SnO-P₂O₅계 유리에서 P₂O₅를 B₂O₃로 치환시 구조와 물성에 미치는 영향

김동환,황차원,김남진,임상혁,구동건,김태희,차재민,류봉기,Kim, Dong-Hwan,Hwang, Cha-Won,Kim, Nam-Jin,Im, Sang-Hyeok,Gwoo, Dong-Gun,Kim, Tae-Hee,Cha, Jae-Min,Ryu, Bong-Ki 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.1

The investigation is directed to lead free (Pb-free) frits that can be used for organic light emitting diode, plasma display screen devices and other sealing materials. $P_2O_5$-SnO system glasses have been prepared for Pb-free low temperature glass frit. Structure and properties of the glasses with the composition SnO-$xB_2O_3-(60-x)P_2O_5$ (x=0, 5, 10, 15, 20, 25, 30, 35, 40 mol%) were characterized by infrared spectra (IR), X-ray diffraction(XRD), Density, Molar volume, Thermo mechanical analysis(TMA) and weight loss after immersion test. Glass transition temperature($T_g$), dilatometric softening temperature($T_d$) and chemical durability increased, and coefficient of thermal expansion($\alpha$) decrease with the substitution of $B_2O_3$ for $P_2O_5$ in the range of 0~25 mol%.

팔라시스이리응애에 대한 농약의 독성

김동환,김상수,김광식,현재욱,Kim, Dong-Hwan,Kim, Sang-Soo,Kim, Kwang-Sik,Hyun, Jae-Wook 한국응용곤충학회 2006 한국응용곤충학회지 Vol.45 No.2

감귤 병해충 방제용으로 사용되고 있는 37종의 약제에 대한 팔라시스이리응애의 감수성을 조사한 결과, difenoconazole, imibenconazole, azoxystrobin, dithianon, fluazinam, procymidon, streptomycin, tribasic copper sulfate 등의 살균제 8종과 dichlovos, imidacloprid, thiamethoxam 등의 살충제 3종, 그리고 milbemectin, tetradifon, dicofol, spirodiclofen 등의 살비제 4종은 팔라시스이리응애 알의 부화율에 대한 영향이 적었으며, propineb, difenoconazole, imibenconazole, azoxystrobin, dithianon procymidon 등의 살균제 6종과 bifenazate, tetradifon, spirodiclofen 등의 살비제 3종은 성충에 대한 독성이 낮았다. 농약이 살포된 점박이응애 알을 먹이로 공급하여 성충에 대한 이차독성을 검정한 결과, 살균제 2종(fluazinam, streptomycin)과 살비제 3종(machine oil, cyhexatin, halfenprox)이 독성이 낮은 것으로 나타났다. The toxicities of 37 commercial pesticides for citrus pests were evaluated to H, fallacis. Eight fungicides (difenoconazole, imibenconazole, azoxystrobin, dithianon, fluazinam, procymidon, streptomycin, tribasic copper sulfate), three insecticides (dichlovos, imidacloprid, thiamethoxam) and four acaricides (milbemectin, tetradifon, dicofol, spirodiclofen) had lower effect to the hatchability of eggs N. fallacis. Six fungicides (propineb, difenoconazole, imibenconazole, azoxystrobin, dithianon, procymidon) and three acaricides (bifenazate, tetradifon, spirodiclofen) showed lower contact toxicity to adult N. fallacis. The secondary toxicity of 26 pesticides to N. fallacis adult were evaluated. Two fungicides (fluazinam, streptomycin) and 3 acaricides (machine oil, cyhexatin, halfenprox) showed low toxicity when the prey (eggs of spider mite) was treated with pesticides.

열적, 화학적 강화에 의해 잔류응력이 형성된 유약층을 가진 도자기의 기계적 물성

김동환,맹지헌,한윤수,김형태,최성철,김형준,Kim, Dong-Hwan,Maeng, Jee-Hun,Han, Yoon Soo,Kim, Hyung-Tae,Choi, Sung-Churl,Kim, Hyeong-Jun 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5

In this study, we measured the thermally and chemically induced residual stresses on glaze using the photoelastic method. Porcelain with thermally induced residual stress showed compressive stress of 49 MPa for thermal expansion mismatch and a locally fluctuated stress field over the glaze layer due to compensation of compressive stresses around pores. In the case of chemically strengthened porcelain, the compressive stress on the glaze was 151 MPa which was around 3 times higher than the stress on thermally strengthened glaze. The trend of fracture strength of thermally and chemically strengthened porcelains was coincident with that of the residual stress of porcelains.

Squeezing in a Josephson-junction-based Parametric Amplifier

김동환,김덕영,김재일,이수용,Kim, Dong-Hwan,Kim, Deok-Yeong,Kim, Jae-Il,Lee, Su-Yong 한국초전도저온학회 2022 초전도와 저온공학 Vol.24 No.1

수직원통형 빙축열조내 외향용융과정시 열전달특성에 관한 연구 -작동유체의 유동방향 및 축열조 형상비에 따른 열성능 비교-

김동환,김동춘,김일경,김영기,임장순,Kim, D.H.,Kim, D.C.,Kim, I.G.,Kim, Y.K.,Yim, C.S. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.2

During the day time in summer, peak of air conditing load, and electric power management system lies under overloaded condition. The reason is the enlarged peak load value of electric power caused by increased air-cooling load in summer. To prevent load concentration during day time and overloaded condition of power management system, some energy storage methods are suggested. One of these methods is ice storage system. Water has some good properties as P.C.M.(Phase Chang Material) : Its melting point is the range of required operation temperature. It has large specific latent heat and is chemically stable compared to other organic or inorganic substances. It is cheap and easy to treat. This study represents experimental results of heat transfer characteristics of P.C.M. under the outward melting process in a vertical cylinder. We experimented with twelve combinations of conditions, i.e., three different inlet temperatures($7^{\circ}C,\;4^{\circ}C\;and\;1^{\circ}C$), two working fluid directions(upward and downward), and two aspect ratios, H/R(4 and 2). At the inlet temperature of $7^{\circ}C$ and $4^{\circ}C$, there was temperature stagnation region where the temperature of P.C.M. remains constant at $4^{\circ}C$ regardless of aspect ratio and direction of working fluid. This temperature stagnation occurs as the water, at its maximum density, flows down to the lower region. The phase change interface formed bell-shaped curve as the melting process continued. With a new set of conditions(4H/R, inlet temperature $4^{\circ}C$ and $1^{\circ}C$, downward/upwerd inlet direction), the movement of phase change interface was faster when the working flued inlet direction was downward. With the same set of conditions, melting rate and total melting energy were larger when the working fluid inlet direction was downward. The results were reversed when the other sets of conditions were applied.

귤응애에 대한 팔라시스이리응애의 포식특성

김동환,김상수,김광식,현재욱,Kim, Dong-Hwan,Kim, Sang-Soo,Kim, Kwang-Sik,Hyun, Jae-Wook 한국응용곤충학회 2006 한국응용곤충학회지 Vol.45 No.2

감귤의 중요 해충인 귤응애의 생물적 방제를 위한 목적으로 귤응애에 대한 팔라시스이리응애의 포식특성을 조사하였다. 25$^{\circ}C$ 항온조건에서 귤응애의 알, 유충, 전약충, 후약충에 대한 팔라시스이리응애 암성충의 1일간 포식량은 각각 20.1, 26.1, 18.2, 7.4개체로 유충에 대한 포식량이 가장 많았다. 온도에 따른 포식량 조사결과, 온도가 높을수록 포식량이 증가하였으며, 이 때 팔라시스이리응애가 귤응애 알을 포식한 후의 출산능력(팔라시스이리응애 출산 알수/포식된 귤응애 알수), 즉 전환율은 10$^{\circ}C$를 제외하고는 0.09로 일정하였다. 잎 절편의 지름을 각각 20, 40, 60 mm로 하여 귤응애 알을 먹이로 공급했을 때 1일간 포식량은 각각 21.1, 17.3, 16.7개로 잎 면적이 증가할수록 포식량은 감소하였다. 또한 팔라시스이리응애는 귤응애 알, 유충, 약충을 먹이로 공급하였을 때 먹이밀도가 증가할수록 포식량은 점차 증가하였으나 그 증가율은 점차 감소하는 Holling의 기능반응 H형의 특성을 보였다. 이상의 시험결과 팔라시스이리응애는 귤응애의 생물적 방제 인자로서 가치가 있는 것으로 판단된다. Predation of Neoseiulus fallacis was observed for biological control of Panonychus citri that is one of the major insect pests on citrus. The daily predation of development stages of P. citri by an adult female of N. fallacis were 20.1 eggs, 26.1 larvae, 18.2 protonymphs, and 7.4 deutonymphs at 25$^{\circ}C$, The daily predation of P. citri eggs by N, fallacis was observed under different temperatures. The predation was increased as the temperature rise. At this time, ratio of eggs production of l! fallacis after predation of P. citri eggs (number of eggs N. fallacis/number of eggs P. citri consumed by N. fallacis) was 0.09. The daily predation of P. citri eggs by N, fallacis was 21.1, 17.3, and 16.7 on the different arenas (diameter: 20, 40, and 60 mm), respectively. The predation was decreased as the arena of the leaf increase. The functional response of M fallacis to P. citri showed Holling's Type II response: the consumption of prey by N. fallacis increased as the density of prey increase but increasing rate was gradually reduced. As the result, it seemed that N. fallacis can be use for biological control of P. citri.

효율적 균일 방전을 위한 레이저 전극 형상 비교

김동환,주홍,최상삼,Kim, Dong-Hwan,Chu, Hong,Choi, Sang-Sam 한국광학회 1992 한국광학회지 Vol.3 No.2

엑시머 레이저나 TEA $Co_2$ 레이저로응용되는 균일 방전을 위한 전극 형상 설계에 중됴한 k 값과 전극의 크기에 고려되는 최소 허용 전기장의 위치와의 관계를 Chnag 형상과 Ernst 형상에 대해 각각 계산, 비교하였다. 이 결과는 전극 형상 설계에 있어서 초기 k 값 설정에 도움표를 제공한다. 전극 표면에서 각각의 전기장 세기를 비교하여 Ernst 형상이 Chang형상보다 2배내지 3배 정도로 균일 전기장 분포가 넓게 설계될 수 있음을 보였다. Calculation and comparison of the design parameter between Chang and Ernst profile that can be used for the uniform discharge in excimer or TEA $Co_2$ laser are carried out. This result can be used to establish the initial $\kappa$-value in the design of electron. Also, calculation shows that Ernst profile is 2-3 times superior to Chang profile in uniformity of electric field with respect to the same k-value ($0.001\le\kappa\le0.25$).

특집_혹서대비 닭 관리 점검 - 여름철 효과적인 파리제거 방안 -천적의 이용과 유인포획기를 동시에-

김동환,Kim, Dong-Hwan 대한양계협회 2009 월간 양계 Vol.41 No.6

무기인산염 함유 이상성 인산칼슘이 외방성 수직골 형성에 미치는 영향

김동환,권영혁,박준봉,정종혁,허익,Kim, Dong-Hwan,Kwon, Young-Hyuk,Park, Joon-Bong,Chung, Jong-Hyuk,Herr, Yeek 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.2

Purpose: In this study, the effect of micro-macroporous biphasic calcium phosphate(MBCP) incorporated with inorganic polyphosphate for bone regeneration in the calvaria of rabbit was evaluated. Materials and Methods: The procedure of guided bone regeneration was performed with titanium reinforced expanded polytetrafluoroethylene(TR-ePTFE) membrane. Four animal groups were compared : 1) TR-ePTFE membrane for negative control group, 2) TR-ePTFE membrane filled with MBCP for positive control group, 3) TR-ePTFE membrane filled with MBCP soaked in 4% inorganic polyphosphate for experimental group I, and 4) TR-ePTFE membrane filled with MBCP soaked in 8% inorganic polyphosphate for experimental group II. Results: 1. Negative control group showed the highest new bone formation at 16 weeks. 2. Positive control group showed the smallest new bone formation compared to other groups. 3. 8% inorganic polyphosphate induced more volume of bone formation, otherwise experimental group II did not show significant difference compared to negative control group. Conclusion: These results suggest that inorganic polyphosphate has a promoting effect on bone regeneration, possibly by enhancing osteoconductivity of the carrier and by increasing osteoinductivity of the defected alveolar bone tissue.

사탕무씨스트선충의 기주범위 검정

김동환,조명래,양창열,김형환,강택준,윤정범,Kim, Dong Hwan,Cho, Myoung Rae,Yang, Chang Yeol,Kim, Hyeong Hwan,Kang, Taek Jun,Yoon, Jung Beom 한국응용곤충학회 2016 한국응용곤충학회지 Vol.55 No.4

사탕무씨스트선충(Heterodera schachtii)의 피해가 2011년에 배추 주산지인 강원도 지역에서 확인되었다. 이 선충은 암컷이 씨스트를 형성하는 특성을 가지므로 농약에 의한 효과적인 방제가 어렵다. 따라서 사탕무시스트선충에 대한 비기주 작물을 선정하여 감염지역의 배추를 대체할 작물을 추천하고자 총 17과(科) 276품종의 식물에 대한 사탕무씨스트선충의 저항성을 검정하였다. 사탕무씨스트선충 접종 후 씨스트 발생 정도에 따라 감수성(susceptible), 중감수성(moderately susceptible), 저항성/비기주(resistant/immune)로 구분하였다. 검정 결과 감수성 106품종, 중감수성 40품종, 저항성/비기주 130품종으로 구분되었다. 씨스트가 전혀 형성되지 않은 작물은 가지, 토마토, 상추, 들깨, 당근, 셀러리, 수박, 참외, 오이, 호박, 부추, 양파, 파, 도라지, 더덕, 잔대, 콩 등이었다. 가지과, 국화과, 명아주과, 화본과 작물은 작물 및 품종에 따라 약감수성 또는 저항성/비기주 식물이 혼재하였다. 본 시험에서 사탕무씨스트선충이 전혀 발생하지 않아 저항성/비기주식물로 밝혀진 130품종은 사탕무씨스트선충 감염지의 배추를 대체할 작목을 추천하는데 활용할 수 있을 것으로 생각된다. Sugar beet nematode (Heterodera schachtii Schmidt) was first detected in 2011, in Chinese cabbage grown in the highland areas of Korea. Chemical control of the nematode by nematicides is not feasible due to its cyst-forming characteristics; therefore, the cultivation of non-host crops is a preferable alternative to utilize nematode-infected fields. In this study, a total of 276 plant cultivars belonging to 18 different families were screened to evaluate their resistance to the nematode. Based on the number of cysts formed following nematode inoculation, the tested crops were classified into 3 levels: susceptible, moderately susceptible, and resistant/immune. Among the 276 cultivars tested, 106 cultivars were susceptible, 40 cultivars were moderately susceptible, and 130 cultivars were resistant/immune. Among the resistant/immune cultivars, cyst formation was not observed on eggplant, tomato, lettuce, perilla, carrot, celery, watermelon, oriental melon, cucumber, pumpkin, chives, onion, welsh onion, balloon flower roots, deodeok (Codonopsis lanceolata), Jandae (Adenophora triphylla), and bean. Therefore, these plants are regarded as immune to the cyst nematode. However, many crops belonging to Solanaceae, Asteraceae, Chenopodiaceae, and Poaceae families showed moderate susceptibility or immunity, depending on the crop or cultivar. This study provides a basis for alternative crop recommendations for sugar beet nematode cyst-infected farms in Chinese cabbage production areas.