• 문화기술의 융합
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• 제5권3호
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• pp.125-130
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• 2019

2019년 하노이에서 열린 체 2차 북미회담은 공동 합의를 도출하지 못한 채 결렬되었다. 본 논문은 마틴과 화이트(2005)의 평가어 체계를 근간으로 총 8개의 사설들, 구체적으로는 4개의 주요 미국 언론들의 사설들과 4개의 한국 언론들의 사설들을 평가어들을 포함한 언어적 표현들을 중심으로 분석하였다. 분석 결과 뉴욕타임즈, USA투데이, 워싱턴 포스트, 월스트리트 저널의 사설들 중 월스트리트 저널을 제외한 3개의 언론들은 모두 회담 결렬의 원인을 트럼프 대통령 개인으로 귀속시키며 부정적 평가어로 입장을 전달함을 알 수 있었다. 그러나 4개의 신문 사설에서는 한반도의 비핵화나 평화에 대한 우려에 대한 내용을 담고 있지 않았다. 반면 한국의 언론들은 모두 회담 결렬의 원인보다는 향후 방향에 대해 중점을 두고 있었는데, 두 언론은 부정적 행위평가어를 이용하여 문제점과 우려를 제기했지만, 다른 두 언론은 한겨레신문과 경향신문은 향후 대응과 입장에 중심을 두었고 부정적 평가어보다는 당부와 조언의 언어적 자원을 활용하고 있음이 밝혀졌다. 이를 통해, 담론 소비에 있어 양국의 언론들은 각자의 입장을 전달하는 데 있어 부정적인 평가어를 선호한다는 점, 그리고 기대와 당부를 전달할 때는 평가어보다는 보조 용언과 같은 언어적 표현을 사용한다는 것을 알 수 있었다.

• 대한조선학회논문집
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• 제33권1호
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• pp.124-134
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• 1996

본 연구에서는 LNG선의 화물하역 중 비상 상황시 펌프를 정지시키고 선박측의 긴급 차단 밸브 및 육상측의 정지 밸브를 폐쇄시킬 때, 관내 유체의 급격한 속도변화에 의하여 발생하는 비정상 유동 상태인 서지(Surge)현상의 원인을 고찰하고, 이 때 발생하는 상승압력과 유량의 변화를 계산하였다. 해석 결과에 의하면 서지현상에 의한 과도한 압력상승은 선박측의 긴급 차단 밸브 및 육상측의 정지 밸브의 종류와 이들의 폐쇄 시간, 그리고 배관 배치에 크게 영향을 받음을 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.471-477
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• 1998

A constant flow-rate control valve provides effective distributions and controls of running water in a pipe system. The noise characteristics were measured to reveal the noise sources depending on pressure differences across a valve. Valve noise is mostly dominated by bubble dynamics under cavitating conditions. In this study, the sound powers from a flow control valve of constant flow rates are effectively normalized. Flow-excited dynamic systems for which there is no strong coupling between the flow and the system response can be described using a linear source-filter model. On this assumption, the normalized sound powers can be decomposed of noise source function and a response function. The source spectra in, terms of cavitation frequency show cavitation events occurring at narrow banded frequencies greater than 10 kHz. There also possibly exist two kinds of cavitating modes based on our experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.735-740
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• 2001

In the nuclear power plant, emergency core coolant system(ECCS) is furnished at reactor coolant system(RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, it occurs thermal stratification phenomena in case that there is the mixing of cooling water and high temperature water due to valve leakage in ECCS. This thermal stratification phenomena raises excessive thermal stresses at pipe wall. Therefore, this phenomena causes the accident that reactor coolant flows in reactor containment in the nuclear power plant due to the deformation of pipe and thermal fatigue crack(TFC) at the pipe wall around the place that it exists. Hence, in order to fundamental identification of this phenomena, it requires the experimental research of modeling test in the pipe flow that occurs thermal stratification phenomena. So, this paper models RCS and ECCS pipe arrangement and analyzes the mechanism of thermal stratification phenomena by measuring of temperature in variance with leakage flow rate in ECCS modeled pipe and Reynold number in RCS modeled pipe. Besides, results of this experiment is compared with computational analysis which is done in advance.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.124-130
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• 1999

Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stoke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air may be made to flow inter-mittently through a pipe. In this paper an exhaust system simulator of engine was used to experi-mentally analyze the decrease in flow rate at high rotation speeds and to determine what variables other than rotational speed give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.

• 한국기계가공학회지
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• 제9권5호
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• pp.90-95
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• 2010

The dynamic instability and natural frequency of elastically restrained pipe conveying fluid with the attached mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using extended Hamilton's Principle. The influence of attached mass and its position on the dynamic instability of a elastically restrained pipe system is presented. Also, the critical flow velocity for the flutter and divergence due to the variation in the position and stiffness of supported spring is studied. Finally, the critical flow velocities and stability maps of the pipe conveying fluid with the attached mass are obtained by changing the parameters.

• Journal of Advanced Marine Engineering and Technology
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• 제38권8호
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• pp.961-967
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• 2014

In onshore and offshore plant engineering, a broad use of pipe system have been achieved and accordingly related technologies has been developed especially in the field of flow control valves. The aim of this study is to suggest the quadruple offset butterfly valve for bi-directional applications which show equivalent operating torque characteristics of the triple offset butterfly valve. Seat design parameters for the quadruple offset butterfly valve are determined by the proposed method utilizing both ANOVA (analysis of variance) and the orthogonal array. Through additive model considering the effect of design parameters on seating torque, mean estimation is performed and thus its optimization results are verified by design of experiment results. The insight obtained from the present study is beneficial for valve design engineers to develop reliable and integrated design of the quadruple offset butterfly valve.

• Journal of Advanced Marine Engineering and Technology
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• 제19권1호
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• pp.28-35
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• 1995

The fluid flow for a energy transfer is essential for the design and operation of power plants, petrochemical plants and ships including a process. When the operating conditions of a plant are changed or any transitional event occured, the flow controls of a fluid must be performed to follow the new operating state or mitigate the results of a event. Generally these flow controls to accommodate the new operating state of a plant are made by the use of various valves. The refore the design of valves and the related techniques are very important to the system and component designs. However the system and component design are not familiar with the practical theory of the valve since the derivative procedures of the flow equations in a valve are difficult and it is not easy to found the theoretical foundamentals and informations about the design of a valve from the present references. In this study the flow equations applicable to a valve for liquid are theoretically derived in detail. And the definition of valve reynolds number and its boundary values between the tubulent and laminar flow is described compared with the values of a circular pipe flow.

• 한국기계가공학회지
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• 제11권4호
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• pp.90-96
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• 2012

The forced vibration response characteristics of a elastically restrained pipe conveying fluid with attached mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effects of attached mass and spring constant on the forced vibration characteristics of pipe at conveying fluid are studied. The forced deflection response of pipe with attached mass due to the variation of fluid velocity is also presented. The deflection response is the mid-span deflection of the pipe. The dimensionless forcing frequency is the range from 0 to 16 which is the first natural frequency of the pipe.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.380-384
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• 2010

A disturbance flow at piping bands and discontinuous regions such as a valve, a header has a intense broadband internal pressure field and a sound field which are propagated through the piping system The fields becomes the source of a vibration of this piping system. Intense broadband disturbance flow at a discontinuous region such as elbows, valves or headers generates an acoustical pulsation. The pulsation becomes the source of structural vibration at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level vibration due to the pressure pulsation affects the reliability of the plant piping system. This paper discusses the high vibration and the branch vent pipe's failure of condensate-water supply piping system due to the effect of acoustical pulsations by flow turbulence from the flow control valves of globe type in a power site.