• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.79-86
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• 2002

As consumer electronics, information, and aero-space industry grow, the demand for aspheric lens increases higher. To enhance the precision and productivity of aspheric surface, a CAM system for ultra-precision aspheric surface needs to be realized. In this study, the developed CAM system can generate NC code fur various aspheric surfaces fast and precisely by a new bi-arc interpolation method that the location of maximum error is fixed at an efficient point. The newly developed bi-arc meets the given tolerance more precisely, performs faster calculation. The cutting condition input module and the NC code verification module are adequate to ultra-precision machining, so that a operator can obtain products fast and easily.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.1
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• pp.53-59
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• 2014

In multiple object tracking, accurate detection for each of objects that appear sequentially and effective tracking in complicated cases that they are overlapped with each other are very important. In this paper, we propose a multiple object tracking system that has a concrete detection and tracking characteristics by using multi-lateral histogram and SIFT feature extraction algorithm. Especially, by limiting the matching area to object's inside and by utilizing the location informations in the keypoint matching process of SIFT algorithm, we advanced the tracking performance for multiple objects. Based on the experimental results, we found that the proposed tracking system has a robust tracking operation in the complicated environments that multiple objects are frequently overlapped in various of directions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.534-537
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• 1996

As consumer electronics, information, and aero-space industry grow, the demand for aspheric lens increases higher. To enhance the precision and productivity of aspheric surface, a CAM system for ultra-precision aspheric surface needs to be realized. In this study, the developed CAM system can generate NC code for various aspheric surfaces fast and precisely by Tri-arc interpolation method that the location of maximum error is fixed. The cutting condition input module and the NC code verification module are adequate to ultra-precision machining, so that a operator can obtain products fast and easily.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.470-477
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• 2022

EOTS for drones is showing another aspect of market expansion in detection and recognition areas previously occupied by artificial satellites. The two-axis EOTS for drones controls the vibration or disturbance caused by the drone during the mission so that EOTS can accurately recognize the goal. Vibration generated by drones is transmitted to EOTS. Therefore, it is essential to develop a stabilization controller that attenuates vibrations transmitted from drones so that EOTS can maintain the viewing angle. Therefore, it is necessary to standardize drone disturbance and secure the performance of EOTS disturbance attenuation controller optimized for disturbance level through this. In this paper, a method of standardizing drone disturbance applied to EOTS is studied, through which EOTS controller simulation is performed and stabilization controller shape is selected and designed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.603-604
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• 2020

한국사회는 전통적인 대가족제도가 급속히 해체되고 저 출산 및 고령화로 인한 고령층의 1인 가정의 수가 급속히 증가하고 있는 추세이다. 고령자 1인 가구에 대한 다양한 서비스와 고도화가 필요한 이유이다. 본 연구에서는 1인 가정을 대상으로 IoT 기기를 통한 다양한 PHR 생체 신호와 환경정보을 수집하고 수집된 정보를 바탕으로 건강상태를 모니터링하는 시스템을 제안한다. 제안하는 시스템은 의료기기에서 제공되는 개방형 PHR 데이터의 융합으로 정보 분석 및 예측능력을 강화하고 고독사 상황파악 및 방지 프로그램을 이행할 수 있는 기본 인프라을 구축하고자 한다. 또한 중장년층의 미래에 대한 불확실성을 제거하고 사회복지서비스의 확대를 위한 정책적 과제의 논의적 목적을 가지고 있다. 본 연구의 결과물은 사회 소외 계층에 대한 서비스 확대와 국민의 의료환경 개선에 도움이 될 것으로 사료된다.

• Tribology and Lubricants
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• v.25 no.2
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• pp.108-113
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• 2009

This paper presents a experimental results for the performance evaluation of a double-bumped air foil bearing. The test results of a double-bumped AFB is compared with a single-bumped AFB at a heavily-loaded condition. The diameter of the test bearing is 50 mm, and the axial length is 50 mm. Nominal clearance of the single-bumped AFB is evaluated as $105{\mu}m$, and that of the double-bumped AFB is as $95{\mu}m$. The test of the AFBs are demonstrated at 3 test mode; the load variation mode, the speed variation mode, and start-stop mode. The single-bumped AFB demonstrated a upward load-carrying capacity of 95 N and a downward load-carrying capacity of 130 N at 20,000 rpm. The double-bumped AFB demonstrated a upward load-carrying capacity of 170 N and a downward load-carrying capacity of 170 N at 20,000 rpm. The single-bumped AFB demonstrated a downward lift-off speed of 16,300 rpm at 105 N. The double-bumped AFB demonstrated a downward lift-off speed of 15,400 rpm at 105 N. The start-stop test of the AFBs assure 5,000 cycle endurance life. The test results are compared with the theoretical calculation results. The test and theorectical results show thata double-bump air foil bearing provides a higher load-carrying capacity, stiffness and damping than a single-bump air foil bearing in a heavily-loaded condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.270-276
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• 2019

According to the International Maritime Organization (IMO) 2020 Regulation, ships operating outside designated emission control areas (ECA) have to use low-sulfur oil with a sulfur content of 0.5% or less by January 2020. To minimize the consumption of high-priced low-sulfur oil, it is urgent to introduce efficient energy-saving devices (ESD), and contra-rotating propeller (CRP) systems are well known to be the most effective one. The shafting system that drives a CRP is composed of an inner shaft and an outer one and has a mutually influential system that is much more complex and heavier than a general shafting system. An initial design was carried out to install a CRP system for the first time in Korea. The purpose of this study is to verify whether the journal bearing meets the classification's design criteria through a bearing reaction force analysis for the classification's approval of the initial design. It is ideal for the thrust of the propeller to act on the center of the shaft, but thrust eccentricity occurs due to the uneven wake caused by the stern shape. Load conditions were applied while considering thrust eccentricity to perform the shaft analysis, and the results were compared with the classification's criteria.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.30-37
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• 2005

Cycle simulation of Ground Source Heat Pump[GSHP] system was carried out to determine the design specification of basic components such as turbo compressor and heat exchangers. Part load operation characteristics of the designed GSHP system was estimated using the compressor and heat exchanger performance data. A 50RT class turbo compressor for GSHP system is now under development, in which R134a refrigerant is adopted as working fluid. The compressor with variable cascade diffusers is designed to work both in cooling and heating modes so that it can actively keep up with the climate change with high efficiency. The normal running speeds of the compressor are 59000rpm for heating mode and 70000rpm for tooling mode respectively. It has two identical impellers at both ends of the rotor so as to minimize aero-induced thrust force effectively. GSHP system was coupled with a vortical type heat exchanger, and heat gain and heat loss from ground were evaluated per a bore hole. For the optimal integration of the heat pump system, its header for circulating fluid was combined with the ground heat exchangers in parallel and series configuration.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.33-37
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• 2017

To protect the power systems from fault current, the rated protective equipment should be installed. However growth of power system scale and concentration of loads caused the large fault current in power transmission system and distribution system. The capacities of installed protective equipment have been exceeded the due to increase of fault current. This increase is not temporary phenomenon but will be steadily as long as the industry develops. The power system operator need a counter-measurement for safety, so superconducting fault current limiter (SFCL) has been received attention as effective solutions to reduce the fault current. For the above reasons various type SFCLs have been studied recently. In this paper, operation characteristics and power burden of trigger type SFCL is studied. The trigger type SFCL has been used for real system research in many countries. Another trigger type SFCL (double quench trigger type SFCL) is also studied. For this paper, short circuit test is performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.554-559
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• 2017

Recently, the global attention is focused on the development of the renewal aero-propulsion systems proved in the air pollution, the noise, the great operational cost, safety and risks. Especially, various study are conducting for the development of the advanced high power to weight ratio aircraft through the significant reduction of fuel consumption and upgrade of the propulsion efficiency, using the alternative propulsion system developments such as hydrogen and solar power system. The hybrid propulsion system can be the representative propulsion system which get the power sources by combining the merits of two or more power sources. In this study, the advancement trends, characteristics, design method which can be applied to the renewal future UAV development.