• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.543-551
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• 1985

A new class of polyhydrazones has been synthesized by the solution polycondensation from equimolecular amounts of aromatic dialdehydes such as para, meta, ortho-phthal aldehyde, 5,5'-methylene-bis-salicyl aldehyde (PPTA, MPTA, OPTA, MBSA) and dihydrazides, 5,5'-methylene-bis-salicylic dihydrazide (MBSDH), terephthalic dihydrazide (TDH), sebacic dihydrazide (SDH) in DMF-$CH_3COOH$ solution. The solubility characteristics, spectral, and thermal properties of the synthesized polyhydrazones and their metal chelates were also studied. These polyhydrazones and their metal chelates except the polyhydrazone prepared from OPTA-MBSDH were generally insoluble in common organic solvents. The thermogravimetric analysis of polyhydrazones showed 10% weight losses at 250∼350$^{\circ}$C and residual weight at 500$^{\circ}$C were 32.5∼62.5%. The decomposition temperature of higher relatively, and the metal chelates decrease in the following orders; Zn(II)-IIa > Ni(II)-IIa > Co(II)-IIa > Cu(II)-IIa.

• Food Industry
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• s.99
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• pp.32-37
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• 1989

양질의 국산 생강엑기스 제조기술 개발을 위한 본 연구결과를 요약하면 다음과 같다. 1) 본 연구에서 시료로 사용한 생강은 전라북도 봉동산과 충청남도 서산산이며, 이들 건강은 수분이 약$10\%$, 회분 $8\~9\%$, 조지방 $4\~5\%$이다. 2) 생강엑기스의 유효성분들은 건강입자에 내포되어 있는 상태에서 추출 속도는 반응층을 통한 확산모델로 설명된다. 침출 효율을 개선하기위해서는 다음과 같은 조건이 필수적이다. 3) 건강의 입자는 $10\~20{\mu}m$정도의 전분입자가 될수록 많이 노출되도록 160목을 통과하는 작은 입자로 분쇄하면 추출효율은 최대화 할 수 있다. - 추출온도는 엑기스의 주요성분의 손실이 무시되는 최대온도, $40^{\circ}C$가 최적이다. - 160목, $40^{\circ}C$에서 추출시간 3-4시간이 최적이다. - 이같은 조건에서의 엑기스 회수율은 약 $8\%$이다. 4) 엑기스내의 비자극성 성분은 회분 $0.5\~0.8\%$, 조지방 $1.2\~1.8\%$, 조단백 $2.8\~3.5\%$이고, 유리당은 거의 침출되지 않는다. 엑기스내의 주요 지방산은 Linoleic acid가 가장 많이 함유되어 있다. 5) 기계건조보다 일광건조에 의한 건강에서 추출된 엑기스의 품질이 양호하며, 외국산 고급 엑기스와 품질면에서 대등한 것이다. 6) 위와 같은 결과는 TLC로 분리하고 분리된 각 Spot를 HPLS로 분석, IR, NMR, LC/MS를 사용하여 주요성분을 확인 및 정량화하였다. 이로부터 엑기스내의 주요성분은 gingerol이 약 0.38, Shogaol이 약 0.027, 그리고 Paradol이 0.03의 농도분율을 가지고 있음을 알았다. 7) 기계건조 건강으로부터 얻은 엑기스는 상온 $\~100^{\circ}C$ 범위에서 휘발 및 열분해에 의한 무게감량이 양건강에 비해 약 2.7배나 높다. 그러므로 생강엑기스를 사용하여 제조되는 생강차 제조시 열풍건조($60^{\circ}C$, 30분)는 품질에 지대한 영향을 미친다는 것을 발견하였다. 8) 생강엑기스 제조는 건강 재배방법 저장기간과 방법, 건조방법이 건강특성을 좌우한다. 9) 본 연구에서 제시된 열분석(DSC와 TGA)방법을 도입한다면 신속하고 경제적으로 생강 엑기스 품질을 평가하는 데에 큰 기여가 있을 것으로 생각된다. 10) 양호한 생강차를 만들 수 있다고 선정된 엑기스는 수입 엑기스와 함께 양건강의 제품이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.1011-1019
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• 2015

Insulated-gate bipolar transistors (IGBTs) are the predominantly used power semiconductors for high-current applications, and are used in trains, airplanes, electrical, and hybrid vehicles. IGBT power modules generate a considerable amount of heat from the dissipation of electric power. This heat generation causes several reliability problems and deteriorates the performances of the IGBT devices. Therefore, thermal management is critical for IGBT modules. In particular, realizing a proper thermal design for which the device temperature does not exceed a specified limit has been a key factor in developing IGBT modules. In this study, we investigate the thermal behavior of the 1200 A, 3.3 kV IGBT module package using finite-element numerical simulation. In order to minimize the temperature of IGBT devices, we analyze the effects of various packaging materials and different thickness values on the thermal characteristics of IGBT modules, and we also perform a design-of-experiment (DOE) optimization

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.331-339
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• 2003

The study discussed in this paper investigated the material characteristics for the Thermo-Mechanical Control Process(TMCP) plates, which are controlled by several factors such as rolling, cold-stripping, cooling rate, and fixed carbon quantity. The suitability of thick TMCP steel plates as structural steel was also estimated through several experiments and with the us of a statistical method to analyze mill certificate sheets provided by the manufacturer. The results of this study are as follows: the TMCP steel plates showed stable values of the composition parameter ($P_cm$) and the carbon equivalents ($C_eq$ ) with satisfied yield strength, ultimate strength, and low-yield ratio.

• Korean journal of food and cookery science
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• v.21 no.4 s.88
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• pp.406-415
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• 2005

To evaluate the storage characteristics of Korean soups for the utilization of the Ready-Prepared Foodservice System, Yukkaejang(spicy beef and vegetable soup), Sagol-woogeojitang (bone soup with young cabbage), Kalbitang(beef short-ribs soup) and Seolleongtang(beef and bone soup) were prepared and their physico-chemical characteristics were investigated according to storage time and temperature$(4^{\circ}\;to\;20^{\circ}C)$ through analysis of pH, TBA values, Hunter color values, microbial counts, and sensory evaluation. No significant difference in pH was shown among the 4 kinds of soup while TBA values were significantly increased with storage time and temperature. Hunter color values(L, a and b values) of the Korean soups were significantly increased except Yukkaejang. In the sensory evaluation, appearance, color, flavor, taste, texture and overall acceptability of the soups decreased significantly with increasing storage time and temperature. Through correlation analysis between quality factors of treatments stored at $4^{\circ}$, the overall acceptability in Yukkaejang and Seolleongtang showed significant positive correlation with appearance, color, flavor and texture. The evaluated shelf-life of all four Korean soups was within 3 days at $10^{\circ}$, suggesting that Korean soups are applicable to ready-prepared foodservice system.

• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.4
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• pp.19-28
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• 2020

The Urban Heat Island (UHI) Effect has intensified due to urbanization and heat management at the urban level is treated as an important issue. Green space improvement projects and environmental policies are being implemented as a way to alleviate Urban Heat Islands. Several studies have been conducted to analyze the correlation between urban green areas and heat with linear regression models. However, linear regression models have limitations explaining the correlation between heat and the multitude of variables as heat is a result of a combination of non-linear factors. This study evaluated the Heat Island alleviating effects in Seoul during the summer by using a deep neural network model methodology, which has strengths in areas where it is difficult to analyze data with existing statistical analysis methods due to variable factors and a large amount of data. Wide-area data was acquired using Landsat 8. Seoul was divided into a grid (30m × 30m) and the heat island reduction variables were enter in each grid space to create a data structure that is needed for the construction of a deep neural network using ArcGIS 10.7 and Python3.7 with Keras. This deep neural network was used to analyze the correlation between land surface temperature and the variables. We confirmed that the deep neural network model has high explanatory accuracy. It was found that the cooling effect by NDVI was the greatest, and cooling effects due to the park size and green space proximity were also shown. Previous studies showed that the cooling effects related to park size was 2℃-3℃, and the proximity effect was found to lower the temperature 0.3℃-2.3℃. There is a possibility of overestimation of the results of previous studies. The results of this study can provide objective information for the justification and more effective formation of new urban green areas to alleviate the Urban Heat Island phenomenon in the future.

• Journal of Gifted/Talented Education
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• v.23 no.5
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• pp.731-750
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• 2013

Conceptions toward the artistically gifted were investigated through analyzing newspaper articles from 5 major newspapers for 14 years beginning from 1999 to 2013. There were a total of 1,281 articles having to do with artistically gifted, and showed a steady increase in number of articles as the years went by. Largest number of articles were about musically gifted, and an increase in number of articles were observed following new implementations in law and policy. Implications for education and policy development for the artistically gifted are discussed.

• Journal of the Korean Geotechnical Society
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• v.36 no.8
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• pp.49-60
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• 2020

A fully coupled thermo-hydro-mechanical model is established to evaluate frost heave behaviour of saturated frost-susceptible soils. The method is based on mass conservation, energy conservation, and force equilibrium equations, which are fully coupled with each other. These equations consider various physical phenomena during one-dimensional soil freezing such as latent heat of phase change, thermal conductivity changes, pore water migration, and the accompanying mechanical deformation. Using the thermo-hydro-mechanical model, a sensitivity analysis study is conducted to examine the effects of the geotechnical parameters and external conditions on the amount of frost heave and frost heaving rate. According to the results of the sensitivity analysis, initial void ratio significantly affects each objective as an individual parameter, whereas soil particle thermal conductivity and temperature gradient affect frost heave behaviour to a greater degree when applied simultaneously. The factors considered in this study are the main factors affecting the frost heaving amount and rate, which may be used to determine the frostbite sensitivity of a new sample.

• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.31-39
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• 2021

The modular construction method is an off-site construction method using built-in structures from the manufacturing facilities. Modular construction is commonly applied to buildings which have relatively smaller and simpler structures than other types of buildings. Although modular building has emerged in the domestic construction industry as an alternative building strategy, previous researches on the environmental characteristics of modular building has not been comprehensively studied. Thus, this study empirically analyzed the insulation performance of thermal bridge and condensation parts of the modular buildings by using IR image analysis, Air-Surface Temperature Ratio method, and temperature difference ratio. The insulation performance analysis was conducted by comparing a modular building and a RC building in Seoul. The results shows that there was no significant difference between insulation performances of RC building and modular building. Furthermore

• Analytical Science and Technology
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• v.24 no.4
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• pp.256-265
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• 2011

Ambers have been used as a gemstone and a religious object since the ancient times and found in several archaeological sites in Korea. To prepare an enhanced conservation measures, we surveyed the chemical and spectroscopic properties of the ambers according to the provenance. Total 14 amber samples were collected from 6 different provenances including Baltic, Chiapas, Colombian, Dominican, Fushun and Madagascar amber. Infrared (IR) spectroscopic analysis was conducted for the non-destructive examination of the amber samples. They were also analyzed with pyrolysis/GC/MS (py/GC/MS) at the pyrolysis temperature of $300^{\circ}C$ with the on-line derivatization to trimethylsilyl ester. Baltic shoulder corresponding to the absorption at $1250cm^{-1}{\sim}1150cm^{-1}$ appeared in the IR spectrum of Baltic amber. IR spectra of the other ambers also showed somewhat distinctive characteristic peaks. In py/GC/MS analysis peaks assignable to succinic acid, dehydroabietic acid and pimaric acid were detected, which are known to be the components of the amber. In the meanwhile, the presence of compounds appearing in certain amber will be applied to differentiate the provenances of amber relics if their fragments are available for the analysis. These results are expected to help the confirmation of archaeological amber relics and archaeometric interpretation of provenances and manufacturing techniques.