• Journal of Astronomy and Space Sciences
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• 제24권4호
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• pp.417-430
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• 2007

IGS(International GNSS Service) 산출물 생성에 사용되는 지상국의 선정은 산출물 정밀도에 영향을 미칠 수 있는 중요한 과정이다. 지상국 선정에 있어서 지상국 자료의 품질이 좋지 않은 지상국들은 제외시켜야 하며, 전 지구적으로 고른 분포를 갖도록 선정해야 한다. 이 연구에서는 12개의 지상국 망을 이용하여 GPS 위성의 궤도력을 산출하고 지상국 선정이 GPS 위성의 궤도력 산출에 미치는 영향을 분석하였다. 지상국의 성능을 판단하기 위해 자료의 품질을 조사하였으며, 관측개수, 사이클 슬립 개수 및 L1, L2에 대한 의사거리의 다중경로 오차를 고려하였다. 고른 지역분포를 갖는 지상국 선정을 위해서 SOD(Second Order Design) 방법을 사용하여 Taylor-Karman 구조로부터 정의되는 기준 행렬과 여행렬(cofactor matrix)의 차이가 가장 작도록 지상국들을 선정하였다.

• 한국방재학회 논문집
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• 제2권2호
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• pp.105-113
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• 2002

강합성 교량은 자중의 감소, 강성의 증대, 장지간의 적용 등의 재료적 특성에 힘입어 1920년대 이래로 사용되어져 왔다. 그러나 연속교의 경우 내부지점부에서 발생하는 부모멘트로 인하여 콘크리트 부분에 균열이 생기고 콘크리트의 건조수축이나 Creep으로 인한 문제들이 제기 됨에 따라 슬랩앵커를 이용한 부분합성교량이 제기 되었다. 부분합성의 경우 어느 정도의 슬립을 허용하여 이러한 문제를 극복할 수 있다. 본 연구에서는 슬랩앵커의 탄성구간에서의 초기 강성값을 실험을 통하여 알아내고, 단순지지인 경우와 연속교의 경우에 대하여 범용 프로그램을 이용하여 슬래브와 강재를 연결시키는 조인트 요소의 강성값을 변화시켜 전단연결재의 강성값에 따른 합성정도와 내부지점부의 콘크리트 슬래브의 인장응력이 어떤 변화양상을 나타내는지 파악하고자 한다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.515-528
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• 1995

Slips and falls are the major causes of the pedestrian injuries in the industry and the general community throughout the world. With the awareness of these problems, the friction coefficients of the interface between floorings and footwear have been measured for the evaluation of slip resistant properties. During this measurement process, the surface texture has been shown to be substantially effective to the friction mechanism between shoe heels and floor surfaces under various types of walking environment. Roughness, either of the floor surface or shoe heels, provides the necessary drainage spaces. This roughness can be designed into the shoe heel but this is inadequate in some cases, especially a wear. Therefore, it is essential that the proper roughness for the floor surface coverings should be provided. The phenomena that observed at the interface between a sliding elastomer and a rigid contaminated floor surface are very diverse and combined mechanisms. Besides, the real surface geometry is quite complicate and the characteristics of both mating surfaces are continuously changing in the process of running-in so that a finite number of surface parameters can not provide a proper description of the complex and peculiar shoe - floor contact sliding mechanism. It is hypothesised that the interface topography changes are mainly occurred in the shoe heel surfaces, because the general property of the shoe is soft in the face of hardness compared with the floor materials This point can be idealized as sliding of a soft shoe heel over an array of wedge-shaped hard asperities of floor surface. Therefore, it is considered that a modelling for shoe - floor contact sliding mechanism is mainly depended upon the surface topography of the floor counterforce. With the model development, several surface parameters were measured and tested to choose the best describing surface parameters. As the result, the asperity peak density (APD) of the floor surface was developed as one of the best describing parameters to explain the ambiguous shoe - floor interface friction mechanism. It is concluded that the floor surface should be continuously monitored with the suitable surface parameters and kept the proper level of roughness to maintain the footwear slip resistance. This result can be applied to the initial stage of design for the floor coverings.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제2권)
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• pp.143-147
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• 2006

컨테이너의 양 ${\cdot}$ 하역 작업 시 크레인을 정 위치에 고정시키고, 돌풍으로 인해 크레인이 레일방향으로 미끄러지는 것을 방지하는 장치가 레일클램프이다. 쐐기형 레일클램프는 풍속이 증가하면 쐐기작용에 의해 압착력이 증가하므로 구조적으로 안정성과 내구성이 있게 설계해야한다. 따라서 본 연구에서는 순차적 표본방법을 기반으로 하는 크리깅 모델을 이용하여 조 형상최적설계를 수행하였다. 크리깅은 표본점의 반응치를 기초로 내삽법에 의해 임의의 점에서의 반응치를 예측하는 근사기법의 하나이다. 이것은 최적설계 분야에서 자주 사용되는 근사기법인 반응표면법에 비해 반응치의 보다 정확한 예측이 가능하며 특히 비선형성이 강한 함수의 예측에 적합하다고 알려져 있다. 순차적 크리깅 모델에 의하여 구해진 최적해를 상용프로그램을 이용하여 구한 최적해와 비교하고 제안된 방법의 유용성을 검토하였다.

• 보건교육건강증진학회지
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• 제20권3호
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• pp.91-108
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• 2003

Psychological stress is a growing issue in work stress research because work stressors are closely related to depression； and depression, in turn, decreases organizational effectiveness. Considering such causal relationships of work stress, a comprehensive source to control work stress is needed for worksite mental well-being. This study was conducted to identify how social support at work controlled work stress and which characteristics of social support were effective on work stress reduction. The study participants were 240 workers employed in a public hospital in Georgia, U.S.A self-administered survey was given to employees with their pay slips, and followed by a hospital wide voice reminder for 7 days. Surveys were conducted over a 20-day period. The questionnaires asked about job demands, job control, social support at work, depression, job performance, absenteeism, and demographics. The social support construct was structured on the source of support at work and the kinds of support were provided. Statistical analyses were conducted in the structural equation modeling approach. Social support at work was directly related to high job control, low depression, and high job performance. High score of social support at work were significantly associated with high job control, low depressive symptoms, and high job performance. By source of support, only organizational support was positively related to high job control. Organizational support was more effective than supervisor and coworker support. Any stressors and their outcomes were not differenciated by the kinds of support. This result indicated that job control was influenced more by the source of support than the kinds of support provided at work； and the most efficient source of support was the organization. Organizational support was a strong factor in improving workers" perceived controllability of their jobs from a work stress reduction perspective.tive.

• 전자공학회논문지SC
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• 제48권6호
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• pp.82-90
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• 2011

본 논문에서는 실외 정밀 위치 추정을 위하여 설계된 GPS(Global positioning system)-INS(Inertial navigation system) 결합 시스템의 잡음 필터링 기법과 데이터 결합을 위한 기법을 소개한다. 실외 이동 항체의 속도 변화에 따라 차등적으로 발생하는 INS의 잡음들을 이산 웨이블릿 변환을 통해 신호를 분석하고 발생하는 잡음들을 데이터의 왜곡을 최소화하며 제거할 수 있는 차등 임계화 기법을 통한 필터링 기법을 제안하였다. 이는 항체의 가/감/등속을 고려하지 않고 특정 로우/하이 필터를 적용하여 데이터의 왜곡이 일어나는 기존 필터링 기법을 개선한 것이다. 또한 UPF를 이용해 비선형 특성과, 비가우시안 잡음의 특성을 가지는 실외 이동 항체의 GPS와 INS의 결합시킴으로서 실외에서 정밀하게 위치를 추정할 수 있게 하였고 이를 설계하여 실험을 통해 성능을 분석하였다.

• 한국의상디자인학회지
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• 제16권1호
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• pp.41-52
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• 2014

The purposes of this study were to explore differences in utilization of information sources depending on the length of buyers' career and annual sales volume of stores where buyers work for. The questionnaire was prepared by the researcher and was answered by 200 buyers who purchase their items from Dondaemun market. The researcher analyzed the data using both ANOVA and Tukey's test as a post-hoc test. The conclusion of this study is summarized below. First, there were significant differences in utilization of information sources among buyer groups depending on the length of buyers' career. The buyers with more than 10 years career showed more effective utilization of information source such as resident buying offices, manufacturers, trade publications, trade associations, fashion reports, celebrities, window shopping, professional magazines, and advice from others. Second, there were significant differences in utilization of information sources among buyer groups depending on annual sales volume of the stores where the buyers work for. The buyer who work for the store with its annual sales volume in excess of 2 billion won showed more effective utilization of information source such as trade association, professional magazines, sales record, want slips, advertising results, sales trends, customer surveys, sales meetings, customer advisory panel, in-store merchandising bureau and advice from other experienced buyers. However, buyers of the store with its annual sales volume lower than 100 million won showed different pattern utilization of information sources such as vendors, trade publication, celebrities and advice from others.

• 한국기계가공학회지
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• 제19권8호
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• pp.28-34
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• 2020

In this study, hole-boss locking washers were developed to prevent vibrational loosening, and a benchmark test was conducted to compare these washers with existing wedge locking washers, which are imported and high-priced. The developed washers consist of an upper washer with bosses and a lower washer with holes, and the bosses are caught in the holes so that the bolt is not loosened. Additionally, the top side of the upper washer and the underside of the lower washer have small wedges perpendicular to the direction of the bolt loosening, suppressing slips. A test by the Korea Test Laboratory indicated that the ratio of the loosening torque to the joining torque is greater than 70%, confirming that the developed washers have a sufficiently high anti-loosening performance. A Junker test apparatus was manufactured for the testing of vibrational loosening and a test comparison between the proposed washers and the existing wedge locking washers shows that the proposed washers have a slower reduction in the clamping force and a higher loosening-resistance in a vibrational circumstance compared with the wedge locking washers. These results indicate that the developed washers demonstrate a high performance and boast price competitiveness.

• 한국운동역학회지
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• 제23권4호
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• pp.377-385
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• 2013

Fall is very fatal accident causes death to older people. Shoe may affect to fall. Shoe influences risk of slips, trips, and falls by altering somatosensory feedback to the foot. The purpose of this study was to investigate the analysis of non-slip shoes for older people and influence on older people's lower extremity. For this study twenty three healthy older people were recruited. Each subjects walked over slippery surfaces (COF 0.08). Four pairs of non-slip shoes (shoe A had the greatest COF, 0.23 while shoe B, C, and D had smaller COF relatively) for older people were selected and tested mechanical and biomechanical experiment. For data collection motion capture and ground reaction forces were synchronized. There were statistically significant differences for slip-displacement, coefficient of friction, braking force, propulsion force, knee range of motion and knee joint stiffness by shoes. It was concluded that shoe A was the best for non-slip function because of the lowest slip displacement, the highest braking and propulsion forces, and the highest mechanical and biomechanical coefficient of friction where as shoe B, C, D were identified as a negative effect on the knee joint than shoe A. To prevent fall and slip, older people have to take a appropriate non-slip shoes such as shoe A.

• 한국지반공학회지:지반
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• 제12권2호
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• pp.19-32
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• 1996

시간영역의 지진 가속도-시간 이력을 주파수 영역의 courier 진폭-주파수 이력으로 변화시키는 Trifunac의 경험적 모델을 기초로 하여 지진 관측소에서 측정된 임의 규모의 실제 지진기록들을 필요한 규모의 지진기록으로 유사화시키는 지진 확대 (scaling) 기법을 제안하였다. 또한, 지진 규모(M) 5.6의 지진기록을 이용하여 지진 규모(M) 8.0의 유사지진을 작성하여 동적 재하 시험 장치에 적용가능하도록 하였다. 지진 확대 (scaling) 기법은 MMI(modified mercalli intensity), 지진기록 부지의 조건,진앙거리,지진 가속도 성분의 방향, 해석의 신뢰도 등을 고려할 수 있으며, 다양한 지진 기록들에 적용가능하였다.유사지진은 수평방향의 성분들만을 고려하여 작성되었다. 압력토조내에 설치된 모형인장말뚝과 개단압출말뚝에 대한 유사지진 진동에 의한 동적 말뚝재하시험이 가능하였다. 정적 말뚝재하시험시 인장말뚝과 압축말뚝의 거동은 매우 상이하였는데, 인장말뚝은 2~3회의 급작스런 미끄러짐 변위를 수반하였다. 또한, 유사 지진 진동중 인장말뚝과 개단압축말뚝의 거동특성은 매우 상이하였으며, 지지력 감소특성도 크게 달랐다.