• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.342-343
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• 2006

In order to develop the nano-sized WC powder that improved the hardness of hardmetals, carbothermal reduction of WO3 by C was examined by using the thermogravimetric analysis. At the direct carburization reaction path of $WO_3{\rightarrow}WO_{2.72}{\rightarrow}WO_2{\rightarrow}W{\rightarrow}W_2C{\rightarrow}WC$, the nano-sized grain was generated at the reaction stage $WO_{2.72}$ to $WO_2$ and W. For trial production, the intermediate products which consists of metal and carbide phases obtained by the first heating has been carburized to the final WC powder. We succeeded in the development of the WC powder of about 70nm. In addition, the nano-sized WC powder in which the vanadium of the most effective grain growth inhibitor was uniformly dispersed was developed.

• 한국작물학회지
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• 제44권3호
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• pp.230-235
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• 1999

To study the effects of an urease inhibitor, N-(n-butyl)-thiophosphoric triamide (NBPT), and a nitrification inhibitor, dicyandiamide (DCD), on nitrogen losses and nitrogen use efficiency, urea fertilizer with or without inhibitors and slowrelease fertilizer (synthetic thermoplastic resins coated urea) were applied to direct-seeded flooded rice fields in 1998. In the urea and the urea+DCD treatments, NH$_4$$^{+}$ -N concentrations reached 50 mg N L$^{-1}$ after application. Urea+NBPT and urea+ NBPT+DCD treatments maintained NH$_4$$^{+}$ -N concentrations below 10 mg N L$^{-1}$ in the floodwater, while the slow-release fertilizer application maintained the lowest concentration of NH$_4$$^{+}$ -N in floodwater. The ammonia losses of urea+NBPT and urea+NBPT+DCD treatments were lower than those of urea and urea+DCD treatments during the 30 days after fertilizer application. It was found that N loss due to ammonia volatilization was minimized in the treatments of NBPT with urea and the slow-release fertilizer. The volatile loss of urea+DCD treatment was not significantly different from that of urea surface application. It was found that NBPT delayed urea hydrolysis and then decreased losses due to ammonia volatilization. DCD, a nitrification inhibitor, had no significant effect on ammonia loss under flooded conditions. The slow-release fertilizer application reduced ammonia volatilization loss most effectively. As N0$_3$$^{[-10]}$ -N concentrations in the soil water indicated that leaching losses of N were negligible, DCD was not effective in inhibiting nitrification in the flooded soil. The amount of N in plants was especially low in the slow-release fertilizer treatment during the early growth stage for 15 days after fertilization. The amount of N in the rice plants, however, was higher in the slow-release fertilizer treatment than in other treatments at harvest. Grain yields in the treatments of slow-release fertilizer, urea+NBPT+ DCD and urea+NBPT were significantly higher than those in the treatments of urea and urea+DCD. NBPT treatment with urea and the slow-release fertilizer application were effective in both reducing nitrogen losses and increasing grain yield by improving N use efficiency in direct-seeded flooded rice field.field.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.207-207
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• 2017

The proso millet is vulnerable to lodging due to high plant height and shallow root. A lodging results in a hard mechanical harvesting and yield loss. One of solutions on this problem is inhibition of internode elongation. The objective of this study was to set up use time and dose of prohexadium-calcium, is growth inhibitor. The experimental variety was Ibaekchal. The experiment design was a split-plot design with three replications. The treatments were as follow: Main-plots were 25 and 35 day after sowing(DAS) as use time and sub-plots were 0%, 50%, 100%(diluted solution of 1000 times, $1000{\ell}\;ha^{-1}$), 150% as dose. The amount of nitrogen, phosphate and potassium fertilization were 90, 70, $80kg\;ha^{-1}$, respectively. The size of high ridge and plant spacing were $90{\times}30cm$ and $60{\times}15cm$, respectively. Proso millet was sown on June 9, 2016 by hands and was adjusted at 2 plant per hill. The growth survey of vegetative growth stage was conducted at 1 day before treatment and with one week interval after treatment. Data were collected: (1) grain yield: weight of grain in $kg\;ha^{-1}$, (2) 1000 grain weight: average weight of 1000 grain, (3) plant height: distance from soil to top of panicle or leaf in cm, (4) ear length: distance from top of stem to top of ear in cm, (5) stem diameter: diameter of second internode (6) degree of lodging: percentage of lodging area, etc. Analyses of variance were performed using R version 3.3.1(https://www. r- project. org). The Duncan's multiple range test(DMR) was used to separate treatment means at P < 0.05. There was a significant difference in plant height and number of stem among the use time and dose of prohexadium-calcium during vegetative growth stage. At 25 DAS, the difference with no treatment increased until 25 day after treatment and decreased since then. The difference in number of stem increased until 18 day and decreased since 25 day. At 35 DAS, the difference with no treatment in plant height and number of stem increased until 22 day after treatment and decreased since then. We assumed that the effect of prohexadium-calcium was inhibition of internode elongation and promotion of tillering, continued untel 25day after treatment. At 25 DAS, the degree of lodging deceased to 100%, 30%, 10% and 0% as dose increased. At 35 DAS, the degree of lodging decreased to 100%, 20%, 0% and 0% as dose increased. At 25 DAS, the yield was 2910, 2710, 3190, $2310kg\;ha^{-1}$ among dose. At 35 DAS, the yield was 2750, 2630, 2220, $2050kg\;ha^{-1}$. We recommend that the optimum use time and dose of prohexadium-calcium for proso millet is 1000 times diluted solution of $1000{\ell}$ per ha at 25 day after sowing.

• 한국분말재료학회지
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• 제5권4호
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• pp.279-285
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• 1998

The microstructures and mechanical properties of submicron WC-Co cemented carbides were investigated in relation to cobalt content. To inhibit the WC grain growth during sintering, VC was added as a inhibitor in each alloy with 3 mass% to the cobalt content. The WC-(5, 8, 10, 15, 20) mass% Co compacts were sintered at $1400^{\circ}C$ for 30 min in vacuum. Some of WC-(5, 8, 10) mass% Co sintered compacts were HIPed with 120 atm at 130$0^{\circ}C$ for 1 hr. The shrinkages of all HIPed alloys were increased without depending on the cobalt contents and the sintered densities of them. The relative densities of the alloys were increased with the cobalt content and HIPing. The less the cobalt content, the larger the WC grain. Many contiguities of WC grains were found in WC-5 mass% Co alloy. The sizes and numbers of pores in the alloys were decreased by HIPing. And also the strength and the hardness of each alloy were increased. The maximum hardness was about 18.95 GPa in the WC-5 mass% Co alloy HIPed and the maximum transverse-rupture strength (T.R.S.) 3.2 GPa in the WC-20 mass% Co alloy sintered.

• 한국잡초학회지
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• 제31권2호
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• pp.134-145
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• 2011

Myxococcus xanthus (MX, PX)와 Arabidopsis thaliana (AP37)의 protoporphyrinogen oxidase (Protox)유전자 과다발현 제초제 저항성 형질전환 벼와 비형질전환벼의 생육 및 수량에 관한 적응성 차이와 벼생육시기별 ALA 합성능력, tetrapyrrole 중간물질, 활성산소 발생, 지질과산화 작용 및 항산화효소 능력의 연관성이 조사되었다. Protox 과다발현 형질전환 벼 MX와 AP37의 초장은 이앙 후 43, 50, 65일에 비형질전환벼 비형질전환벼에 비해 유의적으로 적었고, 분얼수는 이앙 후 50일과 65일에 MX와 AP37 뿐만 아니라 PX에서도 비형질전환벼에 비해 유의적으로 적었다. 수확기의 간장과 수량은 MX, PX 및 AP37에서 그리고 고건중은 MX와 AP37에서 비형질전환벼에 비해 유의적으로 적었다. 형질전환벼 계통 MX, PX 및 AP37의 수량감소는 MX의 경우 영화수와 천립중에 의해, PX는 등숙율에 의해, AP37은 영화수, 등숙율 및 천립중에 의해서 기인되었다. 한편, 형질전환벼 계통 MX, PX 및 AP37의 수량감소는 또 다른 년차변이 연구에서도 관찰되었다. 이러한 형질전환벼계통의 생육 감소는 이앙 후 생육기간 뿐만 아니라 이앙 전 육묘기간 동안에서도 발생하여 결과적으로 수량이 감소되는 것으로 생각된다. Tetrapyrrole 중간물질 Proto IX, Mg-Proto IX 및 Mg-Proto IX monomethyl ester의 축적량, 활성산소종($H_2O_2$와 ${O_2}^-$), MDA, 및 항산화효소(superoxide dismutase, caltalase, peroxidase, ascorbate peroxidase, glutathione reductase) 및 엽록소 함량은 Protox 유전자 과다발현형질전환벼 계통과 비형질전환벼간에 유의적인 차이가 없어 이들 porphyrin 대사 경로 물질과 벼 생육 및 수량감소의 연관성은 적은 것으로 사료된다. 그러나 MX, PX, AP37의 ALA 합성능력은 광노출 후 1일과 이앙 후 52일에 비형질전환벼에 비해 유의적으로 감소하여 이 부분에 대한 상세한 연구가 추후에 수행되어야 할 것으로 보인다.

• 한국전기전자재료학회논문지
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• 제11권1호
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• pp.48-56
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• 1998

Pr\ulcornerO\ulcorner-based ZnO varistors were fabricated in the range of $Y_2$O$_3$additive content from 0.5 to 4.0mol%, and its microstructure and electrical properties were investigated. Yttrium was distributed nearly in the grain boundaries and the cluster phase formed at nodal point but more in cluster phase. The average grain size was decreased markedly from 34.9 to 8.6${\mu}{\textrm}{m}$ with increasing $Y_2$O$_3$additive content. It is believed that the decrease of grain size is attributed to the formation of cluster phase and the weakening of driving force for liquid sintering. As a result, $Y_2$O$_3$was acted as the inhibitor of the grain growth. With increasing $Y_2$O$_3$additive content, the varistor voltage, the activation energy, and the nonlinear exponent increased whereas the leakage current decreased, especially 4.0mol% $Y_2$O$_3$-added varistor exhibited very good I-V characteristics; nonlinear exponent 87.42 and leakage current 46.77nA. On the other hand, as $Y_2$O$_3$additive content increases, the varistor showed tendency of the salient decrease for donor concentration and the increase for barrier height. Conclusively, it is estimated that ZnO:Pr varistor compositions added more than 2.0mol% $Y_2$O$_3$are to be used to fabricate useful varistors.

• 한국세라믹학회지
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• 제51권5호
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• pp.442-446
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• 2014

Influences of Co and inhibitors from nano-sized WC materials were observed in the sintering process. VC and $Cr_3C_2$ were used as inhibitors. The crystal structure and surface images of sintered nano-sized WC materials, as functions of Co and inhibitors, were evaluated by XRD and FE-SEM analyses. The relative densities of sintered nano-sized WC materials did not change even with increased quantity of Co and increased temperature. The density of sintered nano-sized WC materials with inhibitors was lower than that of sintered nano-sized WC materials without inhibitors. No difference in hardness due to change of inhibitors was found.

• 전기화학회지
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• 제25권2호
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• pp.81-87
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• 2022

본 연구에서는, 알킬아민이 구리전해도금에 미치는 영향을 cyclic voltammetry를 이용해 분석해보았다. 수용액상 용해도를 갖는 알킬아민을 도금액에 첨가할 경우, Cu²⁺의 환원반응이 억제되는 것을 확인할 수 있었다. 다양한 알킬아민 중 1,12-diaminododecane에 대해 다양한 농도 및 도금액 조건에서 억제 효과를 관찰하였다. 1,12-diaminododecane은 산성 도금액상에서 protonation 되어, Cu²⁺의 착화제로써 작용하지 않았으며, 따라서 1,12-diaminododecane의 억제 효과는 Cu 표면상 흡착에 의한 것임을 확인할 수 있었다. 1,12-diaminododecane는 (i) protonation에 의한 양이온화와 그에 따른 Cu 표면상 기흡착한 음이온과의 정전기적 인력에 의한 흡착과 (ii) amine에 의한 Cu 표면상 직접 흡착의 두가지 특성을 모두 가지고 있었다. 흡착한 1,12-diaminododecane은 도금 반응을 억제할 뿐만 아니라, 구리도금막 형성시 3차원적 성장과 표면 미세화를 야기하였다.