안팎 형상이 비대칭인 쌍동선의 자항성능 CFD 해석에 관한 연구

이종현,박동우 해양환경안전학회 2024 해양환경안전학회지 Vol.30 No.1

본 연구에서는 너클 라인이 다수 존재하면서 안팎 형상이 비대칭으로 설계된 특이점을 갖는 쌍동선의 자항성능을 예측하기 위해 CFD 해석을 수행하였고, 해석 기법에 따른 차이를 파악하기 위해 MRF(Moving Reference Frame) 기법과 SDM(Sliding Mesh) 기법을 적용하였다. MRF 기법을 적용한 경우에는 time step당 프로펠러를 1˚ 회전시켰고, SDM 기법의 경우 10˚, 5˚, 1˚씩 회전시키며 각 기법별 예측된 자항성능을 비교하였다. 자항점 추정을 위한 몇 가지 프로펠러 회전수에서의 해석 결과 중 프로펠러의 토크는 기법에 따른 차이가 거의 없었지만 추력 및 선체가 받는 저항은 MRF 기법보다는 SDM 기법을 적용했을 때 더 낮게, SDM 기법의 time step당 프로펠러 회전각이 작을수록 높게 계산되었다. 선형 내삽을 통해 추정된 자항점의 프로펠러 회전수, 추력, 토크와 실선 확장법을 사용해 추정된 실선의 전달동력, 반류 계수, 추력 감소 계수 및 프로펠러 회전수도 동일한 경향을 보였으며, 대부분의 자항효율은 반대의 경향을 보였다. 프로펠러 후류의 경우 MRF 기법을 적용했을 때 정확도가 떨어졌고, SDM 기법의 time step당 프로펠러 회전각에 따라 표현되는 후류의 차이는 거의 없었다. In this study, simulations based on computational fluid dynamics were performed for self-propulsion performance prediction of a catamaran that has asymmetrical inside and outside hull form and numerous knuckle lines. In the simulations, the Moving Reference Frame (MRF) or Sliding Mesh (SDM) techniques were used, and the rotation angle of the propeller per time step was different to identify the difference using the analysis technique and condition. The propeller rotation angle used in the MRF technique was 1˚ and those used in the SDM technique were 1˚, 5˚, or 10˚. The torque of the propeller was similar in both the techniques; however, the thrust and resistance of the hull were computed lower when the SDM technique was applied than when the MRF technique was applied, and higher as the rotation angle of the propeller per time step in the SDM technique was smaller in the simulations for several revolutions of the propeller to estimate the self-propulsion condition. The revolutions, thrust, and torque of the propeller in the self-propulsion condition obtained using linear interpolation and the delivered power, wake fraction, thrust deduction factor, and revolutions of the propeller obtained using the full-scale prediction method showed the same trend for both the techniques; however, most of the self-propulsion efficiency showed the opposite trend for these techniques. The accuracy of the propeller wake was low in the simulations when the MRF technique was applied, and slight difference existed in the expression of the wake according to the rotation angle of the propeller per time step when the SDM technique was applied.

키토산-폴리비닐 하이드로젤에서 사람 치은 모세포와 정상인 구강각화세포의 성장차이

이종현,박경주,이종헌 대한구강악안면병리학회 2007 대한구강악안면병리학회지 Vol.31 No.5

Many researchers are interested in wound healing in the t reatment of burns, prevention of post surgical adhesions and cosmetic s urgery by excess collagen production and scar formatlOn Synthetic epidermal substi tutes with cultured epi thelial cells seem to be an attractive strategy since keratinocytes have been demonstrated to modulate fibroblast growth and collagen synthesis. Bioa bsorbable and biocompatible chitosan structurally mimics hyaluronic acid. Recently, a bio compatible synthesi zecl ch itosa n-PVP(polyvinyl pyrrolidone) hydrogels demonstrated in vitro biocompat ibi li ty for bio medical applications . However. there is no re port on this hydrogeJ"s ability to modulate human gingival fibroblast growth. The purpose of this study were to investigate different growth modulation between human gingival fibroblast and normal human oral keratinocyte by chitosan- PVP hydrogel, and to apply this biocompatible synthetic polymer to oral and maxillofacial wound healing. We have synthesized a hydrogel from chitosan-PVP and examined its effect on human gingival fibroblast growth modulation in vitro. Non-toxic and biocompatible hydrogel with human gingival fi broblasts and epithelial cells was tested by MTT assay. HGF showed a higher growth proliferation than that of NHOK after cell seeding. In MTT assay, 30% hydrogel leach out products showed a higher cellular viability in NHOK than that of any other products. In MTT assay, 30% hyclrogel leach out products showed relatively lower cellular viability of HGF ln growth profile, NHOK showed about 7 fo lcls higher than HGF after 1 day, while about 2 fo lds higher after 5 days. And also NHOK showed above about 70% cell ular via bility from 1 to 7 days. It suggested that Chitosan-PVP hydrogel would inhibit relatively the growth of HGF and s timulate the growth of NHOK_ This phenomenon may prove to be of use in wound management 0 1' oral and maxillofacial area as epitheli al substitutes.

수소환원법에 의한 수용액 중 Cu-Al$_2$O$_3$ 복합분말제조

이종현 한국분말야금학회 1997 한국분말재료학회지 (KPMI) Vol.4 No.2

$Cu-Al_20_3 $ composite powders were prepared by hydrogen reduction of $Cu^{2+}$ from ammoniacal copper sulfate solution on alumina core using autoclave. The copper reduction rate and the properties of copper layer were investigated using Scanning Electron Microscope(SEM), X-ray diffractometer, size and chemical analyzers. The reduction rate of $Cu^{2+}$ showed the maximum value when the molar ratio of [$NH_3$]/[$Cu^{2+}$] was 2. In order to prevent the agglomeration of Cu powder and ethane reduction rate, $Fe^{2+}$ and anthraquinone which act as catalysis were added in the solution. Catalysis was effectively chanced with the addition of two elemerts at a time. Optimum conditions obtained in this study were hydrogen reduction temperature of 205$^{\cire}C$, stirring speed of 500 rpm and hydrogen partial pressure of 300 psi. Obtained $Cu-Al_20_3 $ composite Powders were found to have the uniform and continuous copper coating layer of nodule shape with 3~5 $\mu$m thickness.

FET형 반도체 바이오/이온 센서(Ⅰ)

이종현,이광만,김의락,이흥락,박이순,손병기,김기완 경북대학교 센서기술연구소 1990 연차보고서 Vol.1990 No.-

본 연구의 목적은 종래의 바이오/이온센서들의 문제점을 크게 극복할 수 있는 새로운 FET형 바이오/이온센서의 개발이다. 현재 여러 가지 생체관련물질이나 이온을 정량하기 위하여 분광광도계 (spectrophotometry)나 이온선택성 전극 (ion selective electrode)등의 장비가 사용되고 있으나, 용적이 크고 분석시간이 길기 때문에 미세한 국소부위의 측정이나 화학공정 또는 의료진단등의 현시적 모니터링에 적용하기가 불가능하다. 그러나 FET형 바이오/이온센서는 반도체 제조공정으로 제조되므로 극소형화 및 규격화가 용이할 뿐만 아니라 양산화가 가능하여 경제성이 크다. 따라서 FET형 바이오/이온센서의 개발은 국소부위 의료진단용, 각종 화학공정의 측정 및 제어, 환경공학적 감시관리 등의 기존의 센서를 적용하기 어려운 다양한 응용분야를 유발할 것이다.

감성 및 방재용 센서 및 시스템 개발

이종현 경북대학교 센서기술연구소 1996 연차보고서 Vol.1996 No.-

쌀의 품종에 따른 제1제한 아미노산 산정 및 흰쥐의 단백질 급원 배합 비율을 달리한 식이의 질적평가

이종현,김성애 충남대학교 자연과학연구소 1987 忠南科學硏究誌 Vol.14 No.2

This study was to determine the 1st limiting amino acid(LAA) in Korean menu by using different varieties of rice. Further investigation on quality of protein were done by studying the optimum combination with least square method. In order to see the possibility to use these combinations, economical aspects were also compared. The effects of different combinations of soybean, fish powder as protein sources were studied by feeling experimental rats for 3 weeks. Weight gains, FEB, PER and other biochemical measurements were compared to see whether 1/3 is the most desirable ratio of animal protein to total protein. The results were as following: 1. Methionine & cystine amounts of different varieties of rice influenced the most in determining the 1st LAA. 2. When rice combined with legumes, rice: mung bean(7:1) had A.S. of 92 and rice: kidney beans (4:1) had A.S. of 78. 3. Rice combination with pork-showed more even distribution of essential amino acid patterns. 4. Rice with ham were the most expensive where rice combined with chicken were the least expensive among rice with meats. 5. Growth rate, FEB, PER of the experimental rats feeding soybean + fish powder in ratio of 2:1(IV) gave the hight score. This considered with the recommended animal protein to total protein ratio of 1/3.

사행 채널 폭의 치수 변화에 따른 바나듐 레독스 플로우 배터리의 성능 변화에 관한 수치해석적 연구

이종현,김정명,박희성 대한기계학회 2019 大韓機械學會論文集B Vol.43 No.6

본 연구는 전기화학적 반응과 유체역학의 복합적 계산을 위하여 화학종을 포함한 종합적인 보존 법칙과 운동학적 모델을 사용하여 수치해석을 수행하였다. 삼차원 형상에 관한 셀 전압, 바나듐 이온 농도, 과전압, 압력강하, 펌프 소모 동력, 그리고 전력 기반 효율이 40mL/min에서 100mL/min까지 변하는 전해질 유량과 1.9mm에서 9.6mm까지 변하는 사행 채널 폭의 치수 변화에 대해 계산되었다. 사행 채널을 추가하는 것이 이온 농도 분포의 균일성과 전해질 확산 효과를 향상시켜 높은 셀 전압을 발생시키며 전해질 유량 60mL/min일 때 1.9mm의 사행 채널을 갖는 바나듐 레독스 플로우 배터리에서 최대 전력 기반 효율 96.63%이 계산되었다. 이에 본 연구는 특정 유속 범위 내에서 최적치수의 폭을 갖는 사행 채널을 추가하는 것이 전력 기반 효율의 향상을 위한 효과적인 방법이 될 수 있음을 제시하였다. In this study, a numerical simulation of a vanadium redox flow battery was investigated for reactions involving electrochemical species using comprehensive conservation laws and a kinetic model. For a 3-D geometry of the cell, the cell voltage, vanadium concentration, overpotential, pressure loss, pumping power, and power-based efficiency were calculated at flow rates ranging from 40 mL/min to 100 mL/min and serpentine flow field dimensions ranging from 1.9 mm to 9.6 mm. Extending the flow field was shown to improve the concentration distribution and diffusion effect, resulting in a higher cell voltage. A maximum power-based efficiency of 96.63 was calculated for a vanadium redox flow battery with a flow field of 1.9 mm at 60 mL/min. Consequently, this study suggests that the addition of an optimal-sized flow field within a specific flow rate can be an effective way of improving the powerbased efficiency.

고속가공을 이용한 자동부품 시작 금형 가공

이종현,이동주,신보성,최두선,이응숙,이득우,김석원 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-

Recently, to be satisfied the consumer's demand th life cycle and the lead time of product is to be shorted. So it is important to reduce the time and cost in manufacturing prototypal mold. These days, in order to reduce the lead time and cost high speed machining is highlighted. In the paper, using the high speed machining and aluminum-7075, the fundamental experiment is implemented in the change of cutting force, machining time, surface characteristic according to the tool path. And then the prototypal mold of the automatic knob is machined.

SOI 기술을 이용한 on-chip mass flow 센서의 개발

이종현 경북대학교 센서기술연구소 1991 연차보고서 Vol.1991 No.-

자궁절제술에 대한 임상적 관찰(Ⅱ)

이종현 충남대학교 의과대학 지역사회의학연구소 1978 충남의대잡지 Vol.5 No.1

A clinical analysis was made on the total 70 cases of hysterectomy which were done at the department of obstetrics and gynecology, Chungnam National University Hospital, from Jan. 1, 1976 to Dec. 31, 1976. The results were as follows: 1. The incidence of hysterectomy was 90.0% in the total abdominal hysterectomy and 10. 0% in the vaginal hysterectomy. 2. The age distribution was 22-65 years and the major group was in 36-50 years of age (62. 9%). The average age of the patients was 42. 2 years. 3. The average of the parity was 3. 6. The average of living children was 3. 3 per each patient. 4. The major pathological findings were chronic cervicitis, myoma, adenomyosis and endom-etrial hyperplasia in the order named. 5. The complications after surgery were occurred in 3 cases of the total 70 cases. 6. The average hospital stay after operation was 8. 2 days. 7. The incidence of combined operation of oophorectomy was bilateral oophorectomy in 30. 0% and unilateral oophorectomy in 35.7%.