• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.765-770
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• 2020

The turbochargers used widely in diesel and gasoline engines are effective devices to reduce fuel consumption and emissions. In this study, the isentropic turbine efficiency of the steady flow in a twin-scroll turbocharger for the passenger vehicle gasoline engine was analyzed. The cold gas test bench was designed and made. The pressure and temperature of the inlet and exit of the turbine were measured at 60,000, 70,000, 90,000, and 100,000rpm under the steady-state flow. The isentropic turbine efficiency was calculated. The efficiency was the range of 0.53 to 0.57. The BSR and expansion ratio were changed from 0.71 to 0.84 and from 1.24 to 1.72, respectively. The isentropic turbine efficiency decreased with increasing BSR and expansion ratio. The operation of only scroll A or B was compared with that of the twin-scroll turbine. The isentropic efficiency of using only scroll B was higher than those of only scroll A at 60,000rpm. The isentropic efficiency of using only scroll A was higher than those of only scroll B at 100,000rpm. Therefore, the twin-scroll turbine used in this study is operating effectively in the wide speed range.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.405-406
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• 2023

In the era of AI, intelligent construction safety technologies are being introduced to the construction safety environment, but the application of AI has limitations due to the lack of accident images to learn in complex construction sites. In order to overcome this, we will introduce an intelligent risk detection system that dramatically improves risk detection accuracy by combining AI with digital twin technology, and introduce various cases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.386-391
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• 2021

Turbocharging is becoming a key technology for both diesel and gasoline engines. Regarding gasoline engines, turbocharging can help reduce carbon dioxide (CO2) emissions when used in conjunction with other technologies. This paper presents measurements of the turbine efficiency of pulsating flow in a twin-scroll turbocharger for gasoline engines. A cold gas test bench with a pulse generator was manufactured. The turbine efficiencies were calculated using the measured data of the instantaneous pressure and temperature of the inlet and exit of the turbine. The measurements were carried out at turbine speeds from 60,000 to 100,000 rpm under a pulsating flow of 25.0 Hz and 33.0 Hz. The turbine efficiencies ranged from 0.517 to 0.544. At the pulse frequency, 33.3 Hz, the variations in efficiency were 7.7% and 2.6% at turbine speeds of 60,000 rpm and 100,000 rpm, respectively. The turbine efficiency of the pulsating flow compared to those of steady flow was 7.0% and 3.0% lower at a turbine speed of 60,000 rpm and 100,000 rpm, respectively. The pulsating flow deteriorated the turbine efficiency, but the effects of pulsating flow decreased with increasing turbine speed.

• 한국가스학회:학술대회논문집
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• 2003.05a
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• pp.142-149
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• 2003

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.660-665
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• 2007

This Study is a structure analysis about twin lift telescopic Spreader that usually loading and unloading a container in harbor. Applied load is assumed by lifting 65tons that is the maximum weight of real container. The finite element analysis for 3D model is performed by ABAQUS/Standard. We made an estimate of safety by evaluating the results of the finite element analysis.

• The Research Journal of the Costume Culture
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• v.18 no.6
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• pp.1165-1178
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• 2010

This study is aimed at developing low waist slacks pattern with high satisfaction measurements and beauty for the tween generation girls. For this study, the research method was as follows. By extracting and analyzing industrial and educational slacks pattern, beautiful and motion-suitable slacks pattern will be created. This study presents the ideal slacks pattern that has great fit to tween generation girls by comparing and analyzing the previous 2 slacks pattern studies and the real clothing test. The constructed pattern in the 1st step was modified and adjusted from the best industrial patterns' the location of waist line, waist line gradient, rear waist bottom crotch, hip bottom crotch, dart length, the ease of hip girth, the fitness of rear bottom crotch line which were not well-estimated. The 2nd step was appearance and movement test based on the 1st study. In The 3rd step, the 2nd step was chosen as the final slacks study pattern for its superior appearance & movement satisfaction comparing with other patterns.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.72-72
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• 2011

산업의 발달과 건설재료의 개발 및 설계 시공 기술의 급속한 발전으로 더 가볍고 더 긴 경간을 가진 교량이 건설되고 있다. 그러나 교량이 더 길어지고 가벼워질수록 풍하중에 의한 영향은 더욱 크게 받게 되어 여러 종류의 피해를 입게 된다. 이제는 어느 정도 잘 알려진 1940년에 발생한 Tacoma Narrow교의 붕괴사고는 내풍 설계의 필요성을 극단적으로 보여주는 대표적인 예로서 본격적인 내풍 공학 연구에 시발점이 되었다. 현재까지 아직 시공은 되지 않았으나 기본 설계 및 내풍안정성 평가가 완료되 주경간장 3,300m의 Messina교 및 2,800m의 일본해협횡단도로 프로젝트 초장대 현수교(안)의 출현까지 짧은 기간 동안 비약적인 기술 성장을 이루고 있다. 장대교량의 설계시 많은 풍동실험을 거쳐서 내풍안정성이 뛰어난 단면을 찾게 된다. Akashi교의 경우에도 트러스, 싱글박스, 트윈박스 등의 다양한 단면에 대한 풍동실험을 수행한 끝에 최종적으로 트러스 단면을 선택하였다. Great Belt교에서는 싱글박스 단면을 대상으로 다양한 단부 각도에 대한 결과를 바탕으로 최종 단면을 선정하였다. Stonecutter 교에는 트윈박스를 채용하여 기존 싱글박스를 뛰어넘는 도약을 단행하였다. 그리고 Messina교의 경우에는 약 20년에 걸쳐서 설계를 진행해 오면서 점진적으로 단면을 개선하여 최종적으로 트리플박스 단면을 채택하였다. 국내에서도 광양대교의 설계시 싱글박스에서 시작하여 트윈박스의 간격 최적화를 통하여 최종단면을 도출하였다. Akashi교는 최장경간장을 자랑하지만 고전적인 트러스 단면을 사용함으로써 Great Belt교, Stonecutter교, Messina교 등과 같이 혁신적인 단면을 채택한 교량에 비하여 상대적으로 기술적 가치를 인정받지 못하고 있다. 따라서 새로운 내풍 단면의 개발은 교량 설계를 위한 실용적인 측면에서 매우 중요하다. 본 연구에서는 경제적이고 내풍안정성이 우수한 도전적인 현수교 단면을 개발하는데 목적을 두고 있다. 이를 위하여 먼저 교량 계획 단계에 필요한 자료를 제공하기 위하여 기존 강박스 현수교의 제원을 수집하고 그 특성을 분석하여 각종 구조 변수들이 내풍안정성에 미치는 상대적인 영향을 평가하고, 근사적으로 고유진동수를 추정할 수 있는 추정식을 제시하였다. 그 다음으로 초장대 현수교 단면을 개발하기 위하여 다양한 풍동실험을 수행하고 가능한 단면 형상을 제시하였다.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.330-342
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• 2012

Most of professional baseball teams are not good for business condition because of operation costs in spite of support of mother company. This study measured the relative efficiency and productivity change of the Korean professional baseball teams using DEA model and Malmquist Index for 2006-2008. The main results of this study can be summarized as follows. First, in case of efficiency of CCR for 2006-2008, the number of efficient professional baseball teams(CCR value is one) are two(Doosan Bears, Samsung Lions), two(Doosan Bears, SK Wyberns), two(Lotte Giants, LG Twins) respectively. Second, in case of efficiency of BCC for 2006-2008, the number of efficient professional baseball teams(BCC value is one) are three(Doosan Bears, Samsung Lions, LG Twins ), four(Doosan Bears, SK Wyberns, Samsung Lions, Kia Tigers), four(Lotte Giants, LG Twins, SK Wyberns, Samsung Lions) respectively. Third, average of Malmquist Index representing productivity change for 2006-2008 are 1.0615, 1.0293 respectively. These values mean increase of productivity. Results of this study can be used by inefficient professional baseball teams to improve inefficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.723-729
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• 2019

Turbochargers are an effective device to reduce the fuel consumption. In this study, the mass flow rate of pulsating flow in the twin-scroll turbocharger for the gasoline engine of passenger vehicles was measured. Pulsating flow was achieved using a pulse generator and the mass flow rate of the unsteady pulsating flow was analyzed by comparing it with those of the steady flow. The pulse generator consisted of a rotating upper plate and a fixed lower plate. To measure the mass flow rate of unsteady flow, the orifice flow meter equipped with the difference pressure transducer was used. To analyze the low speed performance of the turbocharger, the measurement was carried out in the speed of turbocharger from 60,000rpm to 100,000rpm. The mass flow parameters of the unsteady pulsating flow showed a large difference compared to those of the steady flow. Those of the unsteady flow showed the hysteresis loop surrounding the mass flow parameters of the steady flow and the maximum variation of the mass flow parameters were 5.0 times those of the steady flow. This phenomenon is the result of the filling and emptying the turbine volute space due to pulsating flow.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.12
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• pp.1689-1699
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• 2007

The purpose of the research was to explore clothing characteristics that tween girls(ages 9-14) consider important when deciding what to wear, as well as what the tween girls' mothers believe that their daughters value. The purposive sample consisted of 41 mother-daughter pairs recruited by $[TC]^2$ (Textile/Clothing Technology Corporation). Subjects were divided into younger(9-11) and older(12-14) normal- and plus-size groups based on Body Mass Index(BMI). There were significant differences between mothers and daughters in rating the importance of seven decision criteria concerning what to wear. The entire tween girls reported that clothes that fit well as the most important criteria in deciding what to wear. Clothes that were comfortable was the only criterion significantly related to the tween girls' body dissatisfaction scores. Mothers rated clothes that are the newest fashion and that friends would be wearing as being significantly more important than their daughters reported. There was a significant negative correlation between tween girls' body dissatisfaction scores and choosing clothes that are comfortable. Normal-size tweeen girls and their mothers differed significantly only when considering the newest fashion and what friends would be wearing. Plus-size tween girls and their mothers differed significantly for four criteria: fit, comfort, best looking, and what friends would be wearing. Both younger and older groups differed with mothers concerning what friends would be wearihng. Additionally, younger girls placed significantly more emphasis than their mothers fit. Older girls did not consider the newest fashion an important a decision criterion, but their mothers believed that they did.