• Title/Summary/Keyword: Choi Chang Hak

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Further Study on the Constituents of Allium tuberosum leaves

  • Choi, Jae-Sue;Go, Chang-Hak
    • Archives of Pharmacal Research
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    • v.19 no.1
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    • pp.60-61
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    • 1996
  • In the course of continuous work on the leaves of Allium tuberosum (Liliaceae), compounds 1 and 2 were isolated from the ethylacetate and butanol-soluble fraction, and identified as N-p-coumaroyl tyramine and bis(p-hydroxyphenyl) ether, respectively, on the basis of spectral data and physicochemical results.

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Artery to Collecting System Communication after Abdominal Trauma (복부 외상 후 발생한 동맥-집뇨계 간 연결)

  • Lee, Chang Ug;Kwon, O Jung;Bang, Sung Hak;Choi, Nak Young;Lee, Chang Sub;Ahn, Seung Hyun
    • Journal of Trauma and Injury
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    • v.19 no.2
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    • pp.192-195
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    • 2006
  • Degenerative vascular disease, previous arterial surgery, long-term ureteral stenting, pelvis surgery, and radiotheraphy are reported as causes of artery-to-collecting-system communication.. Artery-to-collecting-system- communication associated with blunt trauma is rare, but potentially fatal. The diagnosis is very difficult and requires a high degree of suspicion. We were able to make the diagnosis based on the characteristic finding of contrast-enhanced computed tomography (CT) obtained in the early phase, equivalent to the finding obtained in the corticomedullary phase of the kidney. We report a case of artery to collecting system communication due to blunt abdominal trauma following a fall, which was treated by embolization.

Effects of Casting Variables and Alloying Elements on the Fluidity of Thin Wall Stainless Steel Castings (박육 스테인리스 주강의 유동성에 미치는 주조변수 및 합금원소의 영향)

  • Choi, Hak-Kyu;Kang, Sang-Kyu;Park, Heung-Il;Jeong, Hae-Yong;Bae, Cha-Hurn
    • Journal of Korea Foundry Society
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    • v.20 no.5
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    • pp.336-343
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    • 2000
  • The effects of casting variables and alloying elements on the fluidity of thin wall cast stainless steels were investigated. Melts were poured into the sand molds to produce thin wall test castings. The length of it was 245 mm and the thickness varied at the interval of 0.5 in the range of 1.6 to 2.6 mm. For the same casting condition, the fluidities of austenitic stainless steel, ferritic, precipitation hardenable and martensite ones were better in the order. The higher the pouring temperature, the shorter the pouring rate and the better the fluidity were. The fluidity was increased with the addition of Cr and decreased with W and Nb.

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A Precision Micro-Positioning System by Using Hinge Mechanism

  • Choi, Hyeun-Seok;Lee, Hak-Joon;Han, Chang-Soo;Kim, Seung-Soo;Kim, Eung-Zu;Choi, Tae-Hoon;Na, Kyoung-Hwan
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1344-1348
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    • 2003
  • A precision micro-positioning system with a high displacement resolution and wide motion range has been required for industrialized applications in variety fields. This paper discusses the design of a precision micro-rotation stage with flexure hinges. Proposed system is applied to grinding machine for micro parts. Rotational motion is generated with this system. For this systems having a full rotation motion with high precision, a dual servo system with a coarse stage and a fine stage is proposed.

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Vibration Diagnosis of High Pressure LNG Pump (고압 LNG 펌프의 진동 진단)

  • Choi, Byeong-Geun;Kim, Hak-Eun;Choi, Chang-Lim;Lee, Jae-Myeong;Bang, Sang-Su
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.776-779
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    • 2005
  • Liquefied Natural Gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high Pressure LNG pumps determined the send out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current analysis have been performed. And high beat vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

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A Study on data cache locking policy for Packet Filtering System's performance improvement (패킷 여과 시스템의 성능 향상을 위한 데이터 캐쉬 잠금 방안 연구)

  • Cho, Hak-Bong;Choi, Chang-Seok;Moon, Jong-Wook;Jung, Gi-Hyun;Choi, Kyung-Hee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2003.11a
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    • pp.435-438
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    • 2003
  • 오늘날 네트워크 보호를 위해 firewall 과 같은 패킷 여과 시스템이 많이 보급되어 있다. 이러한 시스템에서는 해당 패킷의 생사 및 진행방향을 정할 수 있는 Rule 이 다수 존재하며, 각 패킷에 해당하는 Rule 을 검색하는 시간은 전체 네트워크의 응답시간을 지연시킨다. 더불어 해당 네트워크의 병목현상을 일으키는 주범이 될 수 있다. 본 논문에서는 데이터 캐쉬 잠금 방법을 활용한 네트워크 프로세서를 모델로, 캐쉬 잠금을 이용해 패킷 여과 Rule 의 접근 시간을 줄일 수 있는 파라미터를 찾고 수식화하며 Simulation 을 통해 효용성을 검토해 본다.

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Event based session timeout management policy (사건 기반 세션 Timeout 관리 정책)

  • Choi, Chang-Seok;Cho, Hak-Bong;Moon, Jong-Wook;Jung, Gi-Hyun;Choi, Kyung-Hee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2003.11a
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    • pp.439-442
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    • 2003
  • 세션 관리 시스템에서 많은 세션에 대한 timeout 처리 시 발생하는 오버헤드를 줄이기 위한 방법으로 기존의 time based timeout 관리 방식이 아닌, 세션 관리 시스템의 성격에 적합한, event based timeout 관리 방법을 제시하고 실험을 통해 확인해 본다.

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Synthesis and in Vitro Antibacterial Activity of Cephalosporins with a Pyridiniume Substituent Carrying an Isoxazole Moiety at the C-3 Position

  • Park, Hae-Il;Choi, Hyun-Joo;Jang, Jin-Hee;Choi, Sung-Hak;Rhee, Jae-Keol;Chang, Min-Sun
    • Archives of Pharmacal Research
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    • v.24 no.2
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    • pp.89-94
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    • 2001
  • Several quaternary pyridinium cephalosporin analogues were prepared analogues were Prepared and evaluated in vitro for antibacterial activity against selected Gram-positive and Cram-negative organisms. Most of the synthesized analogues were either as effective or less effective against the tested bacterial organ isms than the reference com pounds, Cefpirome and Ceftazidime.

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Home Network System Based on Wireless Sensor Network for Intelligent Service Robot (지능형 서비스 로봇을 위한 무선 센서 네트워크 기반의 홈 네트워크 시스템)

  • Choi, Hak-Soo;Lee, Kwang-Hee;Kim, Tae-Hyun;Lee, Chang-Kyun;Ahn, Ho-Seok;Lee, Min-Woo;Choi, Won-Il;Kyung, Kyu-Chul;Shin, Joong-Kil;Kim, Min-Hyuck
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.461-463
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    • 2007
  • 현재 아파트를 중심으로 가정에 보급되기 시작한 홈 네트워크 시스템은 단순 홈 서버를 기반으로 가정 내 다양한 기기들을 연결하고 외부 인터넷 망과 연동하는 등 여러 가지 시도가 있으나 아직까지 단편적인 서비스를 제공하는 수준에서 크게 벗어나지 못하고 있다. 본 논문은 이러한 현 홈 네트워크 시장 상황에서 다양하고 실질적인 응용을 실제로 구현하고 사용자와 상호작용하기 위해 인공지능을 갖춘 서비스 로봇을 활용함으로써 홈 네트워크 시장을 활성화하기 위한 방안을 제시한다.

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