• 한국생산제조학회지
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• 제23권3호
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• pp.299-309
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• 2014

When using an automotive heating, ventilation, and air conditioning (HVAC) system, we can obtain fresh outside air while maintaining the interior vehicle temperature. In this study, a correction equation considering experimental data for automotive indoor air leakage is defined to simulate the ratio of fresh air to recirculated air in the automobile cabin. With this correction equation, numerical results are compared with experimental data and validated. The $CO_2$ concentration in the automotive cabin is evaluated by considering various boarding conditions and mass flow rates of the HVAC system. The $CO_2$ concentration model derived in this study is expected to be used to control the effective air conditioning and become a basic research tool for automotive air quality control system development.

• 한국분말재료학회지
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• 제20권4호
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• pp.291-296
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• 2013

SKD11 (ASTM D2) tool steel is a versatile high-carbon, high-chromium, air-hardening tool steel that is characterized by a relatively high attainable hardness and numerous, large, chromium rich alloy carbide in the microstructure. SKD11 tool steel provides an effective combination of wear resistance and toughness, tool performance, price, and a wide variety of product forms. The CNTs was good additives to improve the mechanical properties of metal. In this study, 1, 3 vol% CNTs was dispersed in SKD11 matrix by mechanical alloying. The SKD11+ CNT hybrid nanocomposites were investigated by FE-SEM, particle size distribution, hardness and wear resistance. The CNT was well dispersed in the SKD11 matrix and the mechanical properties of the composite were improved by CNTs addition. It shows good feasibility as cold work die tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.155-156
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• 2006

UV-NIL is a promising technology for the fabrication of sub-100 nm features. Due to non-uniformity of the residual layer thickness (RLT) and a strong possibility of defects, many UV-NIL processes have been developed and some are commercially available at present, most are based on the 'step-and-repeat' nanoimprint technique, which employs a small-area stamp, much smaller than the substrate. This is mainly because, when a large-area stamp is used, it is difficult to obtain acceptable uniform residual layer thickness and/or to avoid defects such as air entrapment. As an attempt to enable UV_NIL with a large-area stamp for high throughput, we propose a new UV-NIL tool that is able to imprint 4 inch wafer in a low vacuum environment at a single step.

• 대한공간정보학회지
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• 제8권1호
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• pp.13-25
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• 2000

도로교통환경문제는 현대의 도시생활에 있어서 세계공통의 심각한 환경문제의 하나이다. 본 연구에서는 도로교통환경문제, 특히 도로교통에 기인하는 대기오염문제의 평가를 위한 지원시스템을 개발하였다. 본 개발시스템은 GIS, 교통관련의 대기오염시뮬레이션모델, 예비적 대책들의 데이타베이스로 구성되어 있다. 대기오염시뮬레이션모델의 구축에 있어서, GIS지원환경은 연구대상지역의 대량의 공간정보의 처리와 실제위치상에서의 보다 정확한 대기오염의 계산이라는 점에서 유용한 툴(tool)을 제공할 수 있다. GIS지원시스템의 이러한 역할은 보다 효율적인 분석과 보다 합리적인 결정을 위하여 매우 유용한 것이다. 본 연구에서 개발된 시스템의 실용성은 이집트 카이로시의 도시권을 연구대상지역으로 적용함으로써 그 가능성을 확인할 수 있었다.

• 한국항공운항학회지
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• 제26권3호
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• pp.23-31
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• 2018

This paper describes the effect of advice information for arriving aircraft landing order on the air traffic controller's work efficiency. The air traffic control simulator used in the experiment was modeled on the basis of the aircraft parameters from BADA, gamma-command model and the 4-dimensional trajectory using the Bezier curve. The simulation results show that advice information was helpful for the performance of the work for users who did not have the air traffic control training. On the other hand, in case of users who have experience in air traffic control training, the work efficiency was lowered when the advisory information that does not reflect the user's intention is provided. Therefore, it can be seen that the effect of improving the work efficiency through advice information can be limited depending on the skill level of the air traffic controllers and the complexity of the air traffic situation.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.348-353
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• 2006

Autonomous and intelligent resource model (AIR-model) defines a building-block of complex systems to pursue value creation by means of diverse resources, referred to as an AIR-unit, and presents a collaboration model with the AIR-units. An AIR-unit represents a piece of resources, such as machines, labor, raw materials, and other assets, considered individually by a complex system as means to accomplish given tasks. It is defined with its own service capability and a goal, and pursues achieving the goal by means of the capability. Moreover, an Air-unit is equipped with autonomy and intelligence, whereby it makes a decision on its course of action on its own initiative. Air-units collaborate on system operations with each other through goal-oriented negotiations. In this research, distinctive features of the AIR-model are addressed and described in detail. Principal components of the AIR-model are also designed via object-oriented modeling techniques. A prototype system based on the AIR-model is finally presented as an embodiment tool of a fractal manufacturing system (FrMS).

• 한국정밀공학회지
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• 제11권1호
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• pp.123-128
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• 1994

A high speed spindle system for machine tools can be used to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials, and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices, cooling jacket and so on. And an air cooling experiment for evaluating the performance of the spindle system is carried out. Especially, in ofder to establish the air cooling conditions related to the development of a high speed spindle system, the effects of cooling air pressure, oil supply rate, air supply rate and rotational spindle speed are studied and discussed on the bearing temperature rise and frictional torque. Also the effects of cooling air pressure, rotational spindle speed and spindle system structure is investigated on the bearing temperature distribution. The experiment on the test model reveals the usefulness of the air cooling method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.143-144
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• 2007

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.48-52
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• 2004

Ultrasonic machining is effective for machining of extreme hard and brittle materials, including glass, ceramic, carbide, graphite. The major machining principle involves the direct hammering as well as the impact of abrasive panicles on the workpiece. Also, it involve cavitation erosion. The general workpiece is flat side. This study attempted micro hole machining of a curved surface of glass tube. Ultrasonic machining is fault of the slow machining speed. An experiment does and got 16 seconds validity machining time as increasing the processing speed. Moreover, entrance crack and surface roughness was similar both machining speed is slow and fast. Several micro hole of glass tube machined using one micro tool, but tool wear is infinitesimal.

• 한국정밀공학회지
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• 제17권4호
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• pp.129-134
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• 2000

This paper presents the development of ultra-precision machining process of large aspheric aluminum mirrors with a maximum diameter of 620 mm. An ultra-precision machine, "Nanoturn60", developed by Daewoo Heavy Industries Ltd. is used for machining and motion errors of the machine are compensated by using the FTS developed by IAE(Institue for Advanced Engineering) during the machining process. To check the form accuracy of machined aspheric surfaces, on-machine form measurement system is developed. This measurement system consists of air bearing touch probe, straight edge, and laser sensor. With in-process error compensation by FTS(Fast Tool Servo), aspheric mirrors with the from accuracy of submicron order are obtained. obtained.