• 한국토양비료학회지
• /
• 제9권3호
• /
• pp.211-220
• /
• 1976

서기(西紀) 2000년(年)까지의 비료(肥料) 소요량(所要量)을 농경학적(農耕學的) 측면(側面)에서 예측(豫測) 하기 위하여 작물(作物) 영양생리(營養生理) 면(面)에서의 예측치(豫測値), 토양비옥도(土壤肥沃度) 면(面)에서 본 예측치(豫測値), 그리고 경지(耕地)의 내외연적(內外延的) 확대(擴大)에 따르는 비료(肥料) 소요량(所要量)의 변동(變動) 예측치(豫測値)들을 종합(綜合) 검토(檢討)한 결과(結果)를 다음과 같이 요약(要約)한다. 1. 농업경제연구소(農業經濟硏究所)의 식량경제(食糧經濟) 문제(問題)의 종합적(綜合的) 분석(分析)에서 제시(提示)한 2000년(年)까지의 식량(食糧) 생산량(生産量) 예측치(豫測値)에 준(準)한 작물(作物) 생산(生産)을 위(爲)해 필요(必要)한 작물(作物)의 질소(窒素), 인산(燐酸) 및 가리(加里) 흡수량(吸收量)을 근거(根據)로 예측(豫測)한 값은 1980년(年) 1.162천(千)톤(N ;554.1천(千)톤, $P_2O_5$; 360.1천(千)톤, $K_2O$;247.8천(千)톤) 1900년(年) 1,471.4천(千)톤 (N; 694.8천(千)톤, $P_2O_5$;465.4천(千)톤, $K_2O$;311.2천(千)톤), 2000년(年) 1,764천(千)톤(N;812.5천(千)톤 $P_2O_5$; 592.3천(千)톤, $K_2O$;359.2천(千)톤)이였다.${\cdots}{\cdots}$ (제(第) I 안(案)) 2) 최근(最近)의 단위면적당(單位面積當) 수량(收量) 변동(變動) 추세(趨勢)로부터 2000년(年)까지의 작물별(作物別) 단위면적당(單位面積當) 수량(收量)을 예측(豫測) 하고 이들 수량(收量)을 올리는데 필요(必要)한 비료(肥料)의 증가율(增加率)을 작물(作物) 수량(收量) 증가율(增加率)과 같게 취하면서 경지(耕地) 면적(面積)의 내외연적(內外延的) 확대(擴大)를 고려(考慮)한 2000년(年)까지의 비료(肥料) 소요량(所要量) 예측치(豫測値)는 1980년(年) 1,149.3천(千)톤(N; 603.7천(千)톤, $P_2O_5$; 305.5천(千)톤, $K_2O$; 240.1천(千)톤) 1990년(年) 1,551.1천(千)톤(N; 814.7천(千)톤 $P_2O_5$; 412.3천(千)톤, $K_2O$; 324.0천(千)톤), 2000년(年) 2,253.8천(千)톤 (N;1,183.8천(千)톤, $P_2O_5$; 586.4천(千)톤, $K_2O$;470.9천(千)톤)이였다(II안(案)) 3) 최근(最近)의 작물별(作物別) 단위(單位) 면적당(面的當) 수량(收量)과 단위(單位) 면적당(面的當) 시비량(施肥量)의 변동(變動) 추세(趨勢)를 동시(同時)에 고려(考慮)한 2000년까지의 비료(肥料) 소요량(所要量) 예측치(豫測値)는 1980년(年), 1,287.6천(千)톤 (N; 677.1천(千)톤, $P_2O_5$: 342.0천(千)톤 $K_2O$; 268.5천(千)톤) 1990년(年) 2,085.6천(千)톤(N; 1,096.7천(千)톤 $P_2O_5$; 553.9천(千)톤, $K_2O$;435.0천(千)톤), 2000년(年) 3,380.6천(千)톤(N; 1,777.8천(千)톤) $P_2O_5$;897.8천(千)톤 $K_2O$; 705.0천(千)톤) 이었다. (III 안(案)) 4) 제(第)I안(案)은 장차(將次) 쌀에 대(對)해서만 자급율(自給率) 100%를 도모(圖謀)하고, 여타(餘他) 작물(作物)에 대(對)하여는 대략(大略) 50%의 자급율(自給率)을 기대(期待) 할 때 실제(實際)와 가까운 가능성(可能性)이 있으나 이 같은 상황(狀況)은 바람직한 것은 아닌 것 같다. 5) 식량(食糧)의 자급율(自給率)을 최대한(最大限) 높이기 위(爲)하여 경지(耕地)의 내외연적(內外延的) 확대(擴大), 다수성(多收性) 품종(品種)의 광범(廣範)한 보급(普及)이 따를 경우, 비료(肥料) 효율 증대(增大)를 위한 여러가지 기술(技術)들이 개발보급(開發普及)되면 제(第)II안(案)이 실현성(實現性)이 높고, 그 같은 기술(技術)의 보급(普及)이 미진(未盡)할 때는 제(第)III안(案)이 현실(現實)에 가까울 가능성(可能性)이 높다.

• Restorative Dentistry and Endodontics
• /
• 제48권1호
• /
• pp.3.1-3.14
• /
• 2023

Objectives: This study evaluated the effect of different nanoparticulated zinc oxide (nano-ZnO) and conventional-ZnO ratios on the physicochemical properties of calcium aluminate cement (CAC). Materials and Methods: The conventional-ZnO and nano-ZnO were added to the cement powder in the following proportions: G1 (20% conventional-ZnO), G2 (15% conventional-ZnO + 5% nano-ZnO), G3 (12% conventional-ZnO + 3% nano-ZnO) and G4 (10% conventional-ZnO + 5% nano-ZnO). The radiopacity (R_ad), setting time (S_et), dimensional change (D_c), solubility (S_ol), compressive strength (C_st), and pH were evaluated. The nano-ZnO and CAC containing conventional-ZnO were also assessed using scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Radiopacity data were analyzed by the 1-way analysis of variance (ANOVA) and Bonferroni tests (p < 0.05). The data of the other properties were analyzed by the ANOVA, Tukey, and Fisher tests (p < 0.05). Results: The nano-ZnO and CAC containing conventional-ZnO powders presented particles with few impurities and nanometric and micrometric sizes, respectively. G1 had the highest Rad mean value (p < 0.05). When compared to G1, groups containing nano-ZnO had a significant reduction in the S_et (p < 0.05) and lower values of D_c at 24 hours (p < 0.05). The C_st was higher for G4, with a significant difference for the other groups (p < 0.05). The S_ol did not present significant differences among groups (p > 0.05). Conclusions: The addition of nano-ZnO to CAC improved its dimensional change, setting time, and compressive strength, which may be promising for the clinical performance of this cement.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
• /
• pp.117-120
• /
• 2004

As the maximum power operating point (MPOP) of photovoltaic (PV) power generation systems changes with varying atmospheric conditions such as solar radiation and temperature, an important consideration in the design of efficient PV system is to track the MPOP correctly. Although the efficiency of these Maximum Power Point Tracking algorithms is usually high, it drops noticeably in case of rapidly changing atmospheric conditions. This paper describes common MPPT control algorithm: Constant Voltage Control, Perturbation and Observation(P&O), Incremental Conductance (IncCnd) and proposes a new MPPT algorithm based on P&O algorithm. The conception and control principles of the proposed MPPT method are explained in detail and its validity of the proposed method is verified through several simulated results. As it doesn't use digital signal processor, this MPPT method has the merits of both a cost efficiency and a simple control circuit design. Therefore, it is considered that the proposed MPPT method is proper to low power, low cost PV applications.

• 한국정밀공학회지
• /
• 제25권4호
• /
• pp.108-117
• /
• 2008

A transmission designed with P.T.O(Power Take-Off) axle for agricultural work vehicles including multi-purpose vehicles has been developed. It is focused on the 4-wheel drive transmission of synchronous contact type for practical use in fruit tree households which is required for a large-sized agricultural vehicle. Concerning to the specification performed, the load capacity is from 500kg to 1,000kg and the safety should be secured for passengers. In addition, the driving condition should also be secured under bad situations of the topographic slope, swampy land and the rest. In order to carry out above tests, a prototype vehicle through strength analysis of transmission design has been manufactured. Consequently, optimal design conditions on the power transmission with multi-purpose vehicle for various jobs are proposed such as an indication of optimal RPM and torque at a certain work situation. The performance test through the prototype of multi-purpose work vehicle is performed and the related data base is achieved. Finally, it is improved on troubles by the analysis of the results of R&D and provided the solutions on problems occurring to mass production in the future.

• 한국세라믹학회지
• /
• 제49권2호
• /
• pp.191-196
• /
• 2012

In this study, tin phosphate glass system($SnO_2-(1-x)P_2O_5-xB_2O_3$) that occur during the melting of the metal oxide inhibition of the oxidation reaction, and to reduce oxides of high melting temperature in the following three methods were melting. The first is the general way in the atmosphere, and the second by injecting $N_2$ gas under a neutral atmosphere, and finally in the air were melted by the addition of a reducing agent Melt in the atmosphere when the oxidation of the metal oxide is inhibited by low temperatures were melting. In addition, the deposition of crystals within glassy or inhibit devitrification phenomenon is also improved over 80% transmittance. This phenomenon, when the melting of glass, many of $Sn^{4+}$ ions are reduced to the $Sn^{2+}$ was forming oxides SnO, because it acts as a modifier oxide.

• 전자공학회논문지A
• /
• 제30A권7호
• /
• pp.60-74
• /
• 1993

Experiments of RIE of tungsten films using SF$_{6}$ plasma were conducted to investigate the effect of process parameters on etch rate, uniformity, anisotropy, and selectivity. As power increased, the etch rate increased. Maximum etch rate was obtained at 200mtorr As interelectrode spacing increased the etch rate increased for P < 200mtorr while it decreased for P> 200mtorr. Etch rate was maximum at 20 sccm gas flow rate. As substrate temperature increased, the etch rate increased and activation energy was 0.046 eV. In addition, maximum etch rate was acquired at 20% $O_{2}$ addition. The etch rate slightly increased when Ar was added up to 20% while it continuously decreased when N$_{2}$ was added. Uniformity got improved as pressure decreased and was less than 4% for P <100mtorr. Mass spectrometer was utilized to analyze gas composition and S and F peaks were observed from XPS analysis with increasing power. The anisotropy was better for smaller power and spacing, and lower pressure and temperature. It improved when CH$_{4}$ was added and anisotropic etch profile was obtained when about 10% $O_{2}$ was added. The selectjvity was better for smaller power larger pressure and spacing, and lower temperature. Especially. low temperature processing was proposed as a novel method to improve the anisotropy and selectivity.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권3호
• /
• pp.156-156
• /
• 2000

The piezoelectric properties and the doping effect for $0.95Pb(Zr_xTi_{l-x})O_3+0.O5Pb(Mn_{1/3}Nb_{2/3})O_3$compositions were studied. Also, the heat generation and the change of electromechanical characteristics, the important problem in practical usage, were investigated under high electric field driving. As a experiment results under low electric field, the value of $k_p$ and ${\varepsilon}_{33}^T$ were maximized, but $Q_m$ was minimized $(k_p=0.57, Q_m=1550)$ in the composition of x=0.51. In order to increase the values of $Q_m$, $Nb_2O_5$ was used as a dopant. As the result of that, the grain size was suppressed and the uniformity of grain was improved. Also, the values of $k_p$ decreased, and the values of $Q_m$ increased with doping concentration of $Nb_2O_5$ . As a experiment results under high electric field driving, when vibration velocity was ower than 0.6[m/s], the temperature increase was 20[℃], and the change ratio of mechanical quality factor was less than 10[%]. So, its electromechanical characteristics was very stable. Conclusively, piezoelectric ceramic composition investigated at this paper is suitable for application to high power piezoelectric devices.

• 센서학회지
• /
• 제13권2호
• /
• pp.152-156
• /
• 2004

The dielectric and piezoelectric properties of 0.36Pb($Sc_{1/2}Nb_{1/2}$)$O_{3}$-0.25Pb($Ni_{1/3}Nb_{2/3}$)$O_{3}$-0.39Pb$TiO_{3}$ (hereafter PSNNT) at the morphotropic phase boundary (MPB) composition were investigated with $0{\sim}2.5$ mot% $MnO_{2}$ doping. Bulk density, dielectric loss and tetragonality of crystal structure were all improved with increasing $MnO_{2}$ additive content. With increasing $MnO_{2}$ additive content, the electromechanical coupling factor and quality factor were also increased: Electromechanical coupling $k_{p}$ and quality factor $Q_{m}$ at 2.0 mol% $MnO_{2}$ doping with were showed highest values of 55.6 % and 252, respectively.

• Asian-Australasian Journal of Animal Sciences
• /
• 제21권8호
• /
• pp.1220-1225
• /
• 2008

This study was conducted to investigate the protective effect of genistein on the antioxidative defence system and membrane fluidity in chick skeletal muscle cells after supplementation with 0, 20, 40, and $80{\mu}mol/L$ genistein in $50{\mu}mol/L$ $FeSO_4/H_2O_2$ treated cells for 24 h. Genistein supplementation recovered the decreased activity of total superoxide dismutase induced by $FeSO_4/H_2O_2$, significantly increased glutathione peroxidase activity (p<0.05) and decreased malondialdehyde production (p<0.05). The treatment of 80 mol/L genistein in $FeSO_4/H_2O_2$ treated cells decreased the secretion of creatine kinase (p<0.05). Fluorescence polarization values and microviscosities observed with $FeSO_4/H_2O_2$ treated cells were significantly higher than those observed with no $FeSO_4/H_2O_2$ treated cells. The addition of $80{\mu}mol/L$ genistein improved the increased fluorescence polarization value (p<0.05) caused by $FeSO_4/H_2O_2$ treatment. The microviscosity value was significantly decreased by adding genistein (p<0.05). In conclusion, genistein protected skeletal muscle cells from oxidative damage by improving antioxidative status and membrane fluidity.

• 전기전자학회논문지
• /
• 제25권2호
• /
• pp.344-349
• /
• 2021

Super Junction구조는 항복전압과 온-상태 전압강하의 트레이드-오프 특성을 개선하고자 제안된 구조이다. 본 논문은 Super Junction IGBT P-Pillar 내부 영역에 Trench SiO₂를 성장시킨 구조를 제안한다. Super Junction구조에 인가되는 전계를 3D로 관찰 시 P-Pillar 내부에 전계가 인가되지 않는 영역을 확인하였다. Pillar영역의 부분저항은 각 Pillar의 크기와 항복전압에 의해 변동되는데 전계가 인가되지 않는 P-Pillar 내부 영역을 Trench 한 후 SiO₂를 성장시켜 P-Pillar의 크기를 감소시킨다. 4.5kV의 동일한 항복전압을 가질 때 온-상태 전압강하 특성이 Field Stop IGBT 대비 약 58%, 기존의 Super Junction IGBT 대비 19% 향상되는 것을 확인하였다.