• 한국화재소방학회논문지
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• 제15권4호
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• pp.49-56
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• 2001

화재시 특별피난계단의 부속실의 연기침입을 방지하기 위해 적용하고 있는 급기가압방연시스템의 효능에 대한 논란이 증가하고 있는 바, 국내 고층 건축물의 특별피난계단에 설치운용중인 급기가압시스템의 설계시 핵심요소인 가압공간의 누설틈새, 계단실과 부속실 또는 부속실과 거실공간사이의 출입문을 통한 방연풍속과 출입문의 자동폐쇄를 보장하는 도어 개폐장치등에 대한 문제점을 조사연구하여 실질적인 효과를 보장할 수 있는 기준을 설정하고, 안전성확보를 보장하면서 경제성을 고려한 설계안을 세부적인 사례를 들어 구체적으로 제시하였다.

• 제어로봇시스템학회논문지
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• 제10권3호
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• pp.286-293
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• 2004

This paper presents the result of a study on the starter control for a turbo generator. Because a starter in gear box type turbo-generator system is composed of gearbox and brush DC motor, it should be replaced with High Speed Generator(HSG)) in HSG type Turbo-generator. There-ore, it is necessary to design a new starting algorithm and starter. In gearbox type system, brush DC motor is rotated to the designed speed using low voltage-high current battery power. After brush DC motor speed is increased to several times by gearbox, gas turbine engine can be rotated to designed starting speed. If we implement a starter with High Speed Generator(HSG), it is necessary to drive high-speed generator to high-speed motor. High-speed generator with permanent magnet on rotor has a low leakage inductance fur driving high-speed rotation, and it is necessary high DC link voltage for inverter when High-speed generator is driven to high speed. This paper presents result of development of the boost converter for converting high voltage DC from low battery voltage and design of the inverter for controlling a high frequency current to be injected to motor winding. Also, we show performance of the designed starter by driving the turbo generator.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1495-1502
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• 2017

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

• KSTLE International Journal
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• 제1권2호
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• pp.113-117
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• 2000

The rotary-vane compressor has become one of the most successful types of compressors because of its mechanical reliability, compactness, and adaptability to moderately high-speed operation in virtually an unlimited range of sizes. However recently, the depletion of the ozone layer due to the current refrigerant(R22) has been getting worse, and it is one of the world's pressing issues. In this paper, we will discuss the use of R410a in the compressor of a room air-conditioner as an alternative refrigerant and air-conditioning system to R22, since R410a has greater refrigerant characteristics than R22. Miniaturization of the rotary compressor for the new refrigerant and air-conditioning system is also possible, which reduces the prime cost of production, hence R410a is naturally a better refrigerant. But to apply the new HFC refrigerant system in refrigeration and air-conditioning systems, a significant redesign of the current refrigerant system is also required, because as the refrigeration changes, lubrication characteristics vary. Close attention must be paid to friction force and energy loss due to friction and wear at many sliding areas.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.226-231
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• 2011

This study set out to review the air current fluidity in exhaust common ducts by installing an inlet pipe at a leisure space in the PS(Pipe Shaft)room for the sake of wind power generation with kitchen and bathroom exhaust common ducts of all the equipment and air conditioning shafts in high-rise apartment. The air current functionality of kitchen and bathroom exhaust common ducts was reviewed by analyzing wind velocity changes according to changes to the area of exhaust common ducts through a simulation, changes to the wind velocity of the kitchen hood by applying an external inlet pipe, changes to the usage factor of exhaust common ducts, and changes to wind velocity by altering the form of the ventilator at the bottom of the old exhaust common duct. It was a basic study on the utilization of exhaust wind velocity in exhaust common ducts.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.612-615
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• 2013

허브(hub) BLDC(Brushless Direct Current) 전동기란 아우터로터 타입 고효율 전동기로 다극의 영구자석으로 이루어진 회전자가 바퀴의 구동축이 되는 직접구동용 모터를 말하며, 휠인모터라고도 불린다. 본 연구에서는 허브모터를 구동축으로 갖는 2륜 또는 3륜 구동체를 구동하기 위한 BLDC 허브모터 속도 제어기를 PIC 마이크로 컨트롤러를 이용하여 설계한다. 구동기는 6 개의 독립된 MOSFET 스위칭소자를 사용하여 구성하며, 게이트 구동회로는 직접 설계하여 경제성을 높인다.

• Journal of Power Electronics
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• 제14권5호
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• pp.957-966
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• 2014

Some of DC actuators used in home automation, office automation, medical equipment and automotive systems require a position sensor. In low power applications, the introduction of such a transducer remarkably increases the whole system cost, which justifies the development of sensorless position estimation techniques. The well-known AC motor drive sensorless techniques exploiting the fundamental component of the back electromotive force cannot be used on DC motor drives. In addition, the sophisticated approaches based on current or voltage signal injection cannot be used. Therefore, an effective and inexpensive sensorless position estimation technique suitable for DC motors is presented in this paper. This technique exploits the periodic pulses of the armature current caused by commutation. It is based on a simple pulse counting algorithm, suitable for coping with the rather large variability of the pulse frequency and it leads to the realization of a sensorless position control system for low cost, medium performance systems, like those in the field of automotive applications.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.380-383
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• 2014

허브(hub) BLDC(Brushless Direct Current) 전동기란 아우터로터 타입 고효율 전동기로 다극의 영구자석으로 이루어진 회전자가 바퀴의 구동축이 되는 직접구동용 모터를 말하며, 휠인 모터로도 불린다. 본 연구에서는 BLDC 허브 모터 구동을 위한 벡터제어 기법 속도 제어기를 dsPIC30f2010 16비트 마이크로 컨트롤러를 이용하여 설계한다. 특히 복잡한 연산 시간을 줄이는 벡터 제어 방법을 제안하고, MOSFET 인버터 구동기를 직접 설계하여 경제성을 높인다.

• Tribology and Lubricants
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• 제34권5호
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• pp.169-174
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• 2018

A multi-stage compressor (MSC) is comprised of several impellers installed in the pinion gear shaft driven by a main bull gear. In the pinion shaft, a thrust collar (TC) is installed to support the thrust load. The TC makes the lubrication system simpler in the MSC; therefore, it is widely used in similar kinds of machinery. Typically, TCs are installed on both sides of the bull gear and pressure is developed in the lubricated area by creating a taper angle on the TC and bull gear surface. In the current study, we developed a numerical analysis model to evaluate the performance of the TC considering its design parameters. We sloved the Reynolds equation using the finite element method and applied the half Sommerfeld condition to consider cavitation. Based on the pressure calculated in the lubricated area, we calculated the power loss and minimum film thickness. In addition, we calculated stiffness and damping using perturbation method. We performed parametric studies using the developed model. The results of the analysis show that the maximum pressure presents in the center area of the TC and it increases with the taper angle. The area over which pressure is developed decreases with the taper angle. The results also show that there is an optimum taper angle providing minimum power loss and maximum film thickness. Additionally, the stiffness and damping decrease with the taper angle. As the applied load increases, the power loss increases and the minimum film thickness decreases. However, the stiffness and damping increase with the applied load.

• 대한기계학회논문집A
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• 제21권12호
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• pp.1984-1991
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• 1997

Recently burr technology is rising in the fields of the precision manufacturing and the high quality machining, deburring has treated as a difficult problem on going to the high efficiency, automation in the FMS. Removal of burr with various shapes, dimensions and properties couldn't be standardized and has depended on manual treatment. Especially, deburring for cross hole inside owing to passing through out perpendicular to a main hole is more difficult, the electrochemical method is proper as its solution at practical aspects. Burr elimination in the cross hole drilling of governor shaft used in the automobile engine so far has been worked by a manual post-processing by a skillful worker, which becomes a factor of productivity-down and cost-up so that improvement of machining process is needed. Therefore, for the high efficiency and automation of internal deburring in the cross hole, development of electrochemical deburring technology is needed. So, the new process in the burr treatment is supposed. In this study, characteristics of electrochemical deburring through experiments were identified and factors such as electrolytic gap and electorlytic fluid contributed to removal burr height were analyzed. Also, deburring efficiency and electrolytic performance for cross hole were examined according to electrolytic current and electrochemical deburring condition corresponding to acquired edge quality was found out.