• 한국의상디자인학회지
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• 제8권1호
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• pp.69-79
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• 2006

The purpose of this study is to find the proper width of fabric which can bring high efficiency on productivity. We focus on the marking method by comparing and analyzing the marking efficiency of A-line skirt. This study employs 4 criteria to mark the A-line skirt, which are cutting method, angle, width, and direction, respectively. There can be 2 different cutting methods(fold pattern and add seam pattern at the front and back center line), and 2 different angles(warp angle and bias angle). Also, width of the fabric can be classified into 2 groups(110cm, 150cm), and marking direction can be grouped into 2(one direction marker and one direction per each size marker). These 4 criteria make 16($2^*2^*2^*2$) cases for this study. Main findings are follows. First, the skirt with folded at the center line had higher efficiency rate than the skirt with add seam at the center line. Second, the skirt with the 150cm width has higher efficiency rate than that of 110cm. Third, fixing the warp angle has higher efficiency rate than that of fixing the bias angle at the front and back center line. Finally, one direction per each size marker has much higher efficiency than the one direction marker.

• 복식문화연구
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• 제14권2호
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• pp.286-298
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• 2006

The purpose of this study is to find the proper width of fabric which can bring high efficiency on productivity. We focus on the marking method by comparing and analyzing the marking efficiency of flare skirt. This study employs 4 criteria to mark the flare skirt, which are angle, location, width, and direction, respectively. There can be 3 different angles$(180^{\circ},\;270^{\circ},\;360^{\circ})$, and 2 different locations(the center line and the middle of the pattern) according to fixing of the warp line of the fabric. Also, width can be classified into 2 groups(110cm, 150cm), and marking direction can be grouped into 2(one direction marker and one direction per each size marker). These 4 criteria make $24(3{\times}2{\times}2{\times}2)$ cases for this study. Main findings are follows. Fist, the skirt with the 150cm width has higher efficiency rate than that of 110cm. Second, fixing the warp line at the center line has higher efficiency rate than that in the middle. Finally, per size marker has much higher efficiency than the just direction marker. In sum, we find that 150cm width with the center warp line and per size marker brings the highest efficiency rate.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.38-39
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• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.473-478
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• 2005

최근의 컨테이너물동량 증가는 선사간 경쟁의 심화를 유발하였고 이는 개별 선사들의 채산성 악화를 초래하였다. 따라서 운항선사들은 노선에 투입되는 자사 선박들에 대해서 운항효율성을 분석하고 대응방안을 강구할 필요성이 대두되고 있다. 이러한 배경에서 출발한 본 연구는 선사측면에서의 운항효율성을 분석하고 도출된 결과를 바탕으로 효율성을 향상시킬 수 있는 방안을 제시하고자 한다. 효율성분석을 하기 위해서 본 연구에서는, 운항선사의 실제 운항자료를 바탕으로 항차를 의사결정단위로 하여 비교적 객관적이고 상대적인 효율성을 파악할 수 있는 DEA모형을 이용하여 분석을 수행하였다. 그리고 효율성 분석결과를 바탕으로 운항선사의 운영측면에서 전체적인 효율성을 높이는 방안을 모색해 보고자 한다.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.61-66
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• 2013

In this paper, a control scheme with the capability of high efficiency, which is realized by predicting the conditions of a load power and an input power, is proposed for the uninterruptible power supply (UPS). Generally, on-line UPS system supplies a constant voltage and a constant frequency (CVCF). However, the efficiency of the On-line UPS system can be reduced due to the switching losses of semiconductor devices during the power conversion. The these losses are improved by the proposed smart UPS with the high efficiency drive system, which is realized by analysing and predicting the conditions of a load power and an input power.

• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.618-627
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• 2005

In this paper, we have compared and analyzed the performance of high amplifier using Doherty technique to improve linearity and efficiency of base station and repeater Power amplifier for WCDMA. This Doherty amplifier implements with 3dB branch line coupler and $90^{\circ}C$ transmission line The phase offset line is designed to maintain the high linearity and efficiency at the low efficiency Period of the power amplifier CW 1-tone experimental results at the WCDMA frequency $2.11{\sim}2.17GHz$ shows that Doherty amplifier which achieves power add efficiency(PAE) of 50% at 6dB back off the point from maximum output power 52.3 dBm, obtains higher efficiency of 13.3% than class AB Finding optimum bias Point after adjusted gate voltage, Doherty amplifier shows that $IMD_3$ improves 4dB.

• 산업경영시스템학회지
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• 제18권36호
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• pp.297-306
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• 1995

An automatic transfer line consists of several stages(groups of stations) in series into one system by a common transfer mechanism and a common control system. In this system losses of the efficiency are evidenced in periods where a stage is forcod down- starved or blocked. The efficiency of an automatic transfer line can be improved by providing buffer storages between a stage or the length of line common senses there are several critical factors, system configurations relative position, and buffer capacity allocations in automatic transfer line are considered with a point of view production rates, average stock, and mean delay. The propose of this paper is to provide the robust designs by Taguchi method which improve the efficiency of four-stage transfer line.

• 한국항해항만학회지
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• 제29권6호
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• pp.495-500
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• 2005

최근 컨테이너물동량 증가로 인하여 선사들간의 경쟁이 심화되고 있다. 따라서 운항선사들은 노선에 투입되는 자사 선박들에 대해서 운항효율성을 분석하고 대응방안을 강구할 필요성이 대두되고 있다. 이러한 배경에서 출발한 본 연구는 선사 입장에서의 내부적 운항효율성을 분석하고 도출된 결과를 바탕으로 효율성을 향상시킬 수 있는 방안을 제시하고자한다. 효율성분석을 하기 위해서 본 연구에서는. 운항선사의 실제 운항자료를 바탕으로 항차를 의사결정단위로 하여 비교적 객관적이고 상대적인 효율성을 파악할 수 있는 DEA모형을 이용하여 분석을 수행하었다. 그리고 효율성 분석결과를 바탕으로 운항선사의 운영측면에서 전체적인 효율성을 높이는 방안을 모색해 보고자 하였다.

• 한국위성정보통신학회논문지
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• 제12권4호
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• pp.146-151
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• 2017

본 논문은 전력선 통신 시스템에서 에너지 효율을 최적화하기 위해 송신 전력 및 부 채널 할당을 최적화하는 에너지 효율적인 자원 할당 알고리즘을 제안하였다. 제안한 알고리즘은 특히 수신기에 최대의 신호 전력을 전달하기 위해서 기존의 연구와 다르게 주파수에 따라 변하는 전력선 채널의 특성을 시스템 모델에서 고려하였다. 또한, 에너지 효율 함수를 최대화 할 때 송신기의 최대 신호전력 한계 및 최소 데이터 전송률 만족 등 현실적인 제한조건들을 고려하여 전송 알고리즘을 설계하였다. 따라서 본 논문에서는 비선형 분수 프로그래밍과 라그랑지 이중 기법을 이용하여 최적값을 산출하였고 시뮬레이션을 통해 베이스라인 기법 대비 제안한 알고리즘의 에너지 효율 성능의 우수성을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.94-99
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• 2011

EMU(Electric Multiple Unit) of Seoul Metro are equipped with air conditioning and six line flow fans for air circulation. In summer, the air conditioning and line flow fans usually work at the same time. Recently, high oil price leads more people to use public transportation, which in turn makes them feel hotter inside the rolling stocks and complain about air conditioning state. In order to improve indoor air quality in summer, it is inevitable to increase the cooling capacity of air conditioners, which costs a lot of money. Thus, we need to raise cooling efficiency by rearranging existing devices effectively. In this study, we found a better way to improve refreshment inside the trains by changing the operation method of line flow fans and door opening systems. The results will help improve the cooling efficiency of EMU in summer. Also, more precise experiments and analyses of our data can lead to various methods to increase energy efficiency.