L자형 이동상수로에서 댐 붕괴파의 수치해석

김대근,황건,Kim, Dae-Geun,Hwang, Gun 한국수자원학회 2012 한국수자원학회논문집 Vol.45 No.3

댐 붕괴 직후에 댐 붕괴 근역에서의 댐 붕괴파 및 댐 붕괴파로 인한 하상변동을 추적하기 위하여 RANS를 지배방정식으로 하는 FLOW-3D를 이용한 3차원 수치모의를 수행하였다. 특히 이동상에서의 하상변동과 그 하상변동으로 인한 홍수파의 변동을 고정상에서의 해석결과와 비교하였다. 그 해석 결과를 정리하면 다음과 같다. 첫째, L자형 실험수로에서의 홍수파 해석 및 이동상 실험수로에서의 홍수파와 하상변동 해석 결과는 해당 수리실험을 만족스럽게 재현하고 있다. 둘째, 부유사의 농도는 홍수파의 전면에서 가장 높은 값을 보이며, 하상침식은 흐름이 급변하는 댐 직하류 지점에서 가장 크게 발생한다. 수로의 상류에서 발생하는 부유사로 인해 하류에서는 침식과 퇴적이 번갈아서 발생한다. 홍수파가 도달하는 초기에는 L자형 만곡부의 내측에서 침식이 우세하게 발생하나, 시간이 지나며 침식은 점차 만곡부의 외측으로 이동하는 양상을 보인다. 셋째, L자형 이동상에서의 홍수파는 하상의 침식 및 퇴적으로 인해 고정상에서의 홍수파에 비해 그 전파가 지체되며 홍수위가 크게 상승한다. We conducted a three-dimensional numerical simulation by using the FLOW-3D, with RANS as the governing equation, in an effort to track the dam-break wave.immediately after a dam break.in areas surrounding where the dam break took place as well as the bed change caused by the dam-break wave. In particular, we computed the bed change in the movable bed and compared the variation in flood wave induced by the bed change with our analysis results in the fixed bed. The analysis results can be summarized as follows: First, the analysis results on the flood wave in the L-shaped channel and on the flood wave and bed change in the movable-bed channel successfully reproduce the findings of the hydraulic experiment. Second, the concentration of suspended sediment is the highest in the front of the flood wave, and the greatest bed change is observed in the direct downstream of the dam where the water flow changes tremendously. Generated in the upstream of the channel, suspended sediment results in erosion and sedimentation alternately in the downstream region. With the arrival of the flood wave, erosion initially prove predominant in the inner side of the L-shaped bend, but over time, it tends to move gradually toward the outer side of the bend. Third, the flood wave in the L-shaped channel with a movable bed propagates at a slower pace than that in the fixed bed due to the erosion and sedimentation of the bed, leading to a remarkable increase in flood water level.

버뮤다그래스 페어웨이에 퍼레니얼라이그래스 오버시딩에 따른 두 초종의 밀도 및 품질 변화와 Trifloxysulfuron-sodium 처리에 의한 전이시기 조정

김대근,전재만,오상익,심규열,Kim, Dae-Gun,Jen, Jae-Man,Oh, Sang-Ik,Shim, Gyu-Yul 한국잔디학회 2012 한국잔디학회지 Vol.26 No.2

When perennial ryegrass was overseeded in bermudagrass fairway, shoot density of perennial ryegrass was gradually increased to $88,000/m^2$ at the end of May, however dramatically decreased to 0 in September over the rainy season. On the other hand, that of bermudagrass increased from $2,000/m^2$ in March to $20,000/m^2$ in early June, and then decreased to $4,000/m^2$ at the end of July, after the rainy season, rapidly increased to $50,000/m^2$ in early September. Overseeding bermudagrass fairway with perennial ryegrass was maintained a good quality from mid-April to mid-June and decreased the quality over the rainy season from late June to July, and then turf quality was decrease to the worst level at the end of July. After the rainy season fairway quality was improved gradually and was the highest-level during September and early October. Trifloxysulfuron-sodium was treated to minimize the deterioration in turf quality due to early bermudgrass transition time in spring. Consequently, transition was started in mid-May and shoot density of bermudagrass treated by trifloxysulfuron-sodium was $70,000/m^2$ in mid-June. Even in the rainy season it was sustained as $30,000/m^2$, approximately three times higher than that of untreated overseeding fairway. 버뮤다그래스에 퍼레니얼라이그래스를 오버시딩 했을 때 퍼레니얼라이그래스의 밀도는 3월부터 점차적으로 증가하여 5월 말에는 88,000주/$m^2$를 유지하였다. 그러나 장마기를 거치면서 급격히 줄어들어 9월 초순경에는 0주/$m^2$가 되었다. 반면에 버뮤다그래스의 밀도는 3월경에 2,000주/$m^2$에서 온도가 증가함에 따라 점차 증가하여 5월 중순경에 10,000주/$m^2$, 6월 초순경에는 20,000주/$m^2$로 증가하였으며, 장마기를 거치면서 일조량 부족으로 7월 중순경에는 4,000주/$m^2$로 떨어졌다. 장마 후에는 밀도가 급격히 증가하여 9월 초순경에는 50,000주/$m^2$ 정도를 유지하였다. 퍼레니얼라이그래스로 오버시딩한 버뮤래스 페어웨이의 품질은 4월 중순부터 6월 중순까지 좋은 품질이 유지되다가 장마기이후 7월말에 가장 나빴으나 이후 점차 향상되어 9월 초순부터 10월 초순까지 좋은 품질을 나타내었다. 봄철 버뮤다그래스의 전이시기를 앞당겨 장마기의 품질저하를 최소화하기 위하여 trifloxysulfuron-sodium을 처리한 결과, 5월중순경부터 버뮤다그래스로 전이가 이루어져 6월 중순경에는 70,000주/$m^2$ 정도의 밀도를 보였으며 장마기에도 약 30,000주/$m^2$를 유지하여 무처리구에 비하여 약 3배 이상의 높은 밀도를 유지하였다.

고정상 및 이동상 수로에서 댐 붕괴파의 3차원 수치해석

김대근(Kim Dae Geun),황건(Hwang Gun) 대한토목학회 2011 대한토목학회논문집 B Vol.31 No.4B

본 연구에서는 RANS를 지배방정식으로 하는 3치원 수치모의를 이용하여 댐 붕괴로 인한 3차원적인 흐름 특징이 지배하는 댐 직하류에서 댐 붕괴파의 전파 현상, 특히 홍수파의 비정상성과 불연속성, 홍수파와 그 빈사파의 영향, 상류 및 사류 흐름의 혼재, 마른 하도에서의 전파, 이동상 수로에서의 전파와 같은 복잡한 현상을 포함하는 홍수파의 전파를 해석하였다. 부분 댐 붕괴로 인한 홍수파의 전파 해석과 90° 만곡을 가지는 실험수로에서의 홍수파 전파 해석에서는, 2차원 천수방정식을 지배방정식으로 사용하는 수치모의의 한계점으로 지적되었던 댐 붕괴 지점에서의 급격한 수위 변화와 저수지에서의 수위 진동 현상을 제대로 모의할 수 있었다. 또한 댐을 경계로 상류와 하류의 지형이 평행하거나 상류가 높은 또는 하류가 높은 계단형의 이동상 수로에서의 홍수파의 전파 및 하상변동을 성공적으로 모의할 수 있었다. This study analyzed the propagation of dam-break waves in an area directly downstream of a dam by using 3D numerical modeling with RANS as the governing equation. In this area, the flow of the waves has three dimensional characteristics due to the instantaneous dam break. In particular, the dam-break flows are characterized by a highly unsteady and discontinuous flow, a mixture of the sharp flood waves and their reflected waves, a mixture of subcritical and supercritical flow, and propagation in a dry and movable bed. 2D numerical modeling, in which the governing equation is the shallow water equation, was regarded as restricted in terms of dealing with the sharp fluctuation of the water level at the dam-breaking point and water level vibration at the reservoir. However, in this 30 analysis of flood wave propagation due to partial dam breaking and dam-break in channels with 90° bend, those phenomena were properly simulated. In addition, the flood wave and bed profiles in a movable bed with a flat/upward/downward bed step, which represents channel aggradation or degradation, was also successfully simulated.

CaO-Al₂O₃-SiO₂ 계 유리 스프레이 코팅막의 소성 거동에 대한 연구

나혜인,박제원,박재혁,김대근,최성철,김형준,Na, Hyein,Park, Jewon,Park, Jae-Hyuk,Kim, Dae-Gun,Choi, Sung-Churl,Kim, Hyeong-Jun 한국결정성장학회 2019 한국결정성장학회지 Vol.29 No.6

본 연구에서는 Al₂O₃ 소결체 표면에 두 종류의 CaO-Al₂O₃-SiO₂(CAS) 계 유리 분말을 스프레이 코팅(spray coating) 후 소성 거동에 대하여 연구하였다; (1) Si-rich, SiO₂ 함량이 높은 유리, (2) Ca-rich, CaO 함량이 높은 유리. Ca-rich 유리는 점도가 약 10⁷~10⁹ poise일 때 유리 내부에 잔존하는 기포들의 심한 발포 현상이 일어났고 이에 따라 소결 방해에 따른 수축율이 감소하였으며 조도는 증가하였다. 반면, Si-rich 유리의 경우, 1000℃ 이하에서는 Ca-rich와 같은 심각한 발포현상은 없었으나, 1200℃에서 밀도가 낮은 크리스토발라이트(cristobalite) 결정 발생과 함께 기포의 재발포 현상이 일어나 수축율이 감소하였으며 조도가 증가하는 이상 소성 거동을 보였다. 이는 저밀도 크리스토발라이트 결정 생성으로 인한 유리질의 칼슘 함량 증가에 의한 점도 감소로 생각된다. 따라서 CAS계 유리의 경우 저온 소성에서는 발포 현상에 의한 표면조도 상승과 소결 방해를 고려해야 하며, 특히 SiO₂ 함량이 높을 경우, 고온에서 결정화에 의한 이상 발포 현상도 생각해야 한다. Two types of CaO-Al₂O₃-SiO₂ (CAS) glass powder applied spray coating on the surface of sintered Al₂O₃ were researched for sintering behavior; (1) Si-rich, glass containing high content SiO₂, (2) Ca-rich, containing high content CaO. Foaming of bubbles remaining inside the Ca-rich glass was produced at a viscosity of approximately 10⁷~10⁹ poise, resulting in decreasing shrinkage (interfering with sintering) and increasing surface roughness. In case of Si-rich glass, there was no serious foaming bubbles phenomenon like Ca-rich below 1000℃, however cristobalite crystals with low density occurred at 1200℃ and then produced re-foaming of bubbles, resulting in abnormal sintering behavior. These phenomenon is considered to be a decrease in viscosity due to an increase in the Ca content of the glass according to the formation of low-density cristobalite crystals. Therefore, in case of CAS glass, it is necessary to consider the increase of surface roughness and the sintering interference because of foaming bubbles phenomenon at low temperature sintering. Especially, when containing high SiO₂ content, abnormal foaming phenomenon due to crystallization at high temperature should be predicted.

CaO-Al₂O₃-SiO₂ 계 벌크 유리와 스프레이 코팅막의 CF₄/O₂/Ar 플라즈마 식각 시 내식성 비교

나혜인,박제원,박재혁,김대근,최성철,김형준,Na, Hyein,Park, Jewon,Park, Jae-Hyuk,Kim, Dae-Gun,Choi, Sung-Churl,Kim, Hyeong-Jun 한국결정성장학회 2020 한국결정성장학회지 Vol.30 No.2

본 연구에서는 CaO-Al₂O₃-SiO₂(CAS) 계 유리 벌크와 유리 분체를 알루미나 소결체 표면에 스프레이 코팅막 적용 시 내플라즈마 특성에 대하여 비교하였다. CAS 유리 벌크와 유리 코팅막을 CF₄/O₂/Ar 플라즈마 가스에 노출시켰을 때의 식각율과 표면의 미세구조 분석을 통해 내플라즈마 특성을 확인하였다. CAS 유리 소성막은 유리 벌크와 비교하여 에칭속도가 최대 25배 빠른 것을 확인하였다. 유리 소성막의 표면 조도 값과 식각율 간의 통계학적으로 높은 상관성을 도출하였고, 이에 따라 소성막의 높은 표면조도가 빠른 식각을 유발하는 것으로 판단하였다. 그리고 유리 소성막은 Ca 성분의 함량이 적고, Si 함량이 많은 크리스토발라이트(cristobalite) 결정의 형성으로 인하여 Ca과 Ca 불화물에 의한 내플라즈마 효과가 감소한 것으로 판단된다. 따라서 CAS 유리 소성막은 유리 벌크에 비해 낮은 내플라즈마 특성을 갖는 것으로 판단된다. The difference of plasma resistance between the CAS glass bulk and coating films were compared. Plasma resistance was confirmed by analyzing the etch rate and the microstructure of the surface when the CAS glass bulk and the glass coating film were etched with CF₄/O₂/Ar plasma gas. CAS glass coating film was etched up to 25 times faster than the glass bulk. A statistically high correlation between the surface roughness and the etching rate of the coating film was derived, and thus, the high surface roughness of the coating film was determined to cause rapid etching. In addition, cristobalite crystals that has a low Ca content and a high Si content, was foamed on the glass coating film. Therefore, the CAS glass coating film is considered to have low plasma resistance compared to the glass bulk.

Monoterpenoid 계의 새로운 항암제 합성 및 In vitro 세포독성 평가

이민정(Min Jung Lee),백형근(Hyung Gun Baek),김대근(Dae Keun Kim),이강노(Kang Ro Lee),정규혁(Kyu Hyuk Chung),지옥표(Ok Pyo Zee),정영훈(Young Hoon Jung) 한국응용약물학회 2001 Biomolecules & Therapeutics(구 응용약물학회지) Vol.9 No.3

N/A Many attention has been focused on developing new chemotherapeutic agents for a treatment of cancer from natural products. From Carpesium divaricatum S. et Z. (Compositae), various monoterpenoid compounds were isolated and exhibited mild antitumor activity against human tumor cell lines. `These facts prompted us to explore the structure-activity relationship of these compounds. The synthesis of monoterpenoid compound was accomplished by Fries rearrangement, Grignard reaction, elimination, allylic oxidation, esterification and epoxidation as key steps. The results of in vitro cytotoxicity (A549, SK-OV-3, SK-MEL-2, XF498, HCT15) of the synthesised compounds are as follows: First of all, epoxide moiety is prerequisite for cytotoxic activity in diester compound. Any kind of compounds with olefin or diol moiety instead of epoxide ring exhibited poor or mild cytotoxic activity respectively. Of o-acetoxy and isobutoxy epoxy esters, p-substituted phenylacetate compounds exhibited high cytotoxic activities against SK-MEL-2 and HCT15.

세포질내 정자주입법(ICSI)에 있어서 정자흡입 및 난자내 주입방법에 관한 연구

이택후 ( Taek Hoo Lee ),김항진 ( Hang Jin Kim ),송건호 ( Gun Ho Song ),김대근 ( Dae Geun Kim ),전상식 ( Sang Sik Chun ),박윤규 ( Yoon Kyu Park ),서태광 ( Tae Kwang Suh ),전병균 ( Byeong Gyun Jeon ),류은경 ( Eun Kyung Ryu ),이은숙 대한산부인과학회 1997 Obstetrics & Gynecology Science Vol.40 No.12

Immobilization of spermatozoa prior to intracytoplasmic sperm injection(ICSI) sometimes results in crooked tail and this makes it difficult to aspirate sperm into an injection pipette tail first Head-first sperm aspiration into an injection pipette avoid this problem due to the bigger size of the sperm head. The effect of head or tail-first sperm injection into an oocyte on fertilization, cleavage, percentage of grade 1 embryos and development to blastocyst stage in ICSI program has been studied. A single living immobilized spermatozoa from oligoasthenozoospermic patient was injected into an oocyte head-first or tail-first according to the treatment. Eighteen hours after microinjection, oocytes were inspected for survival and fertilization Fertilized oocytes with two pronuclei were cultured in 30 μ I drop of mHTF supplemented with 10 % heat-inactivated follicular fluid(FF) at 37℃. On day 2, embryo transfer was performed with cleaved embryos. The remaining 2-8 cell stage embryos were co-cultured with BRL cells in mHTF+10 % FF for 72 hours and the developmental stage was observed. The data were analyzed by Analysis of Variance. A total of 164 oocytes from 36 cycles were assigned to each treatment and ICSI was performed(88 head-first, 76 tail-first). The rates of normal fertilization were 81.8 % and 76.3% for head-first and tail-first, respectively. Of the fertilized oocytes, the percentage of cleaved embryos and the percentage of grade 1 embryo among cleaved embryos were 88.9 % and 68.8 %, 93.1 % and 74.1 % for head-first and tail-first, respectively. Of the 2-8 cell embryos cultured, 44.4 %(16/36) and 50.0%(10/20) for head first and tail first, respectively developed to blastocyst stage. There were no differences in fertilization, cleavage, rates of grade 1 embryos, and development to blastocyst stage. In conclusion, head-first or tail-first sperm injection into an oocyte in ICSI program does not affect fertilization and subsequent embryo development to blastocyst stage in vitro.

한약재 물 추출물의 Monoamine Oxidase B의 활성 억제 및 항산화 활성 검색

이형철(Hyung Chul Lee),황상구(Sang-Gu Hwang),김대근(Dae Gun Kim),주성민(Sung Min Ju),유형근(Hyung-Keun You),김원신(Won Shin Kim),안원근(Won Gun An),전병훈(Byung Hun Jeon) 한의병리학회 2002 동의생리병리학회지 Vol.16 No.3

한약재 물 추출물의 아세틸콜린에스테라제 활성 억제 검색

이형철(Hyung Chul Lee),황상구(Sang-Gu Hwang),이영찬(Young Chan Lee),김대근(Dae Gun Kim),박영준(Young Jun Park),김태은(Tae Eun Kim),김명동(Moung Dong Kim),전병훈(Byung Hun Jeon) 한의병리학회 2002 동의생리병리학회지 Vol.16 No.2

세포질내 정자주입법(ICSI)에 있어서 정자흡입 및 난자내 주입방법에 관한 연구

이택후,김항진,송건호,김대근,전상식,박윤규,서태광,전병균,류은경,이은숙,문진수,김광철 경북대학교 의학연구소 2000 경북대학교병원의학연구소논문집 Vol.4 No.1

Study on Method of Sperm Aspiration and Injection into an Oocyte in Intracytoplasmic Sperm Injection(ICSI) Immobilization of spermatozoa prior to intracytoplasmic sperm iniection(ICSI) sometimes results in crooked tail and this makes it difficult to aspirate sperm into an injection pipette tail first. Head-first sperm aspiration into an injection pipette avoid this problem due to the bigger size of the sperm head. The effect of head or tail-first sperm injection into an oocyte on fertilization cleavage, percentage of grade I embryos and development to blastocyst stage in ICSI program has been studied. A single living immobilized spermatozoa from oligoasthenozoospermic patient was injected into an oocyte head-first or tail-first according to the treatment. Eighteen hours after microinjection, oocytes ware inspected for survival and fertilization Fertilized oocytes with two pronuclei were cultured in 30μl drop of mHTF supplemented with 10% heat-inactivated follicular fluid(FF) at 37℃. On day 2. embryo transfer was performed with cleaved embryos. The remaining 2-8 cell stage embryos were co-cultured with BRL cells in mHTF + 10% FF for 72 hours and the developmental stage was observed. The data were analyzed by Analysis of Variance. A total of 164 oocytes from 36 cycles were assigned to earth treatment and ICSI was performed(88 head-first, tail-first). The rates of normal fertilization were 81.8% and 76.3% for head-first and tail-first, respectively. Of the fertilized oocytes, the percentage of cleaved embryos and the percentage of grade 1 embryo among cleaved embryos were 88.9% and 68.8%, 93.1% and 74.1% for head-first and tail-first, respectively. Of the 2-8 cell embryos cultured, 44.4%(16/36) and 50.0%(10/20) for head first and tail first, respectively developed to blastocyst stage. There were no differences in fertilization, cleavage, rates of grade 1 embryos, and development to blastocyst stage. In conclusion, head-first or tail-first sperm injection into an oocyte in ICSI program does not affect fertilization and subsequent embryo development to blastocyst stage in vitro.