• 한국세라믹학회지
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• 제43권9호
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• pp.527-531
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• 2006

In order to study the influence of post-annealing treatment on the frequency characteristics of the Li doped ZnO(Li:ZnO) FBAR(Film Bulk Acoustic Resonator) device, we investigated the material and electrical properties of Li:ZnO films in the annealing temperature range from 300 to $500^{\circ}C$. In our samples, as annealing temperature was increased, Li:ZnO films showed the improvement of high c-axis orientation and resistance value with relieved stress and low surface roughness. In addition to, the return loss in the frequency property of fabricated FBAR was improved by annealing treatment from 24.9 to 29.8dB. From experimental results, the optimum post-annealing temperature for FBAR is $500^{\circ}C$ and it can obtain excellent Li:ZnO FBAR performance with stronger c-axis orientation, smoother surface, relieved stress, and lower loss factor.

• 대한금속재료학회지
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• 제50권11호
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• pp.809-815
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• 2012

Recently, as the interest in improving energy efficiency has grown, the demand for vehicle and machine parts that are resistant in high temperature corrosive conditions and abrasive environments has increased. Pack chromizing treatment of sintered steels is a profitable method that satisfies both corrosion resistance and low friction properties. Since austenitic stainless steels have good corrosion resistance but low mechanical hardness, if they are replaced by sintered steel parts with pack chromizing treatment, all the desirable properties such as low price, easy molding, high hardness, low frictional coefficient, and high corrosion resistance, can be obtained. The higher corrosion resistance of the chromized parts over that of the austenitic stainless steels was acquired by coating chromium carbides and a thin chromium oxides layer on the surface. Moreover, the surface morphology of chromized parts, which were composed of chromium rich phases and hardened chromium carbides by diffusing and alloying, had a peak-and-valley shape so that the dimple effect by the wrinkled morphology and high hardness induced a low friction coefficient.

• Design & Manufacturing
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• 제15권3호
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• pp.7-12
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• 2021

Plastic injection molds used for rapid heating and cooling must minimize surface damage due to friction and maintain excellent thermal and low electrical conductivity. Accordingly, various surface treatments are being applied. The properties of Al₂O₃ coating and DLC coating were compared to find the optimal surface treatment method. Al₂O₃ coating was deposited by thermal spray method. DLC films were deposited by sputtering process in room temperature and high temperature PECVD (Plasma enhanced chemical vapor deposition) process in 723 K temperature. For the evaluation of physical properties, the electrical and thermal conductivity including surface hardness, adhesion and wear resistance were analyzed. The electrical resistance of the all coated samples was showed insulation properties of 24 MΩ/sq or more. Especially, the friction coefficient of high temp. DLC coating was the lowest at 0.134.

• 한국작물학회지
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• 제65권4호
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• pp.426-435
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• 2020

본 연구는 남부지방에서 찰옥수수와 콩의 2모작 직파 표준재배법 확립을 위한 기초자료로 활용하고자 찰옥수수의 유묘기 저온에 따른 생육특성 변화 및 피해양상을 조사하였으며 그 결과는 다음과 같다. 일미찰옥수수 초장은 5℃ 이하 3일 처리구부터 저해가 나타나 모든 처리구에서 22% 이상의 저해율이 조사되었다. 경태도 저온기간이 길어지고, 온도가 낮아질수록 더 짧은 것으로 나타나, 제 2엽기 5℃ 이하 5일 처리구에서 저해율이 27% 이상으로 가장 높게 나타났다. 식생지수(NDVI)에서 저해율은 제 2엽기>제 1엽기>초엽기 순으로 높게 나타났으며, 회복기 저해율에서는 제 2엽기 5℃ 이하 7일 처리구에서 25~82%로 가장 높았다. 광합성능력지수(Fv/Fm)에서도 제 2엽기>제 1엽기>초엽기 순으로 저해율이 높게 조사되었다. 특히, -3℃ 처리구의 저온처리 및 회복기에서 생육특성의 변화가 없거나, 감소하는 것으로 조사되었다. 따라서 5℃ 이하 3일부터 저온기간이 길어지고, 온도가 낮아 질수록 생장이 저해되었고, 그 피해정도는 제 2엽기>제 1엽기>초엽기 순으로 높았다. 모든 유묘기에서 -3℃ 이하에 3일 이상 노출될 경우 생육이 정지되거나, 위조고사 하였다. 한편, 본 실험은 실내에서 수행된 결과이므로 차후 재배지역 적용여부에 대한 면밀한 추가 연구가 수행되어야 할 것으로 사료된다.

• 대한의생명과학회지
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• 제9권4호
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• pp.203-207
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• 2003

Protein aggregation could be problematic as causes of diseases and hindrance in the production of useful recombinant proteins. Aggregation of mutant tryptophan synthase $\alpha$-subunits was examined by treatment with urea and at high temperature. Large amorphous aggregate seemed to appear by heat treatment, while more various aggregates in size were formed by treatment with urea at low concentration. The result indicates that different aggregate in size could be formed depending on the treatment condition, suggesting different mechanisms underlying aggregation processes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.258-263
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• 2000

River water is higher in temperature than the surrounding environment during the winter. It is highly suitable a heat source for heat pump system. Despite its suitability, however, it is not widely used, due to its fouling and corrosive nature in heat exchanger tubes of evaporator. It is designed prior-treatment system which come into direct contact with the river water, such as auto-seamer, ozone generator for bactericidal test and auto-cleaning system. And it is analyzed treatment effects for its operation. It is designed two-stage compression heat pump system using R-134a with heating load 35.16kW, ad analyzed its performance. As a result it is obtained 3.08 COP when mid-point pressure is 1,200kPa, and bypass ratio of flowing refreigerant to high-stage compressor is 25.1%

• 한국식품저장유통학회지
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• 제7권3호
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• pp.245-248
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• 2000

파쇄마늘의 녹변발생은 품종(산지)간 차이는 적었으나 파쇄전 원료마늘의 저장방법에 크게 영향을 받았다. 즉 상온 및 CA저장했던 마늘은 녹변이 없었으나 저온저장했던 마늘에서만 그 발생이 심하였다. 그리고 녹변 방지방법으로 저온저장한 마늘을 파쇄전 40$^{\circ}C$에서 1일간 열처리할 경우 녹변을 효과적으로 방지할 수 있었으며, 품종별 열처리 효과검정 결과 남해, 서산 및 단양마늘 모두 녹변이 방지되었다. 열처리에 따른 마늘의 품질변화는 40$^{\circ}C$에서 1일간 처리에서 중량감소 및 맹아율 변화가 적었고, 유효성분의 평가지표로 이용되는 enzymatic pyruvic acid함량 변화도 적었다.

• Journal of Plant Biology
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• 제38권4호
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• pp.373-380
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• 1995

$25^{\circ}C,\;100\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$의 광량 조건에서 25일 동안 키운 고추의 제 1엽에서 광억제를 유도하였다. $25^{\circ}C에서\;0~3000\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$의 광량으로 0~70분 동안 처리하여 얻은 photon exposure [mol photons.m-2, 광량과 빛 조사 시간의 곱, Bell과 Rose (1981)]에 대한 산소 발생의 광양자 수율과 QA 환원의 광화학 효율(형광 파라미터 Fv/Fm)을 조사하여 광계II 기능의 변화를 조사하였다. Photon exposure가 증가함에 따라 산소 발생의 광양자 수율은 곡선적으로, Fv/Fm은 일치 직선형으로 감소하였는데, 각각은 $5.5\;mol\;photons{\cdot}m^{-2},\;10\;mol\;photons{\cdot}m^{-2}$에서 광계II의 활성이 50% 감소하였다. 저온($15^{\circ}C$)과 고온($45^{\circ}C$)에서 광합선능을 조사하였을 때 저온에서는 광양자수율과 Fv/Fm 비율의 변화가 거의 없었으나 고온에서는 이들의 감소가 뚜렷하게 일어났다. 그러나 빛과 온도를 함께 처리하였을 경우, 저온과 고온조건 모두에서 현저한 광억제가 일어났다. 이로 미루어 보아 저온과 고온에서 나타나는 광억제의 촉진 현상은 서로 다른 메카니즘을 통해 일어나는 것으로 사료된다.

• 한국농공학회지
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• 제40권4호
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• pp.77-84
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• 1998

Adsorption and leaching characteristics of the artificial soils produced from water and wastewater treatment sludges were examined. The batch adsorption test and TCLP leaching test were used, and constituents of interest were heavy metals and nutrients. As, Cr, Cu, Pb, and Cd were analyzed for metals, and nitrogen and phosphorus were analyzed for nutrients. All the artificial soils showed strong adsorption and low leaching for the heavy metals, which implies that the artificial soils may not be hazardous to the environment due to heavy metals and even they can be utilized effectively to remove metals in solution like mine and industrial wastewaters. This is quite promising result because in most case heavy metals are the most concern in the application of sludge product to the farmland. For the nutrients, generally, artificial soils showed high adsorption and low leaching except artificial soil from wastewater sludge produced by low temperature firing. The artificial soils produced from water treatment sludge were active in adsorbing nutrients and showed low leaching that they can be practically used to remove nutrients in advanced treatment process of the wastewater. The artificial soils produced from wastewater treatment sludge were less active in adsorbing nutrients and showed high teaching. However, they could be used usefully if applied properly to the plant growing because of their fertilizing effect. Based on the test results, overall, the artificial soils were thought to be not hazardous to the environment and they could be more useful if applied properly.

• 열처리공학회지
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• 제26권6호
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• pp.306-316
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• 2013

Microstructure and fracture behavior of a multi-phase low-density steel were investigated. After hot-rolling and heat treatment, the microstructure of low-density steel was composed of coarse ferrite grains and elongated bands which include second phases such as austenite, martensite and ${\kappa}$-carbide depending on holding time during isothermal heat treatment. After tensile test, microcracks were observed at martensite or ${\kappa}$-carbide interface in the elongated bands. Coarse ferrite grains showed cleavage fracture behavior regardless of second phase. The cleavage fracture of ferrite could be attributed to their coarse grain size and solute atoms that increase ductile-to-brittle transition temperature of ferrite. Despite of the tendency of cleavage fracture in coarse ferrite grains, a specimen having coarse spheroidized ${\kappa}$-carbide particles in the elongated bands showed high total elongation of 30%. Thus, the easiness of plastic deformation in the elongated band seems to play an important role in retardation of cleavage crack formation in coarse ferrite grains.