• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.521-527
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• 2003

Modern automatic transmissions equip torque converters with lock-up clutches to reduce the energy loss of hydraulic systems. Instead of simply engaging the clutch disks, the new technology of clutch slip has been developed to improve the overall efficiency of power transmission. There are two major problems with the clutch slip system. The first is how to keep the slip between the two disks within a small range and the second is when to start or stop the slip. In this paper, the second problem is discussed in view of the vehicle economy. With a simple vehicle dynamic model, the fuel economy is calculated to determine the lock-up strategy. Then the lock-up strategy is developed for a slip schedule.

• 음성과학
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• 제8권2호
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• pp.7-22
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• 2001

This research with 40 hearing impaired children was performed to find out the characteristics of the phonological processes for each age, hearing loss degree and aided threshold degree through the transcriptions. The phonological processes of hearing impaired children are similar to those of normal children with a peculiar type of patterns in phonological processes. The results show that: (1) Between 5 and 6 year old groups the phonological processes were significantly different in palatal backing, glottal replacement and frication; between 6 and 7 year old groups the phonological processes were significantly different in velar fronting, labialization, alveolization and labial assimilation; between 7 and 8 year old groups the phonological processes, labialization, alveolization and alveolar assimilation, however 8 year old group showed more phonological processes than 7 year old group. (2) Between moderately-severe and severe hearing impaired groups, phonological processes were significantly different in the omissions of postvocalic, nasal and velar, stopping and stop assimilation. The differences of severe and profound groups were not found at all. (3) Aided hearing thresholds did not show any significant difference.

• International Journal of Contents
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• 제10권2호
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• pp.37-41
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• 2014

This study defined the pre-elderly as middle age people from 50 to 59. Because it is difficult to produce a design to satisfy the pre-elderly without deeply understanding them, their financial and physical characteristics and persona-based scenario method was studied. An experimental study about persona based scenario method was conducted, and as a result, the types of personas found were as follows: 1) Users enjoy the same games online and offline. 2) Users enjoy playing alone on the computer. 3) Users prefer games that end quickly with win or loss. Writing the situation scenario for each type, the pre-elderly's problems and needs occurring while they play web board games were obtained. The obtained user requests were as follows: users would like the level of difficulty to be simpler in the game of baduk; users wanted unlimited credit and refrainment from using English words in go-Stop; and there were simple comments about game screen design.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.408-413
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• 2002

From the moment that electricity is applied to a relay, a wheel turned, or a valve opened, the process leading to the need for maintenance begins, The uninitiated will tell you that the Maintenance man is someone who repairs something when it has gone wrong. Unfortunately, in any large engineering concern, such as a railway, it is not possible to work on the principle that only when something breaks down should it get any attention. The failure of one contact, diode or bearing could well stop not only the assembly of which it is a part, but the flow line or process, with loss of revenue, and clientele, and often with effects on the safety of both staff and the traveling public. So, we have to establish the reliable and cost-effective maintenance system to resolve these problems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.258-259
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• 2007

In this paper, the secant method is adopted to improve a transfer function required by specific filtration properties. It is advantageous over the conventional and widely used 'Template method' in that it enables users to seek the position of a pole which will turn out to meet well the requirements of in-band insertion loss as well as stop-band rejection even after a small number of iterative steps. For validating the proposed method, the transfer function of a 4-pole waveguide filter is targeted.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1132-1136
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• 2014

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.815-829
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• 2008

Debris flows are a natural hazard which looks like a combination of flood, land and rock slide. Large rainfall in July 2006 produced several large scale debris flows and many small debris flows that resulted in loss of life and considerable property and railway damage, as was widely reported in the national media. The hazard "debris flow" is still insufficiently researched. Furthermore debris flows are very hard to predict. Flexible Ring net barriers are multi-functional mitigation devices commonly applied to rock fall or floating wood protection in floods, snow avalanches and also mud flows or granular debris flows, if properly dimensioned for the process or processes for which they are intended. Overtopping of the barriers by debris flows and sediment transport is possible, supporting the design concept that a series of barriers may be used to stop volumes of debris larger than are possible using only one barrier. The future for these barrier concepts looks promising because these barriers represent the state of art for such applications and are superior to many other available options.

• 대한전자공학회논문지
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• 제26권5호
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• pp.1-9
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• 1989

2진 디지탈 전송시스템에서 보다 나은 전송효율을 얻기 위해서는 재역제한이 필요하다. 그러나 대역제한을 하는 경우 일반적으로 부호간의 간섭현상(ISI:intersymbol interference)이 발생되는데 본 논문에서는 최소의 부호간의 간섭현상과 최대의 저지대역 (stop band) 손실을 가진 대역제한 필터를 설계하기 위해 첫째, 2진 횡단선 필터(BTF:binary transversal filter)와 아나로그 필터를 결합시킴으로써 아나로그 필터를 이용하여 시간영역에서 2진 횡단선 필터에서 발생되는 구형펄스의 계단응답을 구해 부호간의 간섭현상이 최소가 되는 값을 찾았다. 둘째, 대역 제한을 위해 주파수영역에서 원하는 필터 특성과 오차를 최소화시켜 2진 횡단선 필터에서의 저항치(Tap계수)를 구해 최적필터를 설계하는 알고리듬을 제시하였다. 또한 저항치를 3, 5, 7개를 설정했을 경우 시뮬레이션 예를 보였는데 7개 설정했을 시는 약-30dB 정도의 리플(ripple)이 발생됨을 확인할 수 있었다.

• Archives of Pharmacal Research
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• 제29권12호
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• pp.1154-1157
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• 2006

The ermK gene from Bacillus lichenformis encodes an inducible rRNA methylase that confers resistance to the macrolide-lincosamide-streptogramin B antibiotics. The ermK mRNA leader sequence has a total length of 357 nucleotides and encodes a 14-amino acid leader peptide together with its ribosome binding site. The secondary structure of ermK leader mRNA and a leader peptide sequence have been reported as the elements that control expression. In this study, the contribution of specific leader peptide amino acid residues to induction of ermK was studied using the PCR-based megaprimer mutation method. ermK methylases with altered leader peptide codons were translationally fused to E. coli ${\beta}-galactosidase$ reporter gene. The deletion of the codons for Thr-2 through Ser-4 reduced inducibility by erythromycin, whereas that for Thr-2 and His-3 was not. The replacement of the individual codons for Ser-4, Met-5 and Arg-6 with termination codon led to loss of inducibility, but stop mutation of codon Phe-9 restored inducibility by erythromycin. Collectively, these findings suggest that the codons for residue 4, 5 and 6 comprise the critical region for induction. The stop mutation at Leu-7 expressed constitutively ermK gene. Thus, ribosome stalling at codon 7 appears to be important for ermK induction.

• Journal of Advanced Marine Engineering and Technology
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• 제38권6호
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• pp.723-729
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• 2014

스마트폰의 블루투스 통신기술을 원격 제어 시스템에 적용하였을 때, 전파 감쇠와 간섭 등으로 인한 통신오류는 원격 조종 거리의 제한 및 제어 대상 기기의 조종 불능과 오동작의 원인이 된다. 본 연구에서는 통신 오류의 영향을 최소화하고, 또한 통신 장애로 인해 제어 대상 기기가 조종 불능상태에 빠졌을 때 시스템이 이를 감지하고 대처하도록 하기 위한 방편으로, 블루투스 원격 통신 시스템에 재전송 지속성이 조절되는 S/W ARQ를 이용하는 방법을 제안한다. 본 연구에서는 블루투스 모듈이 장착된 RC카(Remote control car)와 이를 조종하기 위한 스마트폰 애플리케이션을 구현한 다음, 제안하는 방법을 시험하였다. 몇 가지 통신 환경에서 시스템을 실험한 결과, S/W ARQ를 적용하였을 때 통신 가능한 거리가 최소한 30% 이상 늘어났음을 확인할 수 있었다. 뿐만 아니라, 통신 장애가 발생하여 조종이 어려운 경우 S/W ARQ가 적용된 시스템은 즉시 구동을 멈추어 오동작을 회피함을 확인하였다.