• 자원ㆍ환경경제연구
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• 제17권4호
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• pp.813-843
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• 2008

본 논문은 1997년 1월부터 2008년 7월까지의 주별 휘발유가격에 장기적 단기적 가격비대칭성이 존재하는지를 연구한다. 어떤 형태의 가격비대칭이 어느 단계에서 발생하는지 파악하기 위해 생산에서 소비에 이르는 과정을 도매단계와 소매단계로 분리해서 분석한다. TAR와 M-TAR 공적분모형과 거기에 대응하는 비대칭적 오차수정모형에 근거한 분석방법을 이용한다. 도매가격에 있어서는 원유가격 및 환율과 연관된 비대칭성이 두 형태의 오차수정모형에서 장기와 단기에 모두 발견된다. 단기적인 가격비대칭성을 설명하는데는 환율이 원유가격보다 더 중요한 역할을 하는 것으로 나타난다. '로켓과 깃털'에서 예상되는 대폭의 즉각적인 조정과는 달리 원유가격이나 환율의 상승은 도매가격의 인상 후 2주가 되어서야 통계적으로 유의한 주된 영향을 미친다. 그리고 특이하게도 비대칭적으로 원유가격이나 환율의 하락은 같은 기에 도매가격에 통계적으로 유의한 효과를 전혀 미치지 못한다. 소매가격에 있어서는 도매가격과 관련된 비대칭성이 오직 장기에서만 드러난다. 단기적으로는 대칭적으로 가격조정이 이루어진다고 할 수 있다. 도매단계에서 발견된 장기적 비대칭성과는 대조적으로 균형으로부터의 음(-)의 이탈이 양(+)의 이탈보다 장기적 균형 수준을 향해서 더 빠르게 조정되는데 이는 소비자에게는 불리한 현상으로 보인다. 국내 주별 휘발유가격 분석에서 TAR 과정 및 M-TAR 과정으로 나타낸 장기적 가격비대칭이 존재하는 것을 추정된 threshold를 이용해 확언한 것 그리고 장기 및 단기의 가격비대칭을 같은 모형에서 분석한 것은 본 연구가 처음으로 시도했다는 의미를 가진다.

• 한국운동역학회지
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• 제27권4호
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• pp.239-245
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• 2017

Objective: The bobsleigh shoes used in the start section are one of the most important equipment for improving the competition. Despite the importance of the start section, there are no shoes that are specific for bobsleigh athletes in Korea and Korean athletes have to wear sprint spike shoes and practice the start instead of wearing bobsleigh shoes. The objective of the present study was to provide data for improving the performance of Korean bobsleigh athletes by investigating the differences in their split time, plantar pressure, and forefoot bending angle based on skill levels at the start of a run under the same conditions as training conditions. Method: Six Korean bobsleigh athletes were divided into two groups, superior (n=3) and non-superior (n=3). A digital speedometer measured the split time at the start; the Pedar-X system (Novel, Germany) measured plantar pressure. Plantar pressures and split times were measured as the athletes pushed a bobsleigh and sprinted at full speed from the start line to the 10-m mark on the bobsleigh track. An ultra-high-speed camera was used to measure the forefoot bending angle during the start phase. Results: Significant between-group differences were found in split times (p<.000; superior = 2.38 s, non-superior = 2.52 s). The superior group had a larger rearfoot (p<.05) contact area, maximum rearfoot force (p<.01), and a larger change in angles 3 and 4 (p<.05). Conclusion: At the start of a bobsleigh run, proper use of the rearfoot for achieving effective driving force and increasing frictional resistance through a wider frictional force can shorten start time.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1900-1906
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• 2008

신도시 개발 등으로 대도시의 생활권이 확대됨에 따라 수도권 교통의 광역화가 지속적으로 진행되고 있어 대도시권내의 광역교통문제해소 및 혼잡비용 최소화를 위한 체계적이고 지속 가능한 장기 마스터플랜 구상이 필요하게 되었다. 이에 따라, 최근 경기도에서는 동탄 신도시와 서울 강남을 20분대에 연결할 수 있는 대심도 급행전철 사업을 구상하였다. 국토부에서는 경부고속철도 2단계와 호남고속철도 완공에 따른 선로용량 부족해소와 수도권 및 경기 남부 지역 주민들에게 고속철도 서비스제공을 위한 강남권 고속철도 노선(수서${\sim}$동탄${\sim}$평택) 건설이 필요한 것으로 "수도권 철도망 개선방안 연구용역(2007.12)" 결과를 발표하였다. 경기도에서 추진 중인 광역급행전철과 강남권 고속철도 노선이 중복됨에 따라 국토의 이용 효율성 향상과 국가재정의 효율적 투자를 위해 고속철도의 선로 여유용량을 활용한 광역급행전철 혼용에 대한 검토가 필요할 것으로 판단된다. 따라서, 본 연구에서는 고속철도와 광역급행전철을 혼용 운행할 경우 노반분야 및 E & M 기술조건, 중간역 계획, 열차운영계획 등의 분석을 통해 최적화된 혼용운영 방안과 사업비 절감효과 등을 제시함으로써 동일선로에서 이종의 열차가 운행됨에 따른 철도사업의 투자효율성 제고 방안을 제시하고자 한다.

• 전기학회논문지P
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• 제65권4호
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• pp.298-302
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• 2016

Currently, logistics are in small quantities and in diverse forms, and the amounts are continuously increasing. Railway logistics however are losing their market share every year mainly due to low operation speed and loading time, which means the trucks are covering the most of the freights. In order to solve these situations, this paper proposed the high speed freight train as working multi-modality with other modes to make effective transshipment. The high speed freight train has maximum operation speed of 300km/h and electric power to run centralized power supply. There are large dual door system, bogie system covering fluctuating load of 15[ton], automatic loading device, ULD(unit load device) bed and ULD locking system in this freight rolling stock. We calculated the performance of powering and braking capacity for this train and proposed how many vehicles are composed of train set. The results in this paper can help to make a decision to define the technical specification of High-speed freight train for the efficiency of rail freight service.

• Journal of Power Electronics
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• 제4권4호
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• pp.217-227
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• 2004

A robust controller that combines the merits of the feed-back, feed-forward and model-following control for induction motor drives utilizing field orientation control is designed in this paper. The proposed controller is a two-degrees-of­freedom (2DOF) integral plus proportional & rate feedback (I-PD) speed controller combined with a model-following (2DOF I-PD MFC) speed controller. A systematic mathematical procedure is derived to find the parameters of the 2DOF I-PD MFC speed controller according to certain specifications for the drive system. Initially, we start with the I-PD feed­back controller design, then we add the feed-forward controller. These two controllers combine to form the 2DOF I-PD speed controller. To realize high dynamic performance for disturbance rejection and set point tracking characterisitics, a MFC controller is designed and added to the 2DOF I-PD controller. This combination is called a 2DOF I-PD MFC speed controller. We then study the effect of the 2DOF I-PD MFC speed controller on the performance of the drive system under different operating conditions. A computer simulation is also run to demonstrate the effectiveness of the proposed controller. The results verify that the proposed 2DOF I-PD MFC controller is more accurate and more reliable in the presence of load disturbance and motor parameter variations than a 2DOF I-PD controller without a MFC. Also, the proposed controller grants rapid and accurate responses to the reference model, regardless of whether a load disturbance is imposed or the induction machine parameters vary.

• 한국운동역학회지
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• 제17권2호
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• pp.61-73
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• 2007

The purpose of this study was to investigate the influence of the muscular endurance on the kinematic factors during a prolonged run. Subjects, 12 males, who were divided into three groups(lower group, general group, and in higher group) after measuring the lower limb's muscular endurance previously. They were asked toe run on the treadmill at 7.4km/h of speed. To analyze the kinematics parameters of the trunk during running, the ProReflex MCU Camera(Qualisys, Sweden) were used. All parameters were sampled from 5 minute, 40 minute, and 60 minute moments during running. An ANOVA with Repeated Measure was used to test the statistic significance between and within groups for all parameters determined with SPSS 11.0. Significance was defined as p<.05. The conclusions were as follows; There was significantly difference within(lapse of running time) groups in the take-off and minimum knee angle event of swing phase of the trunk flexion and extension. In conclusion, the muscular endurance affected on movement of the trunk during a prolonged run. In addition, it showed that there was significant difference in the energy consumption by lapse of running time. Therefore, it seems to be relationships between the muscular endurance and running efficiency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1066-1071
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• 2007

This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.238-246
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• 2008

This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1166-1171
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• 2008

Through Korean high speed train development project "G7 Leading Technology Development Project" from 1996 to 2002, HSR-350X has been developed. It can run the maximum operating speed of 350 km/h. Based on this technology, KTX-2 which will be served commercially has been developed till 2007. This paper introduces the aerodynamic analysis of the High-Speed EMU and shows the results of optimized aerodynamic nose shape design techniques and clean pantograph panhead original techniques study. These are the important parts of developments for high speed train which maximum speed is 400 km/h. Especially for decrease of tunnel micro pressure waves, the optimized nose area distributions were derived and the characteristics of micro pressure wave were analyzed. The robust optimized pantograph panhead shapes investigated to improve the performance and decrease the vortex flow which is thought to be its noise source. These shapes are clean and robust to external disturbances like unsteady accelerated flow or side wind was derived. Finally aerodynamic performances was verified with PIV and smog visualization by wind tunnel test.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제22권1호
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• pp.15-28
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• 2018

Recently Machine Learning algorithms are widely used to process Big Data in various applications and a lot of these applications are executed in run time. Therefore the speed of Machine Learning algorithms is a critical issue in these applications. However the most of modern iteration Machine Learning algorithms use a successive iteration technique well-known in Numerical Linear Algebra. But this technique has a very low convergence, needs a lot of iterations to get solution of considering problems and therefore a lot of time for processing even on modern multi-core computers and clusters. Tchebychev iteration technique is well-known in Numerical Linear Algebra as an attractive candidate to decrease the number of iterations in Machine Learning iteration algorithms and also to decrease the running time of these algorithms those is very important especially in run time applications. In this paper we consider the usage of Tchebychev iterations for acceleration of well-known K-Means and SVM (Support Vector Machine) clustering algorithms in Machine Leaning. Some examples of usage of our approach on modern multi-core computers under Apache Spark framework will be considered and discussed.