• Journal of international Conference on Electrical Machines and Systems
• /
• 제2권1호
• /
• pp.45-50
• /
• 2013

This paper presents design of induction motor in very low temperature for LNG main cargo pump and comparison of two motors. One is the motor for using in room temperature and another is the motor for using very low temperature. This paper designs with Equivalent circuit Method and uses Finite Element Method to analysis. The motor for very low temperature considers variation of coil resistivity due to temperature change and compare torque characteristic with the motor for room temperature. Design element of motor for very low temperature considers resistivity variation following temperature change on going through this paper. The result shows that two types of motors are almost same torque curve characteristic even though they are not the same environment.

• Journal of Advanced Marine Engineering and Technology
• /
• 제23권1호
• /
• pp.79-87
• /
• 1999

The most part of the faculty drop a trouble and damage of machine equipment even if whatever cause they break out take place at local and trifling place and the factor dominating their trouble is due to wear debris occurred in the lubricated machine moving surface. This study has been car-ried out to identify morphology of wear debris on the lubricated machine moving system by means of computer image analysis. Namely the wear debris contained in lubricating oil extracted from movable machine equipment will be filtered through membrane filter(void diameter 0.45${\mu}m$) and will be analyzed with its data information such as 50% volume diameter aspect roundness and reflectivity. Morphological characteristic of wear debris is easily distinguished by four shape parameters it is necessary to divide small class of every 100 wear debris in total wear particles in order to distinguish morphological characteristic of wear debris more easily by computer image analysis. We are sure that operation condition diagnosis of the lubricated machine moving surfaces is possible by computer image analysis.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제13권2호
• /
• pp.87-98
• /
• 2013

Accelerated degradation tests (ADTs) measuring failure-related degradation characteristic at the accelerated condition are widely used to assess the reliability of highly reliable products. Often, however, little degradation could be observed even in single-stress ADTs due to the high reliability of test unit, and as a result poor estimate of the reliability may be obtained. ADTs with multiple stress variables can be employed to overcome such difficulties. In this paper, optimal ADT plans with two stress variables are developed assuming that the degradation characteristic follows Weibull distribution by determining the stress levels, the proportion of test units allocated to each stress level such that the asymptotic variance of the maximum likelihood estimator of the q-th quantile of the lifetime distribution at the use condition is minimized.

• 천문학회보
• /
• 제44권1호
• /
• pp.68.3-68.3
• /
• 2019

Even though the initial mass function (IMF) of the first generation of stars played important roles in reionization of the universe, subsequent star formation, and chemical enrichment of the universe, it is still very uncertain. In this study, among the several indirect ways of estimating the IMF of the population III (Pop III) stars, we make use of extremely metal-poor (EMP; [Fe/H] < -3.0) stars in the Milky Way, in order to infer the characteristic mass range of Pop III stars. As the progenitors of many of the EMP stars are known to be Pop III stars, we attempt to construct the characteristic mass range of the progenitors (e.g., Pop III stars) of the EMP stares by comparing their observed abundance pattern of various chemical elements with chemical yields from supernova models.

• Journal of Contemporary Eastern Asia
• /
• 제19권2호
• /
• pp.216-233
• /
• 2020

Over the last 70 years, South Korea has gone through countless provocations from North Korea. Provocation is something that must be delicately calculated before the actual action, since it can be extended to a serious conflict. Among the possible factors, this paper focuses on the leader's characteristic, because 1) under North Korean dictatorship, the leader's thoughts are critical influence to policies and 2) personal characteristic, especially if it is the dictator's, hardly changes even when the external circumstances change. The purpose of this paper is in analyzing the correlations between North Korean leader's characteristics and provocation pattern. First, three generations of Kim Il-sung, Kim Jong-il, and Kim Jong-un's personal characteristics will be described. Next, particular provocation features in respective leader's period will follow. Lastly, how each leader's characteristic and concerns were reflected on the provocations will be analyzed.

• Kyungpook Mathematical Journal
• /
• 제57권2호
• /
• pp.327-329
• /
• 2017

For any even integer n, we show that there exists a log Calabi-Yau threefold (Y, D) such that the Euler characteristic of Y is n. Furthermore Y is smooth and D is smooth anticanonical section of Y that is a K3 surface.

• 한국보건간호학회지
• /
• 제32권2호
• /
• pp.304-318
• /
• 2018

Purpose: This study examined the characteristic of the Injury Severity Score (ISS) of Korean geriatric patients with a traumatic injury in a nationally representative sample to determine the optimal cutoff of ISS of mortality according to age. Methods: The subjects were 3,018 non-elderly patients and 1,584 elderly patients with an ISS and Korean Triage and Acuity Scale (KTAS) in 2016 from the data of the Health Insurance Review and Assessment Service. The traumatic characteristics of the elderly and non-elderly were compared by stratifying the ISS. Receiver Operating Characteristic (ROC) curve analysis was used to find the optimal cutoff of ISS of mortality according to age. Results: The elderly were more prone to severe trauma than the non-elderly were. The distribution of KTAS grades was lower, even though the severity of ISS was as high as that of the non-elderly. The optimal cutoff score of the ISS for mortality in the ROC curve was lower in elderly over 65 years than in the other age group. Conclusion: The elderly are more prone to severe trauma and death than non-elderly, even though their ISS is low. Therefore, a strategy to prevent elderly from experiencing serious trauma and managing their geriatric trauma actively is needed.

• 한국콘텐츠학회논문지
• /
• 제5권5호
• /
• pp.248-254
• /
• 2005

기존의 버퍼 관리 방법은 TCP 트래픽의 "burstness" 특성으로 인해 손실 없는 전송만으로는 GFR이 요구하는 최소 전송률 보장과 공평성을 제공하기 어렵다. 본 논문에서는 GFR이 요구하는 최소 전송률 보장과 높은 공평성을 제공하기 위하여 기존의 버퍼관리 기법에 퍼지 이론을 적용한 버퍼관리 알고리즘을 제안하였다. 제안된 알고리즘은 태깅정보, 버퍼 점유량, VC의 부하정도로 구성된 세 개의 파라미터를 이용하여 패킷 폐기를 결정한다. 시뮬레이션 결과 MCR의 크기가 커질수록 제안된 알고리즘의 수율과 공평성이 우수하였으며, 스위치에서 버퍼의 크기 변화에서도 Double-EPD나 DFBA는 비슷한 성능을 보였고, 제안된 알고리즘은 좋은 수율과 공평성을 제공한다.

• 정보과학회지
• /
• 제5권1호
• /
• pp.42-49
• /
• 1987

Digital 回路에서의 고장을 검출하기 위해서는 적당한 信號를 入力단자에 加하여 出力端子에서 그 異狀有無를 判別하게 되는데 이때 印加되는 信號 즉 test pattern의 數는 組合論理回路인 경우 入力變數가 n이라 할때 그 최대값은 2n 이 된다. 따라서 入力變數가 증가함에 따라 test pattern의 數는 급격히 증가하게 된다. 고장검출을 용이하게 하기 위해서는 가능한 한 最小의 test가 필요하게 된 다. 이 test pattern을 生成하는 방법에는 pandom test pattern生成法 등의 확율논 적인 方法[9], 一次元經路活性化法[6] Boolean Difference등과 같은 해석적인 방법 [7], D-Algorithm등과 같은 방법[4] 등이 있다. 또 Berger등은 分岐가 존재하지 않을 때, test pattern의 下限値를 정해주었으며 [6], 또 單一故障일 경우의 fault locating test를, 故障表를 사용하지 않고 그래프적인 方法으로 회로구조로 부터 직접 구하였다. [6].

• Earthquakes and Structures
• /
• 제22권1호
• /
• pp.53-64
• /
• 2022

This study proposes an intelligent semi-active isolation system combining a variable-stiffness control device and ground motion characteristic prediction. To determine the optimal control parameter in real-time, a genetic algorithm (GA)-fuzzy control law was developed in this study. Data on various types of ground motions were collected, and the ground motion characteristics were quantified to derive a near-fault (NF) characteristic ratio by employing an on-site earthquake early warning system. On the basis of the peak ground acceleration (PGA) and the derived NF ratio, a fuzzy inference system (FIS) was developed. The control parameters were optimized using a GA. To support continuity under near-fault and far-field ground motions, the optimal control parameter was linked with the predicted PGA and NF ratio through the FIS. The GA-fuzzy law was then compared with other control laws to verify its effectiveness. The results revealed that the GA-fuzzy control law could reliably predict different ground motion characteristics for real-time control because of the high sensitivity of its control parameter to the ground motion characteristics. Even under near-fault and far-field ground motions, the GA-fuzzy control law outperformed the FPEEA control law in terms of controlling the isolation layer displacement and the superstructure acceleration.