• 제목/요약/키워드: Variation and change

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가스성분 및 용접와이어의 변화에 따른 SS400소재의 $CO_2$용접에서 용접부의 상태변화 고찰 (Study of Weld Part Status Change by $CO_2$ Welding According to the Variation of Gas Composition and Welding Wire on SS400 Material)

  • 김법헌;김원일;최창;박용환
    • 한국기계가공학회지
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    • 제11권5호
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    • pp.129-136
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    • 2012
  • On this study, $CO_2$ gas, net of Ar gas, and mixed gas in solid wire(AWS ER 70S-6) and flux cored wire(AWS E71T-1) were used to weld on Mild steel(SS400). After the progress, the status changes of the welds in Mild steel(SS400) were investigated with compositional changes. For stable experiments, welding was conducted using the automatic feeder. Radiation testing, hardness testing, chemical composition analysis and penetrated cross-section were measured. Through these experiments, shapes of penetrated cross-section, chemical composition changes, and weld defects according to the variation of welding gas were known. Weld defects and weld cross-sectional shapes by the variation of the welding voltage were also detected.

Effects of Resistivity Variation in a Very Low Temperature on the Characteristics of Induction Motors

  • Kim, Beom Jin;Kim, Jin Sung;Park, Gwan Soo
    • Journal of international Conference on Electrical Machines and Systems
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    • 제2권1호
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    • pp.45-50
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    • 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.

일반화최소분산 적응제어를 이용한 유압 서보계의 특성개선에 관한 연구 (Characteristics Improvement of Hydraulic Servosystem by Using Generalized Minimum Variance Adaptive Control)

  • 박용호;김기홍;이진걸
    • Journal of Advanced Marine Engineering and Technology
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    • 제27권3호
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    • pp.388-394
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    • 2003
  • Hydraulic system is difficult to obtain a suitable performance due to the nonlinearity load pressure change and system parameter variation. The requirement of control a1gorithm has been complex in order to satisfy the performance. The adaptive control is a control method which is suggested to achieve the control object under the plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp. the adaptive control could keep the characteristics of closed-loop system generally. In this study. a method of combined generalized minimum variance adaptive control (GMVAC) and output error feedback is proposed, in order to solve the problem of non-minimum phase of plant and the vibration and overshoot in initial response. The control performance according to the variation of characteristics of plant is evaluated by changing the supply pressure. The experimental results show the effectiveness of the proposed scheme.

시스템 사고를 통한 생태계서비스의 trade-off 관계 고찰 (An Analysis of Ecosystem Service's trade-off through Systems Thinking)

  • 함은경;김민;전진형
    • 한국시스템다이내믹스연구
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    • 제16권2호
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    • pp.75-100
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    • 2015
  • The purpose of this study is to analyze causation of Ecosystem service's trade-off(ES trade-off) and to establish baseline data for wise spatial planning and management. In order to understand why and how ES trade-off occurs, systems thinking and causal loops were employed. The causal loop of ecosystem service creation cycle includes profits quantification process, decision making process, spatial planning and management process, and ecosystem services creation process. The profits quantification process has a limitation that all ecosystem service categories were not included in profits quantification, because quantification method for cultural services is insufficient. These problems led to unequal discussion opportunity in decision making process. ES trade-off occurs through transition of ecosystem function in spatial scale and temporal scale. In spatial scale, land-use variation and resource-use variation contribute to change an ecosystem function for different ES category by spatial planning and management. In temporal scale, a change of an ecosystem function for different ES category is influenced by ecological succession, seasonal change and land cover variation, which are parameter from environmental features. This study presented that spatial planning and management should ecosystem service assessment in order to enhance balanced ecosystem services.

3 차원 벤딩 머신에서 정밀 성형을 위한 공정 개발에 관한 연구 (A study on the process for precision forming by 3-dimension bending machine)

  • 김현진;임상헌;이춘만
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 춘계학술대회 논문집
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    • pp.1897-1900
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    • 2005
  • The purpose of this study is to investigate the bending process for manufacturing of sound pipe by 3 dimension bending machine. The arbitrarily-bended pipe is widely used in a heat exchanger system. The pipe should be formed precisely for assembling of heat changer. And, spring back effect and variation of the pipe thickness should be controlled effectively. We described the change of spring back amount and thickness variation of the pipe according to the change of bending radius and bending angle by FEM analysis. The analysis is adopted the elasic-plastic analysis and contact analysis on MARC software.

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심박변화 분석을 이용한 장면시자극에 대한 감성측정에 관한 연구 (Human Sensibility Measurement for Visual Picture Stimulus using Heart Rate Variability Analysis)

  • 권의철;김동윤;김동선;임영훈;손진훈
    • 감성과학
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    • 제1권1호
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    • pp.93-103
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    • 1998
  • In this paper, we present change of human sensiblity when the 26 healthy female subjects were exposed with visual picture stimulus. We used Intermational Affective Picture System as the visual stimulus. The methods are AutoRegressive(AR) spectrum which is a linear method and Return Map which is a nonlinear mithod. SR spectrum may variability(HRV). The LF/HF of HRV and the variation of Return Map were analyzed from ECG signal of the female subjects. Return Map of RR intervals were analyzed by computiong the variation. When the subjets were stimulated by the pleasant pictures, LF/HF and variation were decreased compared with unpleasant stimulus, We may obtain good parameters for the measurement of the change of human sensibility for the visual picture stimulus.

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정밀 파이프 성형을 위한 벤딩 공정 개발에 관한 연구 (A Study on the Bending Process for Precision Pipe Forming)

  • 김현진;이춘만
    • 한국정밀공학회지
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    • 제24권6호
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    • pp.58-65
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    • 2007
  • The arbitrarily-bended pipe is widely used in a heat exchanger system. Thus, the pipe bending process has important role in performance and productivity of heat exchanger system. The purpose of this study is to investigate the bending process for manufacturing of sound pipe. And, the spring-back effect and the variation of pipe thickness should be controlled effectively. The change of spring-back ratio and the thickness variation of pipe according to the change of bending radius, bending angle and pipe thickness are analyzed by FEM analysis. The analytic results are compared with the experimental data, accordingly the results show good agreement. The method of the analysis can be applied for manufacturing of precision bended pipe.

낙동강 하구역 진우도내 지형변동에 따른 식생면적의 변화 (Variation in Vegetation Area caused by Topographical Change at Jinudo in the Nakdong Estuary)

  • 류성훈;이인철;박소영
    • 한국해양공학회지
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    • 제23권4호
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    • pp.19-24
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    • 2009
  • In order to analysis the variation in vegetation area caused by topographical change at Jinudo in the Nakdong estuary, we used aerial photographs of Jinudo from 1998 to 2006. To extract an accuracy shoreline from these aerial photographs, a tide calibration was performed. We also estimated the annual variation in topographic area and vegetation area, and then analyzed the relationship between them by a correlation analysis. The following results were obtained: 1) The calibrated shoreline distance of Jinudo from 1998 to 2006 was estimated to have a range of (-)1,927 cm to (+)4,671 cm. 2) Annual changes in the topographic area and vegetation area in Jinudo have been increasing gradually from 1998, and the correlation coefficient between topographic area and vegetation area is 0.97. 3) The estimated topographic areas were with following order: southern (III), eastern (IV), northern (II) and western (I), while for the vegetation area, the order was southern (III), northern (II), eastern (IV) and western (I). 4) The vegetation area of the southern region (III) of Jinudo had the largest size among the regions, and was calculated to be $4.3{\sim}5.4$ times larger than the eastern region (IV).

스로틀 개폐에 따른 가솔린 엔진의 비정상상태 유량변화 특성 (Characteristics of the Air Flow Variation by Throttle Step Change in a Gasoline Engine)

  • 박경석;고상근;노승탁;이종화
    • 한국자동차공학회논문집
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    • 제4권3호
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    • pp.92-101
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    • 1996
  • In a gasoline engine, the characteristics of air flow is very important not only for the design of the intake system geometry bout also for the accurate measurement of the induction air mass. In this study, an air flow rate measurement of the induction air mass. In this study, an air flow rate measurement was conducted by using the hot wire flow meter at the upstream of the intake port and the throttle. At the upstream of the throttle, the overshoot phenomena of the air flow rate by fast throttle opening were analyzed with choked flow. At the upstream of the intake port, the cylinder variation of the air flow rate and the difference between fast throttle opening and closing were showed during the unsteady state by the throttle step change. The results of this study can be used for the design of the throttle valve geometry and cylinder by cylinder control.

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A finite element based approach to observe hydrodynamic pressure in reservoir adjacent to concrete gravity dam

  • Santosh Kumar, Das;Kalyan Kumar, Mandal;Arup Guha, Niyogi
    • Ocean Systems Engineering
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    • 제12권4호
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    • pp.385-402
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    • 2022
  • This paper deals with the study of hydrodynamic pressure in reservoir adjacent to the concrete gravity dam subjected to dynamic excitation. Widely famous finite element method is used to discretize the reservoir domain for modelling purpose. Pressure is considered as nodal variable following Eulerian approach. A suitable nonreflecting boundary condition is applied at truncated face of reservoir to make the infinite reservoir to finite one for saving the computational cost. Thorough studies have been done on generation of hydrodynamic pressure in reservoir with variation of different geometrical properties. Velocity profile and hydrodynamic pressure are observed due to harmonic excitation for variation of inclination angle of dam reservoir interface. Effect of bottom slope angle and inclined length of reservoir bottom on hydrodynamic pressure coefficient of reservoir are also observed. There is significant increase in hydrodynamic pressure and distinct changes in velocity profile of reservoir are noticeable for change in inclination angle of dam reservoir interface. Change of bottom slope and inclined length of reservoir bottom are also governing factor for variation of hydrodynamic pressure in reservoir subjected to dynamic excitation.