• Journal of Advanced Marine Engineering and Technology
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• 제25권5호
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• pp.1065-1075
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• 2001

It is common knowledge amongst electrical and marine engineers that short-circuit in electrical system may cause large mechanical torque on generator and prime mover However, it is not so widely known that the faulty synchronizing of generators may cause even higher torques than that of short-circuit. In this study, the transient phenomena related to the parallel running of synchronous generators are analyzed and the exact computer simulation method is proposed. In result, maximum transient torque and current take place in case of $120^{\circ}$ voltage angle difference between Master and Slave and that may develop higher torque than the short-circuit according to a condition of synchronizing. When synchronizing in power system using only two generators higher torque and current occur Master, but using multimachine system those occur to Slave. The short-circuit of marine generator does not happen frequently but faulty synchronizing sometimes takes place, therefore, it is necessary for designers to consider these phenomena.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.277-282
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• 2001

Partial rotor rub occurs when an obstacle on the stator of a rotating machinery disturbs the free whirling motion of a rotor, which is more common than full annular rub for the cases of rubbing in rotating machinery. The nonlinearity due to the intermittent contacts and friction during partial rotor rub makes the phenomenon complex. The several nonlinear phenomena of superharmonics, subharmonics, and jump phenomenon are demonstrated for the partial rub using an experimental apparatus in this study. A piecewise-linear model and a rebound model using the coefficient of restitution are investigated on the basis of experimental observations in order to adopt as an analytical model of the contact between the rotor and stator during whirling motion. The contact stiffness, coefficient of restitution, and friction coefficient for the contact during partial rub are calculated from the comparison between the numerical simulation and the experimental results. Also, the numerical simulations for the model of partial rub are done for the various system parameters of clearance, contact stiffness, and friction coefficient in order to find the nonlinear behavior of partial rotor rub.

• 산업공학
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• 제21권2호
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• pp.161-169
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• 2008

Normally, suppliers have to decide on what, how much, and when to replenish stocks of goods based on a data flow generated by a vendor managed inventory(VMI) system. But information from supply chain is often misleading. It is common for such data to be distorted by a lack of coordination and synchronization across several business entities managing different supply chain operations. This phenomenon is called the 'bullwhip effect(BwE)'. Many researchers, working over many years, have studied the reasons for the BwE. They have proposed various remedies, but this phenomenon persists. Though overlooked in previous research, this paper reveals that the 'lot size' of a supply chain of distribution is indeed the main cause of the BwE. In addition, some problems in the existing methods of measuring the BwE are identified and a revised much improved method of measurement is suggested.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.254-261
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• 1997

In desingin plate bridges, the width-thickness ratio of flanges and webs are proportioned in such that the premature local buckling of flanges and webs prior to achievement of the full strength of plate-girders must be prevented. It is the common practive in most design codes that the flange local buckling strength and the web bend buckling strength are separately computed. In most practical plate girders, however, the flange buckles simultaneously when web bend-buckling occurs, vice versa. The primary purpose of the present study is to investigate the phenomenon, which may be called flange-web interactive buckling. Using the eight-node shell element available in the commercial multi-purpose program ABAQUS, the phenomenon was quantitatively investigated. Also presented are the effects of various factors such as the ratio of flange slenderness ratio to the web slenderness ratio, the ratio of flange width to the web depth, and the longitudinal stiffeners. A series of comparative studies with various design codes show that the present study provides more accurate and effective design basis in proportioning the flanges and webs.

• 건축역사연구
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• 제4권1호
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• pp.141-151
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• 1995

For many social scientists, the comparative method has been a part of the common enterprise of describing, explaining, and developing theories about socio-cultural phenomena. However, it is rare that comparison has been methodologically considered in architectural history in spite of the usefulness for understanding the similarities and differences among architectural styles. This research emphasizes the importance of comparative methodology in architectural history and proposes an example which can be introduced from the comparative method for social studies. The application in this study is based on the assumption that an architectural phenomenon is a kind of social phenomenon and comparative method in social study can be applied to architectural history. The method is to generate and test hypotheses through establishing functional correlation between variables treated as the objective facts that differentiate one type of building from another.

• 설비공학논문집
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• 제29권12호
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• pp.628-637
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• 2017

This study was conducted to present an effective control method for the common duct system to uniformly discharge volume flow rate exhausted from the kitchen and bathroom of each household in an apartment regardless of the position of household. Since the common duct system is installed vertically and the ventilator is installed in the terminal, the static pressure of each household decreases when vertical height increases. Therefore, the volume flow rate exhausted from each household is different. In order to improve such a phenomenon, a constant air volume damper shall be installed in a branch duct coupled with a common vertical duct system. The selected ventilator should also be able to handle the maximum volume flow rate considering diversity factor. Therefore, a uniform volume flow rate must be exhausted from all households where the hood is operated. This paper mainly focuses on suggestion of an optimum exhaust control method by comparing exhaust performance of each household according to the presence or absence of a constant air volume damper.

• 대한임상검사과학회지
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• 제49권3호
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• pp.316-321
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• 2017

빗장밑혈류빼앗김증후군은 좌측 몸쪽부분 빗장밑동맥 혹은 팔머리동맥에 심한 혈관 협착이나 폐색이 원인이 되어 발생한다. 병변이 있는 부위에서는 제한적이며, 불충분한 혈류가 발생하여 반대쪽으로부터 연결혈관을 통해 일부 혈액이 유입될 수 있다. 이러한 현상을 빗장밑혈류빼앗김현상이라고 한다. 이중초음파검사는 빗장밑혈류빼앗김현상을 측정하는데 유용한다. 빗장밑혈류빼앗김현상을 보이는 일부 환자에서는 척추뇌바닥혈류부전 혹은 허혈성 말초동맥질환 증상을 호소한다. 빗장밑혈류빼앗김증후군은 빗장밑혈류빼앗김현상과 더불어 신경학적 증상이 반드시 동반될 경우로 정의할 수 있다. 저자는 팔머리동맥의 심한 협착을 보이는 환자에서 척추동맥과 더불어 바깥목동맥과 전방순환계를 담당하는 온목동맥 및 속목동맥에서 이중초음파검사를 이용한 혈류빼앗김현상이 관찰된 증례를 보고하고자 한다.

• 근관절건강학회지
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• 제28권2호
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• pp.152-160
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• 2021

Purpose: This study, using the International Classification for Nursing Practice, aimed to identify the phenomenon of family nursing care, and the factors affecting it, for high-risk and frail older persons who have a significant need for home healthcare services. Methods: This study was conducted using secondary data collected by students who interviewed 93 healthcare subjects in a health center. The data was used to analyze the general characteristics, health-related characteristics, and confirmed problems of family nursing phenomena of the subjects. Independant t-test, Pearson correlation coefficient, and multiple linear regression were used for the data analysis. Results: The mean age of the subjects was 82.4±6.3 years. The most common problem of the family nursing phenomenon were unhealthy lifestyle, disturbance in family communication, and lack of family interaction in the community. People with greater family nursing phenomenon problems reported a higher degree of frailty and depression, lower quality of life and self-rated health. The factors that influence the family nursing phenomenon of frail older persons are the problems of mobility and hearing. Conclusion: Physical and psychological problems associated with aging can cause not only personal, but family functional problems as well. Therefore, a comprehensive family-oriented support program is required.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.63-74
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• 2022

Repressive measures in the Crimea against the Ukrainian media and the ban on the entry of international and Ukrainian monitoring missions created the conditions for the function of providing information to be performed by representatives of civil society. Such a phenomenon was called Crimean citizen journalism and became a post-occupation phenomenon characteristic of the Crimean information sphere. The journalists' activities are aimed at reporting on human rights violations and repression against Ukrainian citizens who find themselves in conditions of information bans and restrictions. Crimean citizen journalism, which connects the peninsula with the mainland of Ukraine, is monothematic in nature, and its emergence has become a form of nonviolent resistance to the occupation of Crimea. The purpose of the study is to cover the characteristic features, the development of common Crimean citizen journalistic movement features as a social phenomenon, a phenomenon that arose after the occupation through the identification of a modern journalist portrait. The study uses the general scientific method of empirical research as the main one, the sociological method of a questionnaire survey, as well as the methods of classification, generalisation, observation, statistical calculation. An analysis of a survey of Crimean citizen journalists demonstrates the existence of an active, mobile community in Crimea that seeks to provide information and human rights nonviolent resistance to the occupation.

• 턱관절균형의학회지
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• 제13권sup호
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• pp.1-8
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• 2023

Objectives: Parkinson's disease (PD) is currently the most rapidly increasing degenerative brain disease due to population aging and westernization of lifestyle. Levodopa is the most commonly used drug to manage PD symptoms. However, levodopa has a problem in that the wearing-off phenomenon occurs as the duration and dose of administration increase. In order to investigate the wearing-off phenomenon in PD patients and devise countermeasures, we conducted a questionnaire survey in Korea. Methods: For the study, a questionnaire with a total of seven items was prepared. Part IV of the MDS-UPDRS (Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale) and the WOQ-9 (9-symptom Wearing-off Questionnaire) were used as references. Results: Of the 48 patients who completed the questionnaire, all 47 patients who completed the questionnaire experienced the wearing-off phenomenon. Only one of the patients diagnosed with PD a year ago did not experience the wearing-off phenomenon. Patients frequently mentioned a lack of sleep and stress as aggravating factors for wearing-off. They also stated that in order to resolve the off-state, they walked, massaged, warmed up the body, stretched and exercised. Conclusions: Because wearing-off is such a common occurrence, it is thought necessary to develop wearing-off prevention and resolution measures that PD patients can use in their daily lives.