• 대한조선학회논문집
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• 제60권2호
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• pp.95-109
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• 2023

In the 4th industrial revolution, changes in the technological paradigm have had a direct impact on the maintenance system of ships. The 2-stroke low speed engine system integrates with the core equipment required for propulsive power. The Condition Based Management (CBM) is defined as a technology that predictive maintenance methods in existing calender-based or running time based maintenance systems by monitoring the condition of machinery and diagnosis/prognosis failures. In this study, we have established a framework for CBM technology development on our own, and are engaged in engineering-based failure analysis, data development and management, data feature analysis and pre-processing, and verified the reliability of failure mode DB using LSTM algorithms. We developed various simulated failure mode scenarios for 2-stroke low speed engine and researched to produce data on onshore basis test_beds. The analysis and pre-processing of normal and abnormal status data acquired through failure mode simulation experiment used various Exploratory Data Analysis (EDA) techniques to feature extract not only data on the performance and efficiency of 2-stroke low speed engine but also key feature data using multivariate statistical analysis. In addition, by developing an LSTM classification algorithm, we tried to verify the reliability of various failure mode data with time-series characteristics.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.78-85
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• 2013

This paper presents the sliding mode control methods for anti-lock brake system (ABS) with the friction force observer. Using a simplified quarter car model, the sliding mode controller for ABS is designed to track the desired wheel slip ratio. Here, new method to find the desired wheel slip ratio which produces the maximum friction force between road and tire is suggested. The desired wheel slip ratio is varying according road and tire conditions to produce maximum friction force. In order to find optimum desired wheel slip ratio, the sliding mode observer for friction force is used. The proposed sliding mode controller with observer is evaluated in simulation, and the control design is shown to have high performance on roads with constant and varying adhesion coefficients.

• 수산해양기술연구
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• 제40권2호
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• pp.138-143
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• 2004

제주대학교 실습선 아라호에 정착된 능동형 횡동요 감쇠장치의 성능에 관해 연구하기 위하여 33$^{\circ}$00‘.44”N, 125$^{\circ}$59’.88 ”E 위치에서 선박을 정지한 후, 횡동요 감쇠장치를 정지 (Passive A.R.T), 작동 (Active A.R.T)을 했을 때 경사계에 의한 횡동요각 및 종동요각, 풍속계에 의한 풍속의 변화와 그리고 선박이 항해 중에 감쇠장치의 작동을 정지(Passive A.R.T), 작동(Active A.R.T) 했을 때 의 능동형 횡동요 감쇠장치의 성능을 분석한 결과에 대해 요약하면 다음과 같다. 1. 선박이 정지했을 때 횡동요 감쇠장치를 정지, 작동한 경우 횡동요각의 평균진폭 (Average Amplitude of Roll) 은 각각 8.30$^{\circ}$, 4.37$^{\circ}$, 횡동요각의 유의진폭(Significant Amplitude of Roll $_{{\pi}{1/3}}$)은 각각 10.10$^{\circ}$, 5.30$^{\circ}$으로 나타났다. 2. 선박이 항해 중 일 때에는 횡동요각의 평균진폭 (Average Amplitude of Roll)은 각각 5.01$^{\circ}$, 4.36$^{\circ}$, 횡동요각의 유의진폭 (Significant Amplitude of Roll$^{\circ}$) 은 각각 5.50$^{\circ}$, 5.10$^{\circ}$으로 각각 나타났다. 3. 횡동요 감쇠장치는 선박이 정치했을 때에는 47.5%, 선박이 운항 했을 때는 12.7% 정도의 감쇠 효율을 보여서 정지했을 때 그 효율이 높은 것으로 나타났다. 4. 횡동요 감쇠 장치는 종동요(Pitching)에 대해서는 거의 영향을 미치지 않았다.

• 시스템엔지니어링학술지
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• 제18권1호
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• pp.46-57
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• 2022

In this paper, we proposed the DFMEA Implementation Method for safety design of Weapon System. First, we presented the process for DFMEA. And then, the case analysis of OOO missile was performed in accordance with the process presented. After defining the system requirements of OOO missile, failure definition scoring criteria was set. In order to clarify the definition of failure, the failure was classified into safety, reliability, maintainability and others. After performing the function analysis, the relationship matrix analysis was performed to identify the failure mode according to the function without omission. After clarifying the failure classification, mode of failure, cause of failure and effect were analyzed to calculate the severity, occurrence and detection values. After the action priority was judged, the recommended action according to the failure classification was identified for the determined action priority. The results of this study can be used as a relevant basis for the design reflection and resource re-allocation of stakeholders.

• 설비공학논문집
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• 제21권5호
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• pp.297-304
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• 2009

The aim of this study is to investigate the cooling performance of ground source multi-heat pump systems with a vertical single U-tube GLHX(U-tube system) and a vertical double tube GLHX(double tube system), which were installed in a school building located in Cheonan. All systems were operated in a part load conditions for all day, and the maximum COP of the single U-tube system and the double tube system were 6.2 and 5.2 at cooling mode, respectively. The double tube GLHX designed by the GLHEPRO, commercial program, was estimated to have the same performance as the U-tube GLHX, because the inlet temperatures of each outdoor unit heat exchanger for the former was similar to the latter. However, it is needed to prove the long tenn performance. It is suggested that the new algorithms to control the flow rate of secondary fluid for GLHX according to load variation have to be developed in order to enhance the performance of the system.

• 동력기계공학회지
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• 제21권4호
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• pp.57-61
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• 2017

The vehicle label fuel economy is used as an energy management indicator nationwide. It induces technology development of automobile manufacturers and plays a role of providing information when purchasing a consumer vehicle. However, consumers who purchase a new vehicle continued to complain that the label fuel economy is different from the mandatory fuel economy rate. The domestic fuel economy measurement method is the same as the North American measurement method. The results of the two test modes (urban (FTP-75 mode), highway (HWFET mode)) are calculated in five test modes reflecting various environmental conditions and driving patterns 5-cycle correction formula is used which is equivalent to the fuel efficiency value. In this study, to solve the consumers' curiosity about the fuel economy of new vehicle, we use domestic fuel economy measurement method to measure the new car condition within 150 km of driving distance and the cumulative driving distance condition of domestic label fuel economy test vehicle. A comparative evaluation of fuel economy was carried out for a durability vehicle of $6,500{\pm}1,000km$. A result, mean value of the fuel economy of the four gasoline vehicles increased by 2.7 % in the city center mode and by 2.5 % in the highway mode in the durable vehicle compared new vehicle. And in the case of the diesel vehicle it increased by 2.5 % and 3.9 % respectively. The harmful exhaust gas emitted from the vehicle also resulted in more emissions of both gasoline and diesel vehicles in new vehicles. It is considered that the increase of the frictional force of the vehicle driving system and the lubricating oil system would have an effect on the reduction of the fuel economy of the new vehicle, and it was found that the fuel economy and the exhaust gas were improved by proper cumulative distance (domesticate) to the new vehicle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.249-251
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• 1994

This paper introduces an implementation of high performance voltage source inverter system based on 16bit micro-processor and DSP for the application to modem rolling stock traction system. In contrast with other industry oriented inverter system, this system requires precise control action complying with various load condition and high overload capability. An asynchronous PWM generation and 3' pulse mode technology are adopted in order to improve compliant starting torque characteristics at starting phase and soft backward-forward starting motion.

• 설비공학논문집
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• 제16권4호
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• pp.340-348
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• 2004

The air and refrigerant side heat transfer performances are key parameters to improve heat transfer efficiency of the heat exchanger including the fan performance. Design of the fins, treatment of the tube inside, tube diameter and tube array effect heat transfer performance of the heat exchanger. The heat exchanger is used as a condenser at cooling mode and used as an evaporator at heating mode in the heat pump system. The heat pump system uses R410A as the refrigerant. The heat exchangers are consisted with 7 mm diameter tubes with slit-type fins. The study was conducted with variation of arrangement of the refrigerant path and air flow rate and refrigerant pressure drop and heat transfer rate were measured with a code tester. The capacity of the 3 path heat exchanger is more efficient than 2 or 4 path heat exchangers in heating or cooling modes.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.523-526
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• 2010

FM 무전기는 반이중통신(Half-duplex)방식을 사용한다, FM 무전기를 DCE(Data Circuitterminating Equipment)로 사용하고 다수의 가입자가 정보교환을 수행하는 통신망에서 데이터 전송이 일어나고 있는지를 검출하고 데이터 전송 시 충돌을 방지하기 위해 Network Access Control을 사용한다. 본 논문에서는 현재 우리 군에서 운용하고 있는 FM무전기를 사용하는 통신망에서 MIL-STD-188-220C의 Network Access Control 방법 중 R-NAD(Random Network Access Delay)를 적용한 MPC8260 Power QUICC 기반의 디지털 메시지 전송장비에 대하여 연구한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.21-26
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• 2008

Recently, small and medium-sized buildings have employed a multi-heat pump. The major benefits of the multi-heat pump over a conventional system are that it is easier system to maintain along with a diversification of facility use, and high comfortability. The performance of multi-heat pump systems can be enhanced by using geothermal energy instead of air source energy. This paper describes the multi-heat pumps applied in an ground source heat pump system for an actual building. The performance of a ground source multi-heat pump installed in the field was investigated in cooling mode. The maximum COP of the systems with single U-tube and double tube ground loop heat exchangers were 6.6 and 6.0, respectively. It is suggested that the new algorithms to control the flow rate of secondary fluid for ground loop heat exchanger have to be developed in order to enhance the performance of the system.