• Steel and Composite Structures
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• 제22권3호
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• pp.663-675
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• 2016

The effects of slenderness ratio, eccentricity and column slope on the load-carrying capacities and failure modes of variable and uniform concrete filled steel tubular (CFST) latticed columns under axial and eccentric compression were investigated and compared in this study. The results clearly show that all the CFST latticed columns with variable cross section exhibit an overall failure, which is similar to that of CFST latticed columns with a uniform cross section. The load-carrying capacity decreases with the increase of the slenderness ratio or the eccentricity. For 2-m specimens with a slenderness ratio of 9, the ultimate load-carrying capacity is increased by 3% and 5% for variable CFST latticed columns with a slope of 1:40 and 1:20 as compared with that of uniform CFST latticed columns, respectively. For the eccentrically compressed variable CFST latticed columns, the strain of the columns at the loading side, as well as the difference in the strain, increases from the bottom to the cap, and a more significant increase in strain is observed in the cross section closer to the column cap.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1325-1331
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• 2007

본 연구에서는 냉방운전 시 가변용량방식의 압축기를 적용한 시스템 에어컨의 냉방능력과 증발기 및 응축기의 온도특성을 조사하기 위해 압축기 운전율(10가지)과 실내외 온도(16가지)의 변화에 따른 시스템의 운전특성을 실험적으로 조사하였다. 시스템의 운전특성은 칼로리미터를 이용하여 측정되었다. 냉방능력은 실외온도가 낮아질수록 실내온도가 증가할수록 더 큰 값을 그리고 압축기 운전율이 증가할수록 냉방능력은 선형적으로 증가하였다. 응축온도는 실외온도 변화에 증발온도는 실내온도 변화에 더 민감하였다. 또한 압력-엔탈피선도를 이용하여 사이클의 운전특성을 분석하였다.

• 품질경영학회지
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• 제36권4호
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• pp.77-86
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• 2008

Due to the rapid growth in automated testing and manufacturing systems, screening inspection becomes very attractive. In this paper, we investigate the effects of limited capacity on screening inspection using a surrogate variable. The model is developed under the assumption that the reprocessed and nonreprocessed items are produced by the same manufacturing process and therefore their quality characteristics are independently and identically distributed. Profit models are constructed which involve four price/cost components; selling price, cost incurred by imperfect quality, reprocessing and quality inspection costs. Methods of finding the optimal screening limits are presented, and a numerical example is given. Sensitivity analyses are also performed to study the effect of a process standard deviation on this model.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.476-481
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• 2009

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurization causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. The O-cell pile load test with variable end plate is operated on second steps - the first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell.

• 대한물리치료과학회지
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• 제25권1호
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• pp.44-51
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• 2018

Background: In this paper, the relationship between the Cranio-Vertebral Angle (CVA) and the vital capacity in each position is reviewed, and the vital capacity in the position is studied. Methods: This study targeted 20 non-smoking female students of U university, which is located in Gyeongju-si. To review the Forward Head Posture (FHP) of each subject, CVA was measured, and FVC, FEV1, and FEF (25-75%) were measured and analyzed using a spirometer. Subjects were ordered to exhale three times with ease and then inhale up to their total lung capacity. After then, they were requested to exhale longer than six seconds. Then the inspiration and expiration were repeated. The measurement was executed in three positions, including supine, prone, and sitting. In each position the measurement was repeated twice, and a one-minute break was given between each cycle, so it was measured six times in total. SPSS 14.0 for Windows was used to analyze the data. The subjects' general properties were analyzed using descriptive statistics, and the correlation between the angle and the respiration variable result in each position was analyzed. The result of the respiration variable in each position was analyzed using the one-way ANOVA, and then a Scheffe post-hoc comparison was executed. Results: According to the analysis result of the correlation between the angle and respiration variable in each position, the sitting position and FEF (25-75%) showed a positive correlation (P<0.05). The respiration variable in each position showed a significant difference in FVC (p<0.05), and the Scheffe post-hoc comparison differed in prone and sitting positions. Conclusion: To increase the FVC of FHP patients, different exercises for each position can be applied, and the result of this study can be utilized as background data for further research.

• Journal of Advanced Marine Engineering and Technology
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• 제34권2호
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• pp.282-288
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• 2010

본 연구는 전자팽창밸브의 개도변화에 따른 가변속 수냉각기의 용량제어 특성에 관한 논문이다. 인버터에 의한 가변속 압축기를 사용한 냉각기를 최적으로 제어하기 위한 선행 연구이며 압축기 회전수별로 제어대상인 전자팽창밸브를 조절하여 증발기 출구의 과열도를 일정한 값으로 제어함으로써 최적의 냉각능력을 얻을 수 있는 과열도 값을 찾는 것을 목표로 하였다. 본 실험의 결과 압축기 회전속도가 일정할 때 팽창 밸브의 개도변화에 따라서 냉각능력이 최대가 되는 지점의 개도량을 실험을 통해서 파악할 수 있었다.

• 한국정보기술학회 영문논문지
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• 제10권2호
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• pp.91-101
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• 2020

Recently, the demand for high penetration of variable renewable energy (VRE) penetration in a power system is increased. In consequence, distribution systems including microgrids confront the increased installation of VRE-based distributed generation. Despite of the high demand of VRE-based distributed generation in a distribution system, the installation of photovoltaic (PV) system in a distribution system has been restricted by various problems. In other words, the hosting capacity for high VRE penetration in a distribution system is limited. This paper analyzes the improvements of hosting capacity VRE penetration of stand-alone microgrid (SAMG) with energy storage system (ESS) by considering virtual-slack (VS) control based on power sensitivity. With the pre-defined power sensitivity, the ESS operates as virtual slack in the SAMG by controlling its bus voltage and phase angle indirectly. Therefore, the ESS enables the increase of VRE penetration in the SAMG. The proposed VS control is realized by analyzing the ESS as a virtual slack in power flow analysis based on power sensitivity. Then its validity is demonstrated with the case study on the SAMG in South Korea with practical data.

• 한국정밀공학회지
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• 제26권5호
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• pp.128-134
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• 2009

This paper aims to design a variable-stiffness type economical safety joint for service robots. The safety joint was designed to have a passive shock absorbing mechanism for protecting human from a catastrophic collision under service condition of robots. A simple mechanism composed of two action disks for switching the load transfer, a spring and a screw for pre-load was proposed. In order to evaluate the performance of the safety joint a testing platform which can carry out the static and impact tests was also designed and fabricated. From the test results, the designed safety joint was proved to have a variable load-carrying capacity and about 42% impact absorption capacity with simple manipulation of the control screw.

• 무역학회지
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• 제41권5호
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• pp.325-351
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• 2016

본 연구는 중국에 진출한 한국기업의 자회사가 보유한 흡수능력의 역할과 진입방식의 역할을 중심으로 지식이전, 네트워크(기업네트워크, 정부네트워크)와 경영성과 사이의 관계를 규명하고자 한다. 본 연구에서 흡수능력은 독립변수, 매개변수, 조절변수로 설정하였다. 또한 진입방식은 단독투자와 합작투자로 구분하여 조절변수로 설정하였다. 실증분석을 위한 자료는 대한무역투자진흥공사 '해외진출 한국기업 디렉토리(2014)'에 수록된 설립일 후 3년 이상 된 기업에서 무작위로 선정하였고, 응답률을 높이기 위해 미리 설문조사에 동의한 중국 자회사를 대상으로 팩스와 이메일로 설문지를 배포한 후 138개 기업으로부터 설문지를 회수하였다. 수집된 자료는 AMOS를 활용하여 공분산구조분석으로 흡수능력과 진입방식의 역할에 대해 규명하였다. 실증분석을 실시한 결과 흡수능력은 네트워크(기업네트워크, 정부네트워크)와 같이 독립변수로서 경영성과에 직접적인 영향을 미치는 것으로 나타났고, 오직 기업네트워크와 경영성과 사이에서 부분적 매개적 역할을 하고 있는 것으로 나타났으며, 외생변수와 경영성과 사이에서의 조절적 역할은 유의한 결과를 보이지 않았다. 또한 한국 기업의 대중국 진입방식의 조절적 역할에 대해서는 정부네트워크 및 흡수능력과 경영성과 사이에서 조절적 역할을 하고 있지만 지식이전과 기업네트워크와 경영성과 사이에서는 통계적으로 유의한 결과를 보이지 않았다. 이와 같은 결과는 해외자회사의 경영성과에 영향을 미치는 변수로서 흡수능력은 매개변수나 조절변수로 취급하기보다는 독립변수로 취급될 필요가 있다는 것을 의미하며, 중국시장에 진출할 때는 단독투자보다는 합작투자가 더 높은 경영성과를 나타내고 있으므로 해외시장 진출의 방법 선택에 있어서 시사점을 제공해주고 있다. 그러나 본 연구는 중국에 진출한 한국기업의 자회사만을 대상으로 하였기 때문에 일반화의 한계가 있다. 따라서 향후에는 여러 국가에 진출한 한국기업의 자회사를 대상으로 연구하는 것이 더욱 바람직하다. 또한 중국 자회사의 경영성과에 영향을 미치는 요인이 매우 다양함에도 불구하고 한정적인 변수를 중심으로 연구가 수행되었기 때문에 일반화의 한계가 있는 것으로 사료된다.

• 한국안전학회지
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• 제21권2호
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• pp.70-79
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• 2006

many plumbing system are needed in the ceiling of the building as it becomes advanced more and more. This leads to make effective space between ceiling level and slab less. Also, piping system is not suitably arranged and operated if it is bent around the columns which they are a lot. But this system can be more effective if it passes through the columns directly. Most people think that those columns should not be damaged with such as holes. But actually this is existed in a hotel building in switzerland. This study is to fing out how much capacity the columns become damaged and low using model size of $20cm{\times}30cm$ rectangular section, and 160cm long, in the structural test. it's compressive strength is focused on $240kg/cm^{2}$ design strength, commonly used in korea. Compressive test for them was done at Hanyang University using UTM one thousand tone(1000t) capacity. Variable numbers for the study are one hole of dia 3cm with distance 20cm or 40cm, two holes of dia 3cm with 20cm and 40cm distance, one hole of dia 5cm with distance 20cm and 40cm, two holes of dia 5cm with 20cm and 40cm distance, me eccentric hole with 20cm and 40cm distance, Normal(without hole). two test specimens of each variable are made for the test. ED5H20 capacity was 16.7% decreased, compared to normal one. While ED5H40 distant 40cm from the end of column top showed 19.5% capacity decrease, compared to normal one. Strain of ED5H20 diameter 5cm, in distance of 20cm form the top of the column was less 5% than the one of diameter 3cm. Finally, conclusions are that in case of hole diameter 3cm, located at 20cm from the end of the column top, capacity was decreased down to 3, percent only compared to the same diameter hole with 20cm distant from the end of it.