• Title/Summary/Keyword: cold start

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Development of Inverter for Improvement of Low Temperature Operation of LCD Backlight using Flat Fluorescent Lamp (FFL) (면광원을 이용한 LCD 백라이트의 저온구동특성 향상을 위한 인버터 개발)

  • Hur, Jeong-Wook;Lim, Sung-Kyoo
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.1
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    • pp.11-17
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    • 2007
  • The CCFLs, EEFLs and FFLs use mercury and the operating conditions are different at warm or cold temperature. At start of operation, there may exist a possibility of inhomogeneous operation of lamps or channels of FFL to the very low vapor pressure of mercury at low temperature. In this paper, an inverter with level control block (LCB) was developed to drive LCD backlight using FFL stably at low temperature range. The operation of FFL backlight at $-20^{\circ}C$ was successfully demonstrated by developing inverter with LCB under 130 Watt of power consumption.

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Study of High Altitude Operation for Air Swirl Injector in Tangential Swirl Combustor (Tangential Swirl 연소기에 적용된 스월인젝터의 고고도 운전성능 연구)

  • Park, Hee-Ho;Ryu, Se-Hyun;Koo, Hyun-Cheol;Lee, Seong-Jun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.825-828
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    • 2010
  • APU for aircraft is operated under severe condition as high altitude and low temperature, and demand high reliability in flight. This study is to be verified of the ignition and the combustion stability of APU under the harsh conditions. The basic data obtained in combustion rig test were directly applied to the altitude test with a engine. That start logic was obtained in ground development test. The results of altitude test show that air swirl injector has good operation and ignition performance at 20kft, hot/cold($-40^{\circ}C$) day.

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Improving Web Personalization Service Using Web Mining and Collaborative Filtering (웹 마이닝과 협력적 정보 여과를 이용한 개인화 서비스의 성능 개선 방안)

  • 이치훈;고세진;김용환;이필규
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.10b
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    • pp.63-65
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    • 2000
  • 웹 개인화 기술의 발달은 많은 업체들이 기존 고객의 유지와 신규 고객의 확보를 위한 수단을 제공하였다. 현재의 개인화 기술은 크게 내용 기반 그리고 협력적 정보 여과 방식에 기반한 기술로 나뉘어질 수 있다. 내용 기반 정보 여과 방식에 기반한 개인화 기술은 멀티미디어 정보로 표현된 대부분의 웹 오브젝트(페이지, 이미지, 동영상, 사운드, 상품 등)에는 적용하기 어렵고, 협력적 정보 여과방식은 Cold Start Problem과 단일 도메인내에서의 개인화 서비스만이 가능하다는 문제점이 있다. 본 논문에서는 협력적 정보 여과 방식과 데이터 마이닝 기술 중의 연관 규칙 생성 방법을 혼합한 웹 개인화 시스템을 제안한다. 다양한 멀티미디어 형태로 표현되는 웹 오브젝트의 내용 분석이 어려우므로, 각각의 오브젝트를 하나의 아이템으로 인식하고 개인화 서비스를 시도하는 협력적 정보 여과 방식을 채택하였다. 협력적 정보 여과의 결과로 발견된 도메인별 유사 사용자의 웹 오브젝트 사용 정보를 연관 규칙 생성 알고리즘에 적용하여 오브젝트간의 연관성을 발견한다. 발견된 오브젝트간의 연관성은 서로 다른 정보 도메인의 오브젝트가 현재 사용자에게 흥미있는 것인가를 예측할 수 있는 자료로서 사용될 수 있다. 협력적 정보 여과 방식에 의해 생성된 오브젝트의 선호도값과 오브젝트 연관성 정보를 비교하여 사용자에게 개인화된 웹 서비스를 제공한다.

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Development of Air Cutoff Valve for Improving Durability of Fuel Cell (연료전지 내구성능 향상을 위한 공기차단밸브 개발)

  • Park, Jeonghee;Lee, Changha;Kwon, Hyuckryul;Kim, Chimyung;Choi, Kyusung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.1
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    • pp.49-55
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    • 2015
  • In this study, among in various scenarios of the duration degradation of the fuel cell, countermeasures for the cathode carbon carrier oxidation and the deactivation of catalyst by hydrogen / air interface formation have been studied. so the system was applied to the air cutoff valve. In terms of the component, the cold start performance, electrical stability, the airtight performance were mainly designed and their performance was confirmed. And in terms of the system, the air electrode flow is blocked off, so the oxygen concentration drops when system is powered off, As a result, By reducing unit cell voltage which affect the durability of the fuel cell reached up to 0.8V, the improved durability of the fuel cell was confirmed.

Cross-Product Category User Profiling for E-Commerce Personalized Recommendation (전자상거래 개인화 추천을 위한 상품 카테고리 중립적 사용자 프로파일링)

  • Park, Soo-Hwan;Lee, Hong-Joo;Cho, Nam-Jae;Kim, Jong-Woo
    • Asia pacific journal of information systems
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    • v.16 no.3
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    • pp.159-176
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    • 2006
  • Collaborative filtering is one of the popular techniques for personalized recommendation in e-commerce. In collaborative filtering, user profiles are usually managed per product category in order to reduce data sparsity. Product diversification of Internet storefronts and multiple product category sales of e-commerce portals require cross-product category usage of user profiles in order to overcome the cold start problem of collaborative filtering. In this paper, we study the feasibility of cross-product category usage of user profiles, and suggest a method to improve recommendation performance of cross-product category user profiling. First, we investigate whether user profiles on a product category can be used to recommend products in other product categories. Furthermore, a way of utilizing user profiles selectively is suggested to increase recommendation performance of cross-product category user profiling. The feasibility of cross-product category user profiling and the usefulness of the proposed method are tested with real click stream data of an Internet storefront which sells multiple product categories including books, music CDs, and DVDs. The experiment results show that user profiles on a product category can be used to recommend products in other product categories. Also, the selective usage of user profiles based on correlations between subcategories of two product categories provides better performance than the whole usage of user profiles.

Freeze/Thaw cycle effects on GDLs and MEAs of PEFC (동결/해동 열사이클이 PEFC의 GDL/MEA에 미치는 영향)

  • Lim, Nam-Yun;Park, Gu-Gon;Park, Jin-Soo;Yoon, Young-Gi;Lee, Won-Yong;Lim, Tae-Won;Kim, Chang-Soo
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.96-98
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    • 2006
  • Proper water management is vital to achieve high performance and durability of PEFC (Polymer Electrolyte Fuel Cell). The effects of the residual water from PEFC after purge in shut-down processes on GDL/MEAs were investigated with freeze/thaw cycles Freeze/thaw cycle tests were conducted with single cells which were designed from transparent acryl plates. Single cells which contain several amount of residual water were cycles from $80^{\circ}C$ to $-28^{\circ}C$. The resistance changes of the single cells which have various amount of residual water were evaluated by ac-impedance analysis with 24 times of freeze/thaw cycles. Also, after the freeze/thaw cycles, the property changes were characterized by visual methods such as SEM, EPMA. Though it was difficult to observe noticeable property changes in the visual characterizations, the resistance of cells dramatically increased with the amount of remained water.

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A Study on the Change of Heavy Snow Strength by SST in Influence of Continental Polar Air Mass

  • Park, Geon-Young;Ryu, Chan-Su
    • Journal of Integrative Natural Science
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    • v.7 no.1
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    • pp.39-44
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    • 2014
  • The results of the synoptic meteorological analysis showed that when the cold and dry continental high pressure was extended, heavy snow occurred at dawn when the upper atmosphere cooled. In particular, when the continental high pressure was extended and the upper pressure trough passed through, heavy snow occurred due to the convergence region formed in the west coast area, sometimes in the inland of the Honam area. In addition, it was verified that the changes in the humidity coefficients in the upper and lower layers are important data for the determination of the probability, start/end and intensity of heavy snow. However, when the area was influenced by the middle-latitude low pressure, the heavy snow was influenced by the wind in the lower layer (925 hPa and 850 hPa), the equivalent potential temperature, the convergence field, the moisture convergence and the topography. In Case 2010 (30 December 2010), OSTIA had the best numerical simulation with diverse atmospheric conditions, and the maximum difference in the numerically simulated snowfall between NCEP/NCAR SST and OSTIA was 20 cm. Although there was a regional difference in the snowfall according to the difference in the SST, OSTIA and RTG SST numerical tests, it was not as significant as in the previous results. A higher SST led to the numerical simulation of larger snowfall, and the difference was greatest near Buan in the west coast area.

A Study on the Operating Control of a 2-Stage Heat Pump System with Screw Compressors (스크류 2단 압축 열펌프 시스템의 운전 제어 방안에 관한 연구)

  • Kim, Ji-Young;Baik, Young-Jin;Lee, Young-Soo;Ra, Ho-Sang
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.501-505
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    • 2006
  • A preliminary performance test of a 30RT 2-stage screw heat pump was carried out in order to develop a high performance large-scale unutilized energy source heat pump, which will be used in district heating and cooling. Two issues on the system control were investigated in this study, A stable 2-stage heating operation is guaranteed only if the load-side water inlet temperature is over a certain value, to where the 1-stage heating operation should be done first from a cold start. An oil shortage problem in low stage compressor, which depends on the degree of suction superheat, was solved by the proper oil level control scheme.

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A Conceptual Study 'Ming(明)' in Shanghanlun : Based on 2 Cases Treated by Shanghanlun Provisions (『상한론(傷寒論)』 '명(明)'에 대한 고찰 : 변병진단체계(辨病診斷體系)에 입각해 치료한 양명병(陽明病) 증례 2례에 근거하여)

  • Kim, Hyeong-Seop;Cho, Seong-Hwan;Lee, Sung-Jun
    • 대한상한금궤의학회지
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    • v.10 no.1
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    • pp.15-35
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    • 2018
  • Objectives : This study is to propose a new hypothesis about the interpretation of 'Ming (明)' in Shanghanlun and the direction of future research about Yangmingbing(陽明病). Methods : We analyzed the original form of the chinese characters 'Ming(明)' and tried to understand their contexts in Shanghanlun. At the same time, we analyzed 2 clinical cases diagnosed and treated as Yangmingbing according to newly hypothesized definition. Results : From etymology, 'Ming(明)' means becoming distinct. Patients in 2 cases suffered from cold hypersensitivity of hands and feet, overactive bladder syndrome and dizziness, all of which became distinct and problematic. For this reason, we diagnosed patients with Yangmingbing(陽明病) and administered herbal medicine then they improved. Conclusions : The disease names in Shanghanlun have clinical message by the name itself. From etymology, at least in 15 characters provision of Shanghanlun, Yanmingbing means the disease made by becoming conscious about symptoms. Future research about Yangmingbing (陽明病) should start from here.

A Study of Victor Pelevin' Short Story "Nika" (?레빈의 「니까」 다시 읽기 - 작가의 서사전략과 세계관을 중심으로 -)

  • Choi, Haeng Gyu;Ahn, Byong Yong
    • Cross-Cultural Studies
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    • v.33
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    • pp.287-307
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    • 2013
  • One cat caused a big wave in Russian literature. This cat revived the heroine of Russian classics. Her light breath was scattered in the world, in the cloudy sky and in the cold spring wind about one hundred years ago. And the cat gave an opportunity of turning to Russian classics to Russian readers. Thanks to this cat, a Russian dreamer changed his typical thinking, as well as many ordinary readers start to read works of creator of this wonderful cat. Pelevin accomplished these works with one cat, which he has made. Of course "Nika" is not only caused to make readers to return to Russian classics. I think, the cat and "Nika" are the symbols of writer's purpose in Russian literature. In this study the understanding of "Nika" is following the steps of realization of writer's purpose. In the second chapter it is analyzed to the textual relationship between "Nika" and "Light breath". Apart from existing analyses to be emphasized the succession of thematic aspect of two works as well. Existence of observers to each heroine stress this succession of thematic aspect of two works. In the third chapter it is analyzed the use of technique of mystification in "Nika". This intentional use of mystification has been demanded to read a "Nika" from another point of view(internal speculation of hero-narrator). The purpose of writer was to expose the cognitive error of a human being. I think this purpose was effectively explained by Pelevin's Buddhist world view which was introduced in his several works.