• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.359-362
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• 2009

유체 공급 배관 내에 오리피스를 설치하여, 압력진동의 감쇠효과를 수치해석 및 실험을 통하여 조사하였다. 압력진동이 작다는 가정에 기초하여 오리피스의 음향학적 감쇠 효과를 실험적으로 확인 하였으며, 평균 유동이 있을 경우 관찰되는 감쇠 특성을 수치적으로 조사하였다. 오리피스의 위치에 따른 압력진동의 마디, 즉 속도 진동의 배가 되는 위치에 오리피스를 설치할 때 가장 효과적인 압력 진동이 감쇠 되었다. 배관 내 평균 유속이 있을 경우 공진주파수가 감소하였고, 이에 따라 최적 감쇠 효과를 갖는 오리피의의 위치도 변화함을 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1227-1231
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• 2001

To provide faster service and to relief the road traffic jam, the increase of service speed of conventional railway has been intensively considered. In this study, we measured and analyzed the vibration ride comfort of Saemaeul Train to evaluate the feasibility of 5km/h speed-up in curves and l0km/h speed-up on straight tracks. Four main lines, such as Honam, Kyungboo, ]anghang, Kyungjeon were chosen as representative lines for speed-up feasibility study. The increase of mean ride comfort index in case of speed-up is 0.5-2㏈. The mean ride comfort index of vertical direction in case of speed-up is 107 ∼110 ㏈ for Honam line, 104 ∼112 ㏈ for Kyungboo line, 108∼112 ㏈ for Janghang line and 105∼108 ㏈ for Kyungjeon line. Through this study, we found that the Saemaul Express has slight margin to increase the service speed from the view point of vibration ride comfort.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.250-257
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• 2000

The speed-up of conventional trains is considered as one of the efficient methods to relieve traffic jam and to increase the capacity of transportation. In this study, we measured and analyzed the ride comfort of a push-pull Saemaeul Train with speed-up of 5km/h in curves and 10km/h on straight tracks as compared with present operation speed of the push-pull Saemaeul Trains. Four main lines-Honam, Kyungboo, Janghang, Kyungjeon- were chosen as representative lines for speed-up feasibility study. The increase of mean ride comfort index in case of speed-up is 0.5-2㏈. The mean ride comfort index of vertical direction in case of speed-up is 107-110㏈ for Honam line, 104-112㏈ for Kyungboo line, 108-112㏈ for Janghang line and 105-108㏈ for Kyungjeon line, which are rather high as compared with German trains of similar grade with maximum vehicle speed of 160km/h.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.162-165
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• 2001

In industrial practice, caliber design in shape rolling depends on the designer's experience, which in general is obtained through costly trial-and error process. on-line model which is relations of mean effective strain, roll force and area reduction is derived from finite element process simultion in bar rolling with three rolls.

• 한국안광학회지
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• 제13권1호
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• pp.101-105
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• 2008

목적: 본 연구는 Carl Zeiss사의 Pola Test E-II를 이용하여 성인 대상자의 평균 원거리 입체시를 측정하였으며, 사위 교정에 따른 원거리 입체시의 변화를 평가하였다. 방법: 성인(19~46세) 50명(남 29명, 여 21명)을 대상으로 Pola Test E-II의 D6 Circle 시표와 D8 Line 시표를 이용하여 원거리 입체시를 조사하였다. 결과: 원거리 평균 입체시는 D6 Circle 검사의 경우에 159.6초, D8 Line 검사의 경우에 149.4초를 각각 나타냈다. 사위성분과 사위량에 따른 사위교정 전 후 원거리 입체시의 변화는 D6 Circle 검사의 경우에 외사위는 평균 43.2초 증가하였으며, 내사위는 평균 51초 증가하였다. D8 Line 검사의 경우에 외사위는 평균 42초 증가하였으며, 내사위는 평균 70.2초 증가하였다. 결론: 입체시 검사 결과로부터 내사위인 경우에 외사위인 경우보다 사위교정 후 입체시가 더 크게 향상됨을 알 수 있었다.

• 한국통신학회논문지
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• 제29권8A호
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• pp.950-961
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• 2004

이 논문에서는 최근 무선 통신 환경으로 증가하고 있는 지하철 터널 환경에서의 전파 특성을 측정하고 분석하였다. 측정은 지하철 터널에서 2.45㎓와 5.8㎓의 주파수 대역을 가지고 수행하였다. 측정을 위해 사용된 터널의 길이는 LOS(line of sight: LOS)가 175m이고, NLOS(non line of sight: NLOS)가 270m이다. 지하철 터널은 곡선형이며, 그 단면은 마제형(horseshoe type)이다. 측정 시스템은 협대역 시스템과 광대역 시스템을 이용한다. 협대역 시스템은 경로손실(path loss: PL) 측정을 위해 사용되고 광대역 시스템은 전력지연프로파일(power delay profile: PDP) 측정을 위해 사용된다. 특히, 광대역 시스템은 슬라이딩 코릴레이션 기법을 기반으로 80MHz 칩율과 1023길이의 PN 시퀀스 발생기로 구성하였다. 안테나 빔 형태에 따른 전파특성을 분석하기 위해서 무지향성 안테나와 지향성 안테나를 사용하였다. 경로손실은 터널 환경의 순수한 경로손실만을 나타내었다. 지연 프로파일은 평균초과지연(Mean Exess Delay)와 RMS 지연확산(RMS delay spread)에 대해서 분석하였다.

• Journal of Nutrition and Health
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• 제31권8호
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• pp.1347-1354
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• 1998

The purposes of this study were to : (a) anlayze wating time, service rate, arrival rate, and coustomer expectations/satisfaction in cafeteria business foodservices and (b) identify the differences in those factors between foodservices by menu managmenet systems. The samples were two business foodservices operated by contract management in Seoul. The queue, laptime , service rate, and arrival rate were measured at each foodservice by stopwatch observation. The menu type, delivery system, number of meals served , servide time, and turnover rate of each foodservic was investigated. Questionnaires were developed to survey customer expectations and satisfaction. Satistical data analysis was completed using the SAS package programs for descriptive analysis and t-test. The mean waiting time of island type dafeteria system with separte set -menu was shorter than that of the other. In both foodservices, arrival rates were not significantly different from one another , but sevice rates were significnatly high in dafeteria menu systems. The peak time of the queue was found out at combination set menu line. The separate set menu line had a higher servide rate than the combination set menu line. The mean waiting time of the island type cafeteria line was shorter than that of the straifth type . At the straight type dafeterial line, both arrival rate and service rate were higher than those of island-type. The results of this study suggested that a separate set-menu would be more desirable than a combination set-menu in case of providing set menu with cafeteria menu.

• 대한안전경영과학회지
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• 제5권4호
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• pp.187-194
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• 2003

The purpose of a man-machine chart is improved utilization of a man or a machine. Improved utilization can mean less idle time, rebalanced idle time, or less idle time of an excessive component. In this study we improved the productivity of the assembly line in the electronics company using man-machine chart. The results are applicable for improving the effectiveness of line balancing problems in the electronics industry.

• 한국중재학회지:중재연구
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• 제20권1호
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• pp.67-85
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• 2010

On-line ADR is to use means of settling disputes online to settle disputes happened on-line or off-line. It gave important opportunity for engaging in a commercial transaction to small group or individual. If it uses judiciary proceeding, it will cost too much, complicate and take considerable time. So, because of these reasons, OECD even encourage on-line ADR as a mean for relieving consumer's damage actively on e-commerce. Korea is also trying to introduce on-line ADR partially or completely in Korea Consumer Agency, The National IT Industry Promotion Agency, The Korean Commercial Arbitration Board. However, Korea's on-line ADR is more insufficient than advanced country's. Nevertheless, because on-line needs to introduce, this study suggests the problem and plan centering the type and the present condition of on-line ADR.

• Clinics in Shoulder and Elbow
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• 제19권3호
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• pp.125-129
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• 2016

Background: Superior migration of humeral head has been conventionally determined by measuring the acromiohumeral distance (AHD), We sought to devise a novel measurement system more reliably and accurately than AHD. We described a structural landmark called 'C-line'. In this study, we investigated the clinical usefulness of 'step-off of the C-line (SOC)' compared to that of AHD. Methods: The C-line formed from the medial margin of the proximal humeral head continuing up to the inferior margin of the articular glenoid and then to the lateral border of the scapula. The superior migration of the humeral head triggered by a rotator cuff tear introduces a discontinuity in this C-line. We measured the distance of this discontinuity. We enrolled 144 patients who underwent a rotator cuff repair. We selected 58 controls who didn't have any cuff lesions apparent on magnetic resonance imaging. Using radiographs derived from standardized true anteroposterior views of the shoulder, we measured the SOC and the AHD. We used t-tests for statistical analyses. Results: A rotator cuff tear was associated with an increase in SOC and a decrease in AHD. In control group, the mean SOC was $1.29{\pm}1.71mm$ and AHD was $9.71{\pm}2.65mm$. In cuff tear group, the mean SOC was $3.15{\pm}3.41mm$ and AHD was $8.28{\pm}1.76mm$. The mean SOCs of the patient group in relation to the mean SOC of the control group according to tear size, the SOCs of medium tear and lager groups showed statistically significant increase (p<0.05). Conclusions: The SOC may be a similarly effective to diagnose cuff tears of medium size and larger compared with AHD.