이는 크게 웹서비스인 web view editor와 물리적인 촉각 디스플레이로 구성된다. 시각 미디어인 이미지는 8×8로 나눠 각 영역을 OpenCV 라이브러리와 K-means clustering 알고리즘을 이용하여 9 level로 분류시키고, 구분된 level에 맞게 cell의 높낮이 차이를 두기 위하여 Arduino를 통한 회전-선형 변환기를 제작했다. Arduino의 PWM 기능을 이용해 모터의 속도와 방향을 제어하며, 각 모터의 드라이버는 Arduino와 연결되어 있어 모터의 회전을 제어하게 했다. 결과적으로 본 연구에서는 cell의 높낮이 차이를 9 level로 구분하여 시각 정보를 촉각으로 수용할 수 있는 장치를 제작하였고, 이 장치를 통해 기존의 시각 장애인들이 문화 생활을 쉽게 향유하고 이를 바탕으로 창의성과 상상력을 증대시켜 더욱 밀접하게 사회와 연결되고 소통 할 수 있는 기회의 초석이 되기를 기대하는 바이다.

• Journal of Korean Institute of Industrial Engineers
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• v.38 no.2
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• pp.80-88
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• 2012

This paper focuses on small touch key size and spacing that affect the usability of the smart phones. The experiments examined thirty-six different touch key designs, combinations of four touch key sizes (width (mm) ${\times}$height (mm); $4{\times}4$, $4{\times}7$, $7{\times}4$, and $7{\times}7$), and nine spacings (horizontal (mm)${\times}$vertical (mm); $0{\times}0$, $0{\times}1$, $0{\times}3$, $1{\times}0$, $1{\times}1$, $1{\times}3$, $3{\times}0$, $3{\times}1$, and $3{\times}3$). Forty participants volunteered in the experiment. The completion time, error rate, identification discomfort, and control discomfort were measured. The results revealed that the touch key sizes of $7{\times}7$ and $7{\times}4$ provide the best performance in terms of the error rate measure, while the touch key size of $7{\times}7$ provides the best results for other measures. In addition, touch key spacings of $1{\times}1$, $1{\times}3$ and $3{\times}1$ are regarded as the best for all the measures. The results of this study suggest a practical approach for the small touch key design for the smart phones.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.90-97
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• 2008

Wedged insoles are frequently used to reduce the pains caused by the knee arthritis or the foot overuse syndrome. The present study analyzed the effect of wedged rear-foot insoles on the foot pressure in walking. Three medially wedged insoles with three angles (5, 8 and 15") and three laterally wedged insoles with the same angles were made, and a flat insole were prepared. Ten healthy males in twenties walked in a specified line with each insole. Center of pressure (COP), relative vertical force and maximum force on anatomical areas were analyzed from the measured foot pressure data. At heel contact, medially wedged insoles significantly increased the pressure of the medial foot side (COP moved medially by 2-5 mm and maximum pressure of 1st metatarsal head increased by 110-120% relative to the flat insole), In contrast, laterally wedged insoles significantly increased the lateral side pressure (COP moved laterally by 1-5 mm and the ratio of $2^{nd}$ metatarsal head pressure to $1^{st}$ metatarsal head increased by 0.5-2.0 relative to the flat insole). At toe off, both wedged insoles significantly increased the pressure of the medial foot side (COP moved medially by 0.5-10 mm and the ratio of $1^{st}$ metatarsal head pressure to $5^{th}$ metatarsal head increased by 2.0 relative to the flat insole). Especially, the laterally wedged insoles significantly increased the relative vertical force (6-12%) of the rear-foot more than the flat insole.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.42-47
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• 2001

The purpose of this study was to investigate for filtration efficiency of several dust masks, comparing with filtration efficiency certified by KOSHA(Korea Occupational Safety & Health Agency), and to require of the right use of protective respirators. Using a welding fume generator and chamber, several dust masks, which were widely used in the workplaces in korea, were tested for their filtering efficiency for stainless steel arc welding fume. The filtration efficiency testing system consisted of a welding fume generator, a chamber and a filtration unit. The filtration unit was made of a mask which was inserted into the sampling cassette and another sampling cassette, which contained mixed cellulose ester filter paper. These two cassettes were connected with tubing. Stainless steel arc welding fume generator was delivered into an chamber. The welding fume in the chamber was passed into the filtration unit with flow rate of 30 liter/min. The welding fume filtration efficiency was evaluated by gravimetric measurement. Metal concentrations in the welding fume before and after filtration were measured with inductive coupling plasma analyzer. Following results were obtained: Filtration efficiency of welding fume for common hygienic mask was 63.82% and the average efficiencies for A, B, C, D, E, F and G masks were 94.62%, 96.58%, 83.20%, 82.76%, 77.25%, 86.55% and 93.22%, respectively. Our results indicate that dust masks used widely in the welding workplaces in korea are not proper for protecting worker's health and then the use of fume mask should be required.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.201-207
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• 2014

Objectives: Flow rate stability is very important for obtaining reliable measurements. However there is no easily used method for checking whether the flow rate set at the initial stage is sustained during sampling. The purpose of this study was to develop a method to evaluate the flow rate performance of gas sampling pumps with adsorbents commonly used to sample gases. Materials and methods: We tested the back pressure of gas sampling pumps commonly used in Korea with adsorbents such as charcoal and silica tubes and attempted to discover the combination conditions of adsorbents in accordance with back pressure required by ISO standard 13137. Results: We found the combination of sampling adsorbents to be applicable to the pressure drop required by the ISO standard for evaluating flow rate stability under increasing pressure drop and long term (eight-hour) performance. Conclusions: This evaluation method of using a sampling media matrix for checking flow rate stability as proposed by this study could be a highly useful tool for determining the reliability of the performance pumps before sampling.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.108-114
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• 2018

One of the most performed action in daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over $25^{\circ}$, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than $25^{\circ}$ for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on $0^{\circ}$ to $25^{\circ}$ tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.1
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• pp.49-64
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• 2003

Although assembly sequence planning is an essential task in assembly process planning, it is known as one of the most difficult and time consuming jobs because its complexity is increased geometrically when the number of parts in an assembly is increased. The purpose of this study is to develop a more efficient algorithm for generating assembly sequences automatically. By considering subassemblies, a new heuristic method generates a preferred parallel assembly sequence that can be used in robotic assembly systems. A parallel assembly sequence concept provides a new representation scheme for an assembly in which the assembly sequence precedence information is not required. After an user inputs both the directional mating relation information and the mating condition information, an assembly product is divided into subgroups if the product has cut-vertices. Then, a virtual disassembly process is executed to generate alternate parallel assembly sequences with intermediate assembly stability. Through searching parts relations in the virtual disassembly process, stable subassemblies are extracted from translation-free parts along disassembling directions and this extraction continues until no more subassemblies are existed. Also, the arithmetic mean parallelism formula as a preference criterion is adapted to select the best parallel assembly sequence among others. Finally a preferred parallel assembly sequence is converted to an assembly BOM structure. The results from this study can be utilized for developing CAAPP(Computer-Aided Assembly Process Planning) systems as an efficient assembly sequence planning algorithm.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.65-72
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• 2020

Today, the Internet of Things is used in many places, including homes, industrial sites, and hospitals, to give us convenience. Many services generate new value through real-time data collection, storage and analysis as devices are connected to the network. Many of these fields are creating services and applications that utilize sensors and communication functions within IoT devices. However, since everything can be hacked, it causes a huge privacy threat to users who provide data. For example, a variety of sensitive information, such as personal information, lifestyle patters and the existence of diseases, will be leaked if data generated by smarwatches are abused. Development of IoT must be accompanied by the development of security. Recently, Differential Privacy(DP) was adopted to privacy-preserving data processing. So we propose the method that can aggregate health data safely on smartwatch platform, based on DP.