대향류 에틸렌 확산화염내 PAH 및 매연의 생성에 미치는 n-헵탄 혼합의 영향에 관한 연구

최재혁,한원희,Choi, Jae-Hyuk,Han, Won-Hui 해양환경안전학회 2012 해양환경안전학회지 Vol.18 No.1

매연과 다중고리 방향족 탄화수소의 생성에 대하여 n-헵탄의 혼합의 영향을 알아보기 위하여 순수에틸렌 대향류 확산화염에 n-헵탄을 소량 혼합하여 실험을 수행하였다. 매연체적분율과 PAH의 생성 계측에서는 레이저 유도 형광법 (laser-induced fluorescence; LIF)과 레이저 유도 백열법(laser-induced incandescence; LII)의 레이저 계측법을 이용하였다. 실험결과로 순수 에틸렌 화염에 소량의 n-헵탄을 혼합한 경우에는 매연과 다중고리 방향족 탄화수소가 상승하였다. 그러나 20% n-헵탄 혼합화염의 경우 LIF 신호가 감소하였다. 소량의 혼합화염의 경우, 다중고리 방향족 탄화수소와 매연의 상승은 n-헵탄 혼합에 의해 저온 영역에서의 메틸 라디칼의 증가로 의한다고 사료된다. 10% n-헵탄 혼합화염에 대한 화학반응 프로세스를 살펴본 결과 H 라디칼에 의한 반응율이 벤젠 생성에 결정적인 역할을 한다는 것을 알 수 있었다. In order to investigate the effect of n-heptane mixing on PAH and soot formation, small amount of n-heptane has been mixed in counterflow ethylene diffusion flame. Laser-induced incandescene and laser-induced fluorescene techniques were employed to measure soot volume fraction and polycyclic aromatic hydrocarbon(PAH) concentration, respectively. Results showed that the mixing of n-heptane in ethylene diffusion flame produces more PAHs and soot than those of pure ethylene flame. However, signals of LIF for 20% n-heptane mixture flame were lower than that of pure ethylene flame. It can be considered that the enhancement of PAH and soot formation by the n-heptane mixing of ethylene can be explained by methyl($CH_3$) radical in the low temperature region. And it can be found that reaction rate of H radical for 10% n-heptane plays a crucial role for benzene formation.

로봇용 자연급기형 연료전지의 최적구조에 관한 연구

최재혁,박상균,Choi, Jae-Hyuk,Park, Sang-Kyun 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.2

The performance of free-breathing polymer electrolyte membrane fuel cell (PEMFC) was studied experimentally and the effect of cathode separator structure on the cell performance was investigated. Cathode separators were used for the cell with $18cm^2$ active area. In channel type, the contact resistance is low, and the nature convection. which is strongly affected by the cross-sectional shape of cathode separator channel, is dominant in a cell performance. The maximum power density with $18cm^2$ active area is $105mW/cm^2$ using the 10mm depth and 2mm width channel. A computational analysis was optimum structure of free-breathing channel type PEMFC for robotic application.

인대 불안정성이 동반된 말기 족근 관절염 환자의 자가 인대 재건술과 인공관절 치환술의 치료 결과

최재혁,김정렬,김동현,정우철,윤정로,여의동,이경태,Choi, Jae-Hyuck,Kim, Jeong-Ryoul,Kim, Dong-Hyun,Chung, Woo-Chull,Yoon, Jung-Ro,Yeo, Eui-Dong,Lee, Kyung-Tai 대한족부족관절학회 2010 대한족부족관절학회지 Vol.14 No.1

Purpose: We report the clinical and radiographic result of ligament reconstruction using plantaris and total ankle replacement in end-stage ankle arthritis with ankle instability. Materials and Methods: The study is based on the 9 cases among total 48 patients of end-stage ankle arthritis that were treated with total ankle prosthesis and ligament reconstruction from 2007 to 2009 at least 12 months follow-up. We evaluated the VAS (Visual analogue scale) pain score, AOFAS (American orthopedic foot and ankle society) score and radiographic measurements. Results: Average age was 59.4 years (53~67 years) old. VAS pain score improved from preoperative average $8.2{\pm}0.9$ (range, 7~10) to $2.7{\pm}1.7$ (range, 0~6) and the AOFAS score improved from $46.4{\pm}14.6$ points (range, 23~69) to $80.1{\pm}9.3$ points (range, 65~95) at final follow-up. Anterior draw test improved $15.2{\pm}3.4$ mm (range, 12~23 mm) to $8.8{\pm}2.6$ mm (range, 6~13mm), varus stress test improved from $13.9{\pm}4.6^{\circ}$ (range, $10-18^{\circ}$) to $6.2{\pm}4.7^{\circ}$ (range, $2-18^{\circ}$) at final follow up. Conclusion: Plantaris ligament reconstruction is good option as part of the management of ankle instability with end-stage ankle arthritis. We achieved good clinical and radiographic results.

톨루엔 혼합에 따른 대향류 확산화염 내 매연 생성에 대한 수치적 연구

최재혁,윤석훈,윤두호,Choi, Jae-Hyuk,Yoon, Seok-Hun,Yoon, Doo-Ho 해양환경안전학회 2012 海洋環境安全學會誌 Vol.18 No.2

매연 생성에 대하여 톨루엔의 영향을 알아보기 위하여 순수에틸렌 대향류 확산화염에 톨루엔을 소량 혼합하여 수치해석을 수행하였다. 톨루엔($C_7H_8$)의 혼합 비율은 3%, 5%, 10%, 및 20%로 하였다. 계산에는 CHEMKIN III 기반의 Senkin 코드와 oppdif 코드를 이용하여 0-D 계산과 1-D 계산을 수행하였다. 0-D의 Senkin 계산에서는 톨루엔의 혼합율이 증가할수록 메틸라디칼의 농도는 증가하고 이에 따른 벤젠의 농도도 증가하였다. 이는 순수 에틸렌 화염에 톨루엔을 혼합할 경우 더 많은 매연이 생성될 것이라는 걸 의미한다. oppdif 코드에 의한 1-D 계산에서는 10% 톨루엔 반응식으로부터는 H 라디칼의 생성율이 결정적인 역할을 한다는 것을 알 수 있었다. 위 결과들로부터 확산화염 내 매연 생성에 있어 메틸라디칼, 벤젠과 H 라디칼이 중요한 역할을 한다는 것을 알 수 있었다. A numerical simulation has been performed to investigate effects of toluene mixing on soot formation in pure ethylene opposed-flow nonpremixed flame. Mixture ratios of toluene were 3%, 5%, 10%, and 20%. Senkin code for 0-D simulation and oppdif code for 1-D simulation based on CHEMKIN III were utilized. 0-D results by senkin showed that concentrations of methyl radicals and benzene were increased with increasing toluene mixture ratio. This implied that the mixing of toluene in pure ethylene diffusion flame produces more PAHs and soot than those of pure ethylene flame. 1-D result of 10 % toluene reaction by oppdif code showed that production rate for H radical was a crucial factor for benzene formation. These results imply that methyl radical, benzene and H radical play a important role on soot formation in diffusion flames.

미소중력 환경내의 벽면 근방 확산 화염 특성에 관한 수치 해석

최재혁,후지타 오사무,Choi Jae-Hyuk,Fujita Osamu 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.1

Characteristics of a laminar diffusion flame placed near wall in microgravity have been numerically analyzed in a two-dimension. The fuel for the flame is $C_2H_4$. The flame is initiated by imposing a high temperature ignition source. The flow field, temperature field, and flame shape in microgravity diffusion flame are detailed. Especially, effects of surrounding air velocity and fuel injection velocity on the microgravity diffusion flame have been discussed accounting for standoff distance. And, the effect of curvature rate has been also studied. The results showed that velocities in a diffusion flame were overshoot because of volumetric expansion and distribution of temperature showed regularity by free-buoyancy This means that the diffusion flame in microgravity is very stable, while the flame in normal gravity is not regular and unstable due to buoyancy. Standoff distance decreases with increase in surrounding air velocity and with decrease in fuel injection velocity. With increasing curvature rate, the position of reaction rate moves away the wall.

뉴욕주 커뮤니티 재활성화 지원체계 및 커뮤니티 참여에 관한 연구

최재혁,김용우,이준성,Choi, Jae-Hyuck,Kim, Yong-Woo,Lee, June-Seong 한국건설관리학회 2009 건설관리 : 한국건설관리학회 학회지 Vol.4 No.2

뉴욕 주의 커뮤니티 재활성화는 커뮤니티 중심의 계획을 기반으로 이루어지고 있으며, 이는 미국 내의 커뮤니티 계획에 있어서 일반적인 접근방법이다. 연방정부는 재정지원에만 주력하고 가능한 간섭을 하지 않고 있으며, 주정부가 재활성화에 필요한 계획, 재정, 인력, 정보 등을 지원하는 체계적인 지원체계의 수립에 더욱 노력을 기울이고 있다. 주정부는 다른 주정부, 지방정부, 대학들과 연계하여 커뮤니티의 재활성화에 필요한 인적 물적 자원들을 주의 실정에 맞게 재구성하고, 자체 지원시스템을 만들어, 커뮤니티가 스스로 재활성화 계획을 실행 할 수 있도록 돕고 있다. 본 연구에서는 뉴욕 주에서의 커뮤니티 재활성화 계획 과정이 어떻게 이루어지고 있으며, 계획과정 상 커뮤니티 구성원들의 참여가 어떻게 이루어지고 있는지, 본 연구자가 직접 참여한 The Black River Vision Plan/ City of Watertown의 사례연구를 통해 자세히 알아보았다. Community revitalization programs in New York State are community centralized projects, and this approach is pretty much general in the united states. However, local communities do not have enough funds, human resources, technical knowledge and useful data. Even though State governments have their own supporting systems, they are not able to support all that communities need and ask. State governments are, on the other hand, trying to develop the most efficient supporting system for the community revitalization programs as a part of community development. US federal government supports funds as well. New York state government makes connections with other states, local governments, universities, and other useful groups, and reorganizes all possible resources for New York state communities. This supporting system helps that local leaders and community residents can tackle regionally specific issues and opportunities. This paper shows how New York state implements community revitalization programs with the community supporting system. This research also shows how to organize and manage the community involvements in the planning process through the case study of the Black River Vision Plan/ City of Watertown that an author had participated in.

유산균 생산 후 폐기되는 부산물 첨가 사료의 급이가 잉어(Cyprinus carpio)의 성장률, 선천성 면역, 면역연관 유전자 발현 및 항균효과에 미치는 영향

최재혁,정상목,양은총,장태원,이찬흔,박관하,최상훈,Choi, Jae Hyeok,Jung, Sang Mok,Yang, Eun Chong,Jang, Tae Won,Lee, Chan Heun,Park, Kwan Ha,Choi, Sanghoon 한국어병학회 2022 한국어병학회지 Vol.35 No.1

This study has been performed to investigate the potential effects of by-product discarded after probiotics production (BPPP) on growth performance, immune gene expression, innate-immunity status, and disease resistance of carp, Cyprinus carpio. For 3 weeks, carp were fed four diets containing different levels of BPPP at 0, 0.1, 0.2 and 0.5% per kg of normal diet. Every 7 days of feeding, immune-related gene expression, serum lysozyme activity and ACH₅₀ were analyzed. Growth rates and challenge test with E. tarda were conducted after 3 weeks of BPPP feeding. Both lysozyme activity and ACH₅₀ were significantly (p<0.05) increased in all BPPP supplemented groups compared to the control at every 7 day for 3 weeks of feeding trial. The gene expression of pro-inflammatory cytokines, IL-1β and TNF-α was significantly (p<0.05) up-regulated until 21 days of feeding in all groups except for 0.2% group on day 7 post feeding. The anti-inflammatory cytokine IL-10 gene expression was only significantly (p<0.05) increased in 0.1% group on day 7 and decreased (p<0.05) on day 14 in all BPPP supplemented groups. On day 21, the IL-10 gene expression was augmented (p<0.05) in all groups. SOD gene expression was significantly (p<0.05) increased compared to the control on day 14 and 21 post feeding, whereas no significant difference was observed on day 7. In challenging test, 0.2%, 0.1%, 0.5% and control group showed 80%, 70%, 60% and 40% of survival rate, respectively. Feed conversion rate was only improved in 0.5% group. In conclusion, the present study indicates that dietary BPPP suplementation improved growth performance, innate immune response and bactericidal activity in carp.

외과 점액낭염의 내시경적 방법과 개방적 점액낭 절제술의 비교 연구

최재혁,김정렬,김동현,정우철,윤정로,오성록,이경태,Choi, Jae-Hyuck,Kim, Jeong-Ryoul,Kim, Dong-Hyun,Chung, Woo-Chull,Yoon, Jung-Ro,Oh, Seong-Rok,Lee, Kyung-Tai 대한족부족관절학회 2011 대한족부족관절학회지 Vol.15 No.2

Purpose: To compare the result of endoscopic versus open bursectomy in lateral malleolar bursitis, which was not treated conservatively. Materials and Methods: Between January 2008 and October 2009, We divided to two groups, endoscopy (group A) 11 cases, open bursectomy (group B) 11 cases. The average follow up period was 15 months (range, 12 to 18), the mean age was 66 (range, 38 to 79). We compared patients satisfaction, complete healing time, operation time, complications and recurrence. Results: Group A had significant difference in terms of the clinical satisfactions, complete healing time. operation time, complications. Group A showed satisfaction (excellent 9, good 2), mean complete healing time 11.9 (8~14) days, operation time 37 (25~45) minutes, 1 case recur. Group B showed satisfaction (excellent 4, good 3, fair 1, poor 3), complete healing time 32.7 (14~98) days, operation time 22 (18~26) minutes. complication were one case of skin necrosis, one case of wound dehiscence, two cases of superficial peroneal nerve injury, no recurrence. Significant advantages of endoscopic method include lower morbidity and rapid wound healing period (p<0.05). Conclusion: Endoscopic resection of the lateral malleolar bursitis is a promising technique and shows favourable results compared to the open resection. Significant advantages of this method include lower morbidiy and rapid wound healing.

LonWorks를 이용한 분산 지능 제어를 위한 통신 모듈의 설계 및 구현

최재혁,이태오,Choi Jae-Huyk,Lee Tae-Oh 한국정보통신학회 2004 한국정보통신학회논문지 Vol.8 No.8

본 논문은 애쉴론(Echelon)사의 LonWorks 기술을 이용하여 분산 지능 제어를 위한 LonWorks 통신 모듈 설계 및 구현에 대하여 논한다. LonWorks 통신 모듈은 하드웨어와 펌웨어(firmware)로 나눌 수 있다. 첫 번째, 하드웨어는 센서가 부착된 마이크로컨트롤러 부분과 제어와 데이터 네트워크를 함께 운용할 수 있는 LonWorks 구성요소이다. 즉, 뉴런 칩(neuron chip), 마이크로컨트롤러, 트랜시버(transceiver), LONCard로 구성되어 있다. 두 번째, 운용 펌웨어는 노드빌더(NodeBuilder) 3.0 개발 툴을 이용한 뉴런 C이다. 제작 구현된 LonWorks 통신 모듈은 LTM-10A, Gizmo 4 I/O board, 병렬 I/O 인터페이스를 이용하여 사전 테스트하였다. 그리고 필드 테스트를 위하여 마이크로컨트롤러 부분은 하이퍼터미널(HyperTerminal)을 이용하여 테스트하였고, 데이터 네트워크의 통신 절차는 윈도우즈용 LonMaker 툴을 이용하여 짧은 메시지를 송$.$수신하여 확인하였다. 이로써 LON(Local Operating Network)은 지능 디바이스를 가진 분산형 제어 기술을 사용하여 대형 제어시스템을 소형화할 수 있다. In this paper, we describes the design and implementation of LonWorks communication module for distributed intelligent control using LonWorks technology of Echelon. LonWorks communication module can be divided hardware and firmware. First, hardwares is divided into microcontroller attaching sensors and LonWorks components for working together control network and data network. Hardwares are consisted of neuron chip, microcontroller, transceiver, LONCard. Second, operating firmware is realized with neuron C using NodeBulider 3.0 development tool. Produced and implemented LonWorks communication module is pretested using LTM-10A, Gizmo 4 I/O board, parallel I/O Interface. For field test, microcontroller module part is tested by HyperTerminal, communication procedure in data network is certified by transmitting and receiving short message using LonMaker for Windows tool. Herewith, LON technology is based on network communication technique using LonWorks.

온톨로지 기반의 웹 페이지 분류 시스템

최재혁,서혜성,노상욱,최경희,정기현,Choi Jaehyuk,Seo Haesung,Noh Sanguk,Choi Kyunghee,Jung Gihyun 한국정보처리학회 2004 정보처리학회논문지B Vol.11 No.6

본 논문은 온톨로지(ontology)에 기반 한 자동화된 웹 페이지 분류 시스템을 제안한다. 웹 페이지의 분류를 위하여 첫 번째 단계에서는 각 웹 페이지가 속한 범주(category)를 대표할 수 있는 단어를 선정하며, 이를 위하여 단어빈도와 문서빈도를 곱한 값을 계산한다. 두 번째 단계에서는 첫 번째 단계에 의해 선택된 단어의 정보이득(information gain)을 계산해 분류 확률이 높은 단어를 우선적으로 선정한다. 두 단계를 통하여 선정된 단어들과 웹 페이지의 분류 정보를 가지고, 기계학습에 의하여 컴파일 된 규칙(compiled rules)을 생성한다. 생성된 규칙은 임의의 웹 페이지들을 도메인 온톨로지에 의해 정의된 범주 별로 분류할 수 있도록 한다. 본 논문의 실험에서는 주어진 웹 페이지 집합에서 각 범주 별로 평균 240개의 단어로부터 78개의 단어를 결과적으로 선정하였으며, 이를 바탕으로 웹 페이지 분류 규칙을 생성하였다. 실험 결과에서 제안한 시스템의 평균 분류 정확도는 약 83.52%로 측정되었다. In this paper, we present an automated Web page classification system based upon ontology. As a first step, to identify the representative terms given a set of classes, we compute the product of term frequency and document frequency. Secondly, the information gain of each term prioritizes it based on the possibility of classification. We compile a pair of the terms selected and a web page classification into rules using machine learning algorithms. The compiled rules classify any Web page into categories defined on a domain ontology. In the experiments, 78 terms out of 240 terms were identified as representative features given a set of Web pages. The resulting accuracy of the classification was, on the average, 83.52%.