• 대한산업공학회지
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• 제27권3호
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• pp.315-327
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• 2001

This paper considers the problem of operation sequencing in nonlinear process planning, which is the problem of selecting and sequencing operations required to produce a part with the objective of minimizing the sum of operation processing costs and machine, setup and tool change costs. Main constraints are the precedence relations among operations. The problem can be decomposed into two subproblems: operation selection and operation sequencing. We suggest four simulated annealing algorithms, which solve the two subproblems iteratively until a good solution is obtained. Here, the operation selection problem can be solved using a shortest path algorithm. Application of the algorithms is illustrated using an example. Also, to show the performances of the suggested algorithms, computational experiments were done on randomly generated test problems and the results are reported. In particular, one of the suggested algorithms outperforms an existing simulated annealing algorithm.

• 한국정밀공학회지
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• 제30권2호
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• pp.185-193
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• 2013

The construction automation provides safer and more productive working environment of construction site. We developed the automation system of bolting operation for high-rise building in the previous research. However, this system has a weak point that the operation has to be processed in the air with the operator in the cabin. This weakness leads operators to considerably dangerous environment. Therefore, we proposed the tele-operation system in order to supplement this weak point. Furthermore, it leads more effective operation by application of more intuitive controller; spherical coordinate based Master Arm than the joystick in the Mobile Bolting Robot system. These proposed system and controller were evaluated based on Fitts' law paradigm, which is a general estimation method of speed accuracy of task. Through the experimental results, new developed tele-operation system is compared with the actual operation and it discloses distinctions between two systems. As a result, it is found that new developed teleoperation system can be possible to replace the operation in the cabin.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.61-66
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• 2012

Conventional method to transform vehicle driving condition to engine operation mode is to use vehicle road load under neutral gear and mechanical efficiency of drivetrain. But this method requires additional measurement of efficiency of drivetrain on a test rig. And this measurement is normally done at fixed speed and thus estimated accuracy of engine operation mode is not considered to be high enough. This study suggests new method to calculate engine operation mode for prescribed driving mode such as NEDC using vehicle coastdown test under gear engaged condition without measurement of mechanical efficiency of drivetrain. Coastdown test was done under neutral and gear engaged condition for comparison and also trial to extract mechanical loss of drivetrain was carried out. Calculated engine torque by conventional and newly suggested method was compared with actually measured torque of a vehicle on a chassis dynamometer during NEDC. Newly suggested method showed slightly higher accuracy of accumulated brake work during NEDC.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.209-214
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• 2007

This study is concerned with working hardening of bending operation on hydroforming parts. Generally, hydroforming parts having the complicated shape of the automobile, require a 3-dimentional bending operation. This operation involves several variations in the tube which are the thickness, the mechanical characteristics, the hardness, the circumference etc., on original tube. So, we study those variations and the affect on the hydroforming operation and hydroforming parts. We used two methods, one of which was computer simulation and the other the actual test in the plant.

• 대한기계학회논문집
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• 제18권1호
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• pp.223-231
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• 1994

When manufacturing mold dies, an operation sheet is required for each part of the mold dies. The consistent estimation of standard operation time in the operation sheet is difficult, because the estimation is mainly based on subjective judgement. In order to resolve it, concept of feature is introduced in this study. For CAD/CAPP integration, feature technology is being implemented to represent geometrical and technological information of part drawings. A feature database has already been designed, and then used to generate data for process and operation planning modules. Related to this former research, standard operation time is calculated using the feature information and tables used in a real factory.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.36-43
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• 2004

본 연구에서는 운전중인 직류전동기의 브러시를 임의로 회전하여 브러시와 정류자편에 불꽃을 발생시켰을 때, 초음파센서와 AE센서를 이용하여 각각의 기계적 노이즈 신호를 검출하였으며, 이를 주파수 스펙트럼으로 분석하였다. 또한 직류전동기의 브러시가 중성축에 정상적으로 위치하여 운전하고 있을 때, 초음파센서와 AE센서를 이용하여 각각의 자기적 노이즈 신호를 검출하였으며, 이를 주파수 스펙트럼으로 분석하였다. 그리고 직류전동기의 브러시를 임의로 회전한 경우의 기계적 노이즈 신호 및 브러시가 중성축에 위치한 경우의 자기적 노이즈 신호를 비교ㆍ분석하였다. 실험 결과, 운전중인 직류전동기의 브러시를 회전방향으로 임의로 회전하여 검출한 초음파의 기계적 노이즈 신호는 브러시가 중성축에 정상적으로 위치하여 검출한 초음파의 자기적 노이즈 신호보다 대략 2.5∼3.0배 증가되었다. 또한 운전중인 직류전동기의 브러시를 회전방향으로 임의로 회전하여 불꽃을 발생시켰을 때, AE의 기계적 노이즈 신호를 검출하여 주파수 스펙트럼으로 분석한 결과 주된 주파수 영역이 대략 1.3[MHz]∼l.5[MHz]인 것으로 나타났다

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2775-2780
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• 2007

The ballistic range has long been employed in a variety of engineering fields such as high-speed impact engineering, projectile aerodynamics and aeroballistics, since it can create very high-pressure states in a short time. Since the operation of the ballistic range includes many complicated processes, each should be studied in detail for the best operation of the device. One of the main processes which have a major influence in its operation is the compression of the driver gas. Most of the studies available in this field hardly discuss this process in detail and thus lack a proper understanding of its effect. In the present study, a computational analysis has been made to investigate the compression process in the pump tube of a ballistic range. The results obtained are validated with some experimental data. It is seen that the pump tube parameters and the piston mass significantly affect the compression process and the time to build up the required diaphragm rupture pressure.

• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.764-772
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• 2000

In this paper, an engine-CVT integrated control algorithm is suggested by considering the inertia torque and the CVT ratio change response lag in acceleration. In order to compensate for drive torque time delay due to CVT response lag, two algorithms are presented: (1) an optimal engine torque compensation algorithm, and (2) an optimal engine speed compensation algorithm. Simulation results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation point compared to the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed engine-CVT integrated control algorithms are compared with those of conventional CVT control, and It is found that optimal engine operation can be achieved by using integrated control during acceleration, and improved fuel economy can be expected while also satisfying the driver's demands.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.30-35
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• 2017

한국형발사체 발사대시스템의 지상기계설비는 수평상태로 총 조립된 발사체를 조립동에서 발사패드로 이송하여 기립 후 안착시키고, 발사체로의 추진제 공급을 위한 공급 및 분리장치를 제공하며 발사체 이륙까지의 기구학적인 동작과 기계적인 운용을 담당하는 설비이다. 본 논문에서는 한국형발사체의 요구조건을 충족시키기 위하여 개발 중인 지상기계설비들의 구성과 기능, 형상 설계 결과를 소개하고, 발사운용절차에 따른 각 장치들의 운용개념을 소개한다.