HFC-134a와 대체냉매 HFC-152a에 CF_3I를 혼합한 자동차냉매 특성

권일욱,박찬수,홍경한,문기선,최운수,서의경,윤갑식,이종인,하옥남 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

These days, an attention of environment has been increasing all over the world. to prevent the green house effect and destruction of an ozone layer, an ozone destruction potential(ODP) be zero and a refrigerant for low global warming potential(GWP) is needed. HFC-134a, in which hydrogen is mixed instead of chlorine is a refrigerant used for automobile conditioners and its destruction potential is ecologically zero. However, it is not considered as a perfect substitutive refrigerant as its GWP is high. It is studied refrigerant mixtures in which HFC-134a, HFC-152a and CF_3I with low GWP and zero ODP are mixed by experimentally and concluded as follows; 1. with the variation of speed of compressor outside temperature and flow rate, the heat of evaporator and compressor and coefficient of performance was varied, and influenced the air conditioner. 2. The pressure of evaporator was decreased with increasing the speed of compressor and that of the refrigerant HFC-134a was higher 21% than that of azotrope refrigerant mixed with CF_3I. The overall capacity of condensor and evaporator was increased and HGC-134a was higher than azotrope refrigerant mixed with CF_3I 3. The capacity of evaporator with the refrigerant HFC-134a was higher 6% than azotrope refrigerant mixed with CF31 and the required power with zaotrope refrigerant mixed with CF_3I was higher 11% than that of HFC-134a. 4. The COP of the refrigerant FHC-134a was higher 31% in 1000RPM. when outside temperature was increased, COP was decreased. 5. Performance of HFC-134a is better than azotrope refrigerant mixed with CF_3I but prefered zaotrope refrigerant mixed with CF_3I considering the environment.

가솔린엔진의 실린더 溫度特性에 關한 硏究

윤영춘,권기린 濟州大學校工科大學産業技術硏究所 1996 尖端技術硏究所論文集 Vol.7 No.2

The purpose of this study is to prevent the stick. scuffing. scratch between piston and cylinder in advance, to obtain data for duration test in actual engine operation. Therefore, temperature gradient in peripheral and axial distribution of cylinder bore were measured in use of 800cc class gasoline engine. The results obtained are summarized as follows ; 1) The maximum reaction force by overlap is 101.97kg. The skirt length at that position is 10mm from skirt upper. 2) The rear side temperature of top dead center is 142℃ in peripheral distribution, it is about 20℃ higher than thrust, anti-thrust, front side temperature. 3) The rear side temperature of bottom dead center is 125℃ in axial distribution, whereas the rear side of midway position temperature is 120℃. 4) The temperature of cylinder wall is about 20∼30℃ higher than temperature of cooling water. 5) The temperature of cylinder wall at top dead center in use of SAE ?? lubricating oil is 16℃ higher than SAE 20 at 6000rpm.

유치열기 정상교합아동의 측모두부방사선 계측연구

김지연,권장혁,김경호,박기태 大韓小兒齒科學會 2005 大韓小兒齒科學會誌 Vol.32 No.4

본 연구의 목적은 유치열기 부정교합의 진단자료로 사용할 수 있는 정상 계측치를 알아보는 것이다. 4세에서 6세 사이 유치열기 정상교합아동 32명의 측모두부방사선 계측사진 및 안모사진을 이용하여 악골 및 연조직의 전후방적, 수직적 관계를 분석하였다. 수평적인 골격성 계측항목 중 SNA는 83°,SNB는 78.72°,ANB는 5.28°를 나타내어 하악골이 상악골에 비해 후방에 위치하고 있었으며 수직적인 골격성 계측항목 중 Gonial angle은 127°를 나타내어 성인에 비하여 High angle pattern을 보였다. 연조직 분석에서는 성인에 비해 convex한 soft tissue profile이 관찰되었다. 치성 계측항목 중 U1 to SN은 91.04°, IMPA는 86.57°를 나타내어 성인에 비해 reteroclination된 상하악 유중절치가 관찰되었다. 정상교합아동의 골격성분석에서 여자가 남자에 비하여 평균 나이가 많음에도 불구하고 linear measurement는 전제적으로 남자가 여자보다 큰 수치를 보였다. The present study was designed to formulate cephalometric norms of normal occlusion for usage in orthodontic diagnosis of malocclusion in Korean children. Thirty two children, aged 4 to 6. with normal occlusion were chosen for this study. Sagittal and vertical relations were analyzed using lateral cephapogram and clinical photos and the measurements were compared with those of adults. On skeletal sagittal analysis, the mean values of the SNA and SNB angles were 83°and 78.72°. It showed that the mandible was retrognathic and retropositioned in comparison to those angle pattern in children and reduction of gonial angle due to counterclockwise rotation of the mandible. On dental analysis. the mean values of the U1 to SN and IMPA were 91.04° and 86.57°, This showed retroclined upper and lower deciduous teeth in comparison to adults. For values. the linear values were generally greater in males than females.

대구지역 가로수잎의 중금속

이찬형,윤현숙,박연준,권종대,노기철,장성환 한국환경과학회 2002 한국환경과학회지 Vol.11 No.12

This study was conducted to determine the contents of heavy metals in leaves of roadside trees according to different growth stages in Daegu city. The orders of heavy metal contents in leaves of roadside tree and soil were Fe〉Mn〉Zn〉Pb〉Cu〉Cr〉Cd and Fe〉Mn〉Zn〉Cu〉Pb〉Cr〉Cd, respectively. The contents of heavy metals in leaves of roadside trees and soil showed an increasing tendency as the levels of traffic volume increased. The contents of heavy metals in leaves on October were higher than those on May.

Electrochemical Activity Studies of Glucose Oxidase (GOx)‐Based and Pyranose Oxidase (POx)‐Based Electrodes in Mesoporous Carbon: Toward Biosensor and Biofuel Cell Applications

Kwon, Ki Young,Kim, Jae Hyun,Youn, Jongkyu,Jeon, Chulmin,Lee, Jinwoo,Hyeon, Taeghwan,Park, Hyun Gyu,Chang, Ho Nam,Kwon, Yongchai,Ha, Su,Jung, Hee‐,Tae,Kim, Jungbae WILEY‐VCH Verlag 2014 Electroanalysis Vol.26 No.10

<P><B>Abstract</B></P><P>A simple study using a fixed amount of mesoporous carbon (MSU‐F‐C) was performed for the comparison of pyranose oxidase (POx) and glucose oxidase (GOx) in their electrochemical performance under biosensor and biofuel cell operating modes. Even though the ratio of POx to GOx in the glucose oxidation activity per unit weight of MSU‐F‐C was 0.35, the ratios of POx to GOx in sensitivity and power density were reversed to be 6.2 and 1.4, respectively. POx with broad substrate specificity and an option of large scale production using recombinant <I>E. coli</I> has a great potential for various electrochemical applications, including biofuel cells.</P>

Comparison of In Vivo Three-Dimensional Glenohumeral Positions and Scapular Kinematics between Young and Older Male Groups

Ki Youn Kwon,김두섭,Seung Hoon Baik,Jin Woo Lee 대한정형외과학회 2021 Clinics in Orthopedic Surgery Vol.13 No.3

Background: Many researchers have questioned whether shoulder kinematics such as the glenohumeral position and scapular kinematics would be different in different age groups. However, studies comparing shoulder kinematics between different age groups have been rare. The aim of this study was to analyze and compare the three-dimensional (3D) glenohumeral position, scapular kinematics, and scapulohumeral rhythm (SHR) during scapular plane arm abduction between a normal young male group and a normal older male group. Methods: Twenty normal men (10 young and 10 older) were enrolled in this controlled laboratory study. Fluoroscopic images were obtained using a single plane X-ray system. Bilateral computed tomography scans were taken to create a 3D model. A 3D-2D registration technique was used to determine the 3D position and orientation of the bones of the shoulder. Results: During scapular plane arm abduction, there were significant differences in scapular kinematics between the groups. The older male group showed more upward rotation, posterior tilt, and external rotation than the young male group. On the other hand, the glenohumeral position such as superior inferior translation, anterior posterior translation, and external rotation of the humeral head did not show significant difference between the groups. The mean value of SHR for the overall arm elevation range from start to maximum elevation angle for the older group and young group was 2.298 ± 0.964 and 2.622 ± 0.931, respectively, showing a significant difference between the two groups (p = 0.035). Conclusions: Scapular kinematics and SHR were significantly different between the older male group and the young male group. Our study could provide reference values of shoulder kinematics for older men aged 55–65 years.

중수골 골절에 대한 최소 침습적 고정 방법

권기연 ( Ki Youn Kwon ),오진록 ( Jin Rok Oh ),곽지웅 ( Ji Woong Kwak ) 대한골절학회 2022 대한골절학회지 Vol.35 No.1

목적: 이 연구의 목적은 최소 침습적인 고정 방법인 K-강선 고정술 또는 골수강내 무두나사 고정술을 시행한 중수골 골절 환자에 대해 영상학적, 임상적 결과를 비교분석하는 데 있다. 대상 및 방법: 중수골 중위 및 원위간부 또는 경부 단순 골절에 대해 K-강선 또는 무두나사를 이용해 내고정을 하여 치료하였던 18세에서 55세 사이의 환자들 중 최소 6개월 이상 추시가 가능했던 환자들 52예(남자 46예, 여자 6예)에 대해 영상학적 평가(각변형, 단축), 수부 기능 평가(TAM, 악력, 환자의 주관적 기능 평가), 일상 및 직장으로의 복귀 시간, 합병증의 발생 빈도 등의 요소에 대해 비교분석하였다. 결과: 영상학적 평가, 수부 기능 평가, 합병증의 발생빈도의 측면에서 K-강선 고정군과 골수강내 무두나사 고정군 간 통계적인 차이는 없었으나(p>0.05), 일상 및 직장으로의 복귀는 골수강내 고정군이 빨랐다(p<0.05). 결론: 6개월 이상의 추시에서 중수골 골절에 대한 최소 침습적 치료법인 경피적 K-강선 고정술 및 골수강내 무두나사 고정술은 임상적 결과의 측면에서 차이가 없으나, 일상 및 업무로의 조기 복귀라는 측면에서는 골수강내 무두나사 고정술의 선택을 고려해 볼 만하다. Purpose: This study compared the radiologic and clinical outcomes of metacarpal fractures treated with two minimally invasive surgical techniques: Kirschner wire (K-wire) fixation and headless screw fixation. Materials and Methods: This study included 52 patients (46 males and 6 females; age 18-55 years) with distal metacarpal fractures (middle and distal shaft, including the neck) who had undergone K-wire fixation or headless screw fixation. All subjects were followed up for at least six months. The radiologic assessments were performed to evaluate the angular deformity and shortenings. The total active motion (TAM), grip strength, and patients’ subjective functional assessment were measured to evaluate the hand function. The time taken to return to work (RTW) and adverse events were analyzed. Results: Of the 52 cases, metacarpal fractures treated with headless screw fixation and K-wire fixation showed a significant difference associated with early RTW (p< 0.05). There were no significant differences between the subjects treated with K-wire fixation and those with headless screw fixation in terms of the radiologic measurement, hand function examinations, complications, and adverse events (p >0.05). Conclusion: After a six-month follow-up, minimally invasive K-wire fixation and headless screw fixation produced similar clinical and radiologic outcomes in subjects with metacarpal fractures. Compared to K-wire fixation, however, headless screw fixation led to earlier functional recovery and might be a better option for treating metacarpal fractures in this regard.

선박 곡부재 계측 포인트에 대한 곡면 모델링 방법

권기연(Ki-Youn Kwon),김병철(Byung Chul Kim) (사)한국CDE학회 2020 한국CDE학회 논문집 Vol.25 No.3

Forward and afterward parts of ship and offshore structures are composed of curved plates with a thick thickness. It takes mush time to process the curved plate. If the fabricated curved plate has some dimensional errors, the additional cost is incurred in the assembling process. So, it is important to assess accurate dimensions for fabrication. Recently, photometric systems and 3D laser scanners have been used for this purpose. The dimensional assessment for fabrication is evaluated by comparing the surface created from the measurement points with the design surface. A B-spline surface interpolation is generally used to create the measurement surface, but there may be errors depending on the number and position of measurement points. In this study, we propose a method to improve the generation of the measurement surface. The mesh refinement method is used to obtain an accurate curved surface using a small number of measurement points. A Hermite curve interpolation is applied to reduce the error of the final generated surface. For accurate interpolation, the exact tangential direction is calculated at the vertex of an element, and errors are evaluated for various calculation methods.

플랜트 건조에서 경량모델 기반 용접선 생성 방법

권기연(Ki-Youn Kwon) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.05

선박 및 해양 구조물 곡부재 치수 품질 관리를 위한 가공완성도 평가

권기연(Ki-Youn Kwon),이재용(Jaeyong Lee) 한국해양공학회 2018 韓國海洋工學會誌 Vol.32 No.2

The forward and afterward parts of ships and offshore structures are designed to improve the fuel consumption performance. These are made of curved plates with a large thickness. If a fabricated curved plate has some dimensional errors, a lot of additional cost is incurred in the assembly process. Thus, an accurate dimensional assessment is very important for fabrication. In this paper, we propose an assessment method for the dimensional quality management of curved plates. This can be applied to data measured using a variety of three-dimensional instruments, with boundary measurement points automatically classified and sorted to create a measurement surface. The assessment is evaluated after matching the CAD surface and the measured surface considering constrained conditions. The fabrication assessment is evaluated as a probability of how much the tolerance is satisfied.