• 한국결정성장학회지
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• 제1권2호
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• pp.46-58
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• 1991

$Zn(NO_3)_2\cdot6H_2O$ 를 사용하여 출발용액으로 $Zn(NO_3)_2\cdot6H_2O$(aq.)용액을 각각 1M, 0.5M, 0.25M, 0.1M의 농도로 제조하여 초음파 진동자에 의해 액적을 발생시킨후, 2.3cm/sec의 유속으로 건조 및 열분해하여 ZnO분말을 합성하였다. 이때 건조 온도는 $200^{\circ}C$, 열분해 온도는 $600^{\circ}C$였다. 제조된 ZnO분말의 열적특성을 TG-DTA로 측정하였고, IR로 미분해물 및 흡착 가스의 성분을 조사하였다. 결정상 및 crystallite의 크기를 XRD로 분석하였고, 입자의 형태는 SEM과 TEM으로 관찰한 후 입자 크기와 입도분포를 SEM 사진으로부터 측정하였다. 합성 분말은 hexagonal의 결정구조를 갖는 Zinc oxide였다. 입자의 형태는 대부분 구형이고, 약 40nm 크기의 일차입자로 구성된 이차입자였다. 평규 입자 크기는 $0.28-0.61{\mu}m$ 이고 입도 분포도 좁았다.

• 한국정보통신학회논문지
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• 제4권2호
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• pp.505-516
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• 2000

셀룰러 신경망은 국부적 연결특성을 가지고 있어 실시간 영상처리에 폭넓게 이용되는 비선형 정보처리 시스템이다. 본 논문에서는 소규모의 $CNN(6\time6)$ 셀 블록을 이용하여, 크고 복잡한 처리에 적합한 시다중화 기법을 처리할 수 있는 CNN칩을 설계하였다. 대부분의 출력 형태는 기준 레벨화된 출력에 기인하여 흑백 영상처리에 적합하나, 본 논문의 출력형태는 아날로그 상태값으로 나타나기 때문에 그레이 레벨 영상처리에 적합하다. CNN 칩은 $0.65\mum$ 2P2M N-Well CMOS 공정으로 설계되었으며, 설계된 칩은 15400여개의 트랜지스터로 구성되며 칩면은 $1.85\times1.75m^2$ 이다. 설계된 $6\time6CNN$칩은 그 보다 큰 입력 영상에 대한 윤곽선 검출의 실험을 통하여 회로의 동작을 검증하였다.

• 화훼연구
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• 제19권4호
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• pp.206-211
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• 2011

절화 국화 '백마'의 수확 후 수송조건 및 생장조절제 처리가 선도유지 및 품질에 미치는 영향을 알아보기 위하여 절화 국화 '백마'를 공시재료로 사용하였다. 수송조건 실험 결과 저장온도에 따른 절화 품질은 $5^{\circ}C$ 저온 저장시 상온(대조구)저장과 $20^{\circ}C$ 저장 보다 효과적임을 확인하였다. 또한 수송방법에 따른 절화 품질은 물올림 처리 후 수직 수송방법이 다른 처리구에 비하여 우수한 효과를 나타내었다. 특히 생장조절제 uniconazole $10mg/L^{-1}$ 문무 처리는 개화를 지연시켜 선도를 유지시켰으며 daminozide 1,000배 분무 처리는 꽃목 굽음을 지연시켜 절화 국화 품질 유지에 우수한 결과를 나타내었다.

• 한국대기환경학회지
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• 제4권2호
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• pp.57-66
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• 1988

Sandy dust phenomena was observed from April 19 to 23, 1988 in Seoul and suspended particulate was collected by Andersen air sampler during this period. The samples were analyzed for 16 components $(SO_n^{2-}, NO_3^-, Cl^-, PO_4^{3-}, NH_4^+, F^-, Al, Fe, K, Cu, Mn, Na, Pb, Mg, Ca, Cd)$. The conclusions are as follwes: 1. Total suspended particulate concentation during the period of sandy dust phenomena was 489 $\mug/m^3$ (ordinary times: 140-125 $mug/m^3$) 2. The water - soluble ion component concentration of suspended particulate during the period of sandy dust phenomena was few and the metal concentration of that was more than that of ordinary times. 3. The cumulative frequency distribution of suspended particulates in logarithmic diagram did not show similar to normal log distribution during the period of sandy dust phenomena. 4. $SO_4^{2-}, NO_3^-, Cl^-, and PO_4^{3-}$ was onsided to coarse particle, and $NH_4^+$ and F to fine particle in the size distribution of water - soluble ion components during the period of sandy dust phenomena. 5. Metal concentration was high and Al, Fe, Cu, Mn, Na, Mg, and Ca was onsided to coarse particle, and K, Pb, and Cd to fine particle in the size distribution of metal components. 6. During the period of sandy dust phenomena the quantity of respirable particle (< 1 $\mum$) was about 3 times and that of metal components were about 2 - 11 times than that of ordinary times. 7. The concentrations of $NO_3^-, Cl^-, NH_4^+$ at ordinary times were 1.1 - 4 time than that of the period of sandy dust phenomena.

• 대한치과보철학회지
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• 제34권2호
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• pp.309-319
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• 1996

This study was performed to evaluate the fracture toughness of seven commercially available dental ceramics by indentation fracture method. All specimens were fabricated to the final dimensions of approximately 12mm in diameter 2mm in thickness. The characte-ristic indentation dimensions of Vickers or Knoop indentation were measured to calculate the fracture toughness values and Young’s moduli. The results obtained were summarized as follows; 1. Young’s modulus and Vickers hardness of Vita In-Ceram showed the maximum values of $154.4{\pm}49.2$ Gpa and $12.60{\pm}0.71$Gpa, respectively. Results of Scheff test exhibited the significant difference between Vita In-Ceram group and others(p<0.01). 2. Maximum fracture toughness of $2.562{\pm}0.37 MPam^{1/2}$ for Vita In-Ceram and the maxi-mum one of $0.908{\pm}0.132MPam^{1/2}$ for Vitadur-N were calculated. Results of Scheff test showed the significant difference between Vita In-Ceram group and Vita Hi-Ceram(p<0.05) : also between Vita In-Ceram or Vita Hi-Ceram and others(p<0.01). 3. The alumina-based core ceramics showed the aspect of Palmqvist crack for the indentation load of 49.0N, but others showed the median/lateral crack for the indentation load of 9.8N.

• 한국대기환경학회지
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• 제8권1호
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• pp.20-28
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• 1992

The x-ray fluorescence(XRF) is one of the most convenient and widely used techniques for analyzing trace elements in ambient particulate matters. The objects of the study were to estimate the optimum exposure time using the XRF, to investigate the distributions of heavy metal levels in particulate matters, and finally to study seasonal variation for the concentrations of total suspended particulate matters(TSP) and size fractionated particulate matters. The suspended particulate matters had been collected by a cascade impactor having 9 size fragnated stages for 3 years(Dec. 1988 to Nov. 1991) in Kyung Hee University-Suwon Campus. The particulate matters were then collected on each stage by membrane filters. The weight concentrations were determined by the XRF system. Thus, seasonal variations and relationship between concentration and particle size could be investigated. Resulting distribution was bimodal with the coarse and the fine particle groups minimum occurring around 2.1 to 3.3 $\mu$m as an aerodynamic diameter. To determine optimum exposure time of the XRF for various trace inorganic elements, membrane filters and the NIST standard filters were extensively studied. Using a statistical technique, optimum exposure time was estimated for each trace element and overall elements. The time was then determined as 20 seconds for the XRF system. The concentration of TSP was 123.9$\mum/m^3$ on an arithmatic average. The levels of each inorganic metal were Si 2420.0ng/$m^3$, Fe 977.1ng/$m^3$, and so on. The Pb. Zn, and Cu abounded in the fine mode group, while Ca, Fe, Si, Al, and K in the coarse group. Marked seasonal variation of TSP and metal concentrations was observed. The concentration of heavy metals in the fine mode was highest in winter : on the other hand, that in the coarse mode was highest in spring.

• 한국대기환경학회지
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• 제12권3호
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• pp.289-296
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• 1996

Effects of crustal species on the characteristics of ambient particles were studied by applying a gas-particle equilibrium model, SCAPE, to the measurements at Kosan, Cheju Island during the spring and summer, 1994. Two cases were simulated; the measured composition was used without any modification (case 1), and the metal ion concentrations originated from crust were subtracted from the measured particle composition (case 2). Total suspended particles (TSPs) were collected by an automatic high volume tape sampler during spring period and by high volume samplers during summer period. The fine particles, PM 2.5, and gaseous volatile species were collected using a filter pack smapler during summer period. The water soluble ion concentrations were analyzed from all the particle samples. According to the simulation results, the effect of crustal elements on the chemical composition of particles is negligible for both TSP particles and PM 2.5 particles. Acidity of particles measured at Kosan, however, is affected by the change of the concentrations of crustal species, stronger effects for TSP particles than for PM 2.5 particles during summer, and stronger effects during summer than spring for TSP particle. The average pH decrease due to the absence of crustal species was about 0.10 for PM 2.5 particle during summer and 1.51 and 0.85 for TSP particles during summer spring, respectively. Water contents of PM 2.5 particles for both cases are comparable to each other. Estimated water content of TSP particles for case 2 is higher than that for case 1 by about 4 $\sim 6 \mum/m^3$ because salts of metal ions are not hygroscopic.

• 한국응용곤충학회지
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• 제19권4호
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• pp.221-227
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• 1980

1979년 7월 경남 김해에서 딸기 성강 16호의 잎에 흑갈색 내지 암갈색 병반을 형성하는 병해를 발견, 그 병원균을 분리 검토한 결과 우리나라에서는 미기록병해인 Alternaria alternate (Fr.) Keissler로 동정되었으며 본병을 검은무늬병이라 명명하였다. 본균의 분생포자의 형태는 배지간에 차가 심하였으며 C.M.A.에서 평균 $20.1\times9.3{\mu}$, beak의 길이는 $4.0{\mu}$으로서 자연감염된 딸기잎상에서 형성된 것 보다 짧았다. 딸기 49품종에 접종한 결과 성강 16호와 Robinson이 고도감수성이였으며 Catskill, Cyclone, Northwest, Merton princes, Juspa, 및 대학 1호 등의 품종에도 발병을 볼 수 있었으나 31 품종은 전연 발병되지 않았다. 10종(14품종)에 접종한 결과 해바라기, 겹해바라기, 및 멕시코 해바라기에만 심하게 발병되었다.

• 한국대기환경학회지
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• 제12권4호
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• pp.441-448
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• 1996

The cyclone/annular denuder system/filter pack sampling system (ADS) was used to collect the acidic air pollutants in Chongju city. The data set was collected on nine different days with 24 hour sampling period from July 27 through August 27, 1995. The chemical species measured were $HNO_3, HNO_2, SO_2 and NH_3$ in the gas phase, and $PM_{2.5}(d_P<2.5 \mum), SO_4^{2-}, NO_3^- and NH_4^+$ in the particulate phase. Mean concentrations measured from this study were: $0.90 \mug/m^3 for HNO_3, 1.27 \mug/m^3 for HNO_2, 10.9 \mug/m^3 for SO_2, 4.82 \mug/m^3 for NH_3, 27.5 \mug/m^3 for PM_{2.5}, 5.24 \mug/m^3 for SO_4^{2-}, 1.22 \mug/m^3 for NO_3^-, and 1.64 \mug/m^3 for NH_4^+$. The fine particle $(PM_{2.5})$ mass measured for the ADS samples was slightly higher than the fine particle mass measured for the corresponding dichotomous sampler. For the wind coming from Chongju industrial complex the concentrations of acidic air pollutants measured were higher when compared with other directions. Specially, $SO_2 and PM_{2.5}$ concentrations for the wind coming from Chongju industrial complex were 3.6 and about 2 times, respectively, higher than those of other wind directions. High correlations were observed between $PM_{2.5} and fine particle's ion components $(r=0.82 with SO_4^{2-}, r=0.76 with NO_3^- and r=0.89 with NH_4^+). NH_4^+ and SO_4^{2-}$ was also highly correlated (r=0.97).

• 한국분말재료학회지
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• 제16권6호
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• pp.410-415
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• 2009

Hexagonal barium ferrite ($BaFe_{12}O_{19}$) nano-particles have been successfully synthesised using selfassembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. $BaFe_{12}O_{19}$ powders were synthesized with addition Fe ions to Ba-DEA complex and then heat treated at temperature range of 800-1000${\circ}C$. The molar ratio of Ba/DEA and heat-treatment temperature significantly affected the magnetic properties and morphology of $BaFe_{12}O_{19}$ powders. $BaFe_{12}O_{19}$ powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at 1000${\circ}C$ for 1 hour showed the coercive forces (iHc) of 4.84 kOe with average crystal size of about 200 nm.