• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.371-378
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• 2001

To enhance seismic performance of a structure ATC-40 and FEMA-273 propose technical strategies such as increasing strength, altering stiffness, and reducing demand by employing base isolation and energy dissipation devices. Specifically the energy dissipation devices directly increase the ability of the structure to dampen earthquake response. However nonlinear dynamic time history analysis of a structure with energy dissipation devices is complicated and time consuming. In this study a simple and straightforward procedure is developed using effective damping ratio to obtain the required amount of viscoelastic dampers in order to meet given performance objectives. Parametric study has been performed for the period of the structure, yield strength, and the stiffness after the first yield. According to the analysis results, earthquake demand and required damping ratio were reduced by installing viscoelastic dampers. The results also show that with the addition of the supplemental damping evaluted by the proposed method the performance of the model structures are well restrained within the target point.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.91-94
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• 2005

Experimental research was conducted to investigate the behavior of RC circular columns confined by high-strength ties. Large scale columns with concrete strength 34.1 and 65.3 MPa were tested under monotonically increasing concentric compression. The test parameters included the volumetric ratio, tie arrangement, tie yield strength, and concrete compressive strength. The results indicate that high-strength concrete columns can be confined to achieve inelastic deformations usually predicted for normal-strength concrete columns. This can be done by providing increasing volumetric ratio and tie yield strength.

• International Journal of Korean Welding Society
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• 제3권2호
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• pp.40-45
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• 2003

A series of experiments has been carried out to investigate the effect of titanium, boron and nitrogen on the microstructure and toughness of simulated heat affected zone (HAZ) in quenched and tempered (QT) type 490MPa yield strength steels. For acquiring the same strength level, the carbon content and carbon equivalent could be lowered remarkably with a small titanium and boron addition due to the hardenability effect of boron during quenching process. Following the thermal cycle of large heat input, the coarsened grain HAZ (CGHAZ) of conventional quenched and tempered (QT) type 490MPa yield strength steels exhibited a coarse bainitic or ferrite side plate structure with large prior austenite grains. While, titanium and boron bearing QT type 490MPa yield strength steels were characterized by the microstructure in the CGHAZ, consisting mainly of the fine intragranular ferrite microstructure. Toughness of the simulated HAZ was mainly controlled by the proper Ceq level, and the ratio of Ti/N rather than titanium and nitrogen contents themselves. In the titanium­boron added QT steels, the optimum Ti/N ratio for excellent HAZ toughness was around 2.0, which was much lower than the known Ti/N stoichiometric ratio, 3.4. With reducing Ti/N ratio from the stoichiometric ratio, austenite grain size in the coarse grained HAZ became finer, indicating that the effective fine precipitates could be sufficiently obtained even with lower Ti/N level by adding boron simultaneously. Along with typical titanium carbo­nitrides, various forms of complex titanium­ and boron­based precipitates, like TiN­MnS­BN, were often observed in the simulated CGHAZ, which may act as stable nuclei for ferrite during cooling of weld thermal cycles

• 한국버섯학회지
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• 제20권2호
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• pp.61-68
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• 2022

전라북도농업기술원이 육성한 꽃송이버섯 '너울'의 표준 생육배지 구명을 위해 톱밥과 첨가물의 종류, 배합비를 달리하여 재배특성과 수량을 조사하였다. 톱밥 종류에서는 낙엽송 처리가 재배일수 97일로 가장 짧았으며 수량 역시 143.6 g으로 우수함에 따라 꽃송이버섯 재배에 적합한 수종으로 판단된다. 첨가물 선발시험에서는 수량이 밀기울 처리에서 116.6 g으로 가장 많았고, 수율 역시 밀기울 처리에서 53.1%로 가장 높음에 따라 꽃송이버섯 생산에 적합한 첨가물로 밀기울이 적합하다고 판단된다. 낙엽송 톱밥:비트펄프:밀기울을 이용한 배합비 조성에 따른 시험 결과, 수량은 80:15:5와 85:10:5 처리에서 각각 114.4 g, 111.4 g이었고, 수율은 85:10:5 처리에서 52.5%, 80:15:5 처리에서 51.8%였으나 수량과 수율에서 두 처리간의 통계상 유의성이 없었다. 따라서 꽃송이버섯 생산에 적합한 표준 생육배지로는 낙엽송 톱밥:비트펄프:밀기울을 이용한 80:15:5 또는 85:10:5 배합비가 유리한 것으로 판단되며, 이를 통해 꽃송이버섯 재배에 적합한 C/N율은 184~223 수준임을 추측할 수 있었다. 또한, 배지의 C/N율이 105 이하일 때는 발이가 어려움에 따라 꽃송이버섯 재배에 있어서 배지 pH 외에 배지의 C/N율 역시 발이에 중요한 요인이라는 것을 알 수 있었다.

• 한국도로학회논문집
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• 제19권1호
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• pp.1-9
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• 2017

PURPOSES : The objective of this study is to develop an optimized method of mix design for rapid-set lightweight-formed mortar mix. To achieve this objective, the workability, setting time, and compressive strength of mixes under various conditions of mix design were evaluated. METHODS : The water-bonder ratio, fly-ash substitution ratio, and forming agent injection amount were selected as design variables in the study. The fluidity, setting time, density, and strength of the mortar mix were considered as major evaluation criteria of the mixture, and were subsequently utilized to evaluate the characteristics of the mortar mix under various conditions. RESULTS : The observations made from the mix design process are as follows: 1) the air content and fluidity increase as the forming agent ratio and forming agent ratio increase, respectively; 2) the maximum air content is approximately 20%; 3) the accelerating agent decreases the fluidity of the mortar mix by 15% on average; 4) the forming agent injection ratio and fly-ash substitution ratio yield significant effects on the initial and final set times of the mortar mix; 5) as the forming agent injection ratio and fly-ash substitution ratio increase, the compressive strength of the mortar mix decreases; and 6) the 28-day compressive strengths of the forming agent injection ratio and fly-ash substitution ratio yield the most significant effects. CONCLUSIONS : It is concluded that the governing design variables for the rapid-set lightweight-formed mortar mix are the forming agent injection ratio and fly-ash substitution ratio.

• 한국환경과학회지
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• 제9권6호
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• pp.449-454
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• 2000

Sustainable development has been the key concept, both in economic policies and in environmental management. On the basis of an systems ecology perspective, this suggests the sustainable development of Korea\`s natural environment and economic activity using the EMERGY evaluation. The total EMERGY use(7,730E20sej/yr) in Korea is 81 percent from imported sources, fuels and goods and services. The ratio of outside investment to attracting natural resources is already large, like other industrialized countries. Continued availability of purchased inputs at a favorable balance of EMERGY trade, currently about 2.85 to 1 net EMERGY, tis the basis for present economic activity and must decrease as the net EMERGY of purchased inputs including fossil fuels goes down. EMERGY yield ratio and environmental loading ratio were 1.23 and 20.30, respectively. The population level is already in excess of carrying capacity. Its carrying capacity for steady state on its renewable sources is only 2.2 million people, compared to 45.9 million in 1977. EMERGY sustainability index is therefore less than one, which is indicative of highly developed consumer oriented economies. Until now the development of a country has been achieved by the economic growth, but it can be sustained in the long run by the use of renewable resource systems. the efficiency of energy usage, and the transformation of the social-economic structure based on an ecological-recycling concept.

• 콘크리트학회논문집
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• 제14권1호
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• pp.110-117
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• 2002

공용하중의 증가 등에 따른 교량 바닥판의 성능향상 시 바닥판 두께, 콘크리트 강도, 철근강도 그리고 철근비와 더불어 보강재비에 의하여 바닥판의 파괴양상은 바뀌어 질 수 있다. 일반적으로 교량 바닥판의 파괴양상은 주철근 및 배력철근의 항복 이후에 펀칭전단파괴가 발생하는 것으로 나타나고 있으며, 외부부착공법을 적용함에 있어서 이러한 파괴양상을 유지해야 될 것으로 판단된다. 본 연구에서는 바닥판에 사용된 철근비 및 보강재비 등을 주요변수로 하여 항복선 이론 및 소성 펀칭모델 등을 적용한 항복강도 및 파괴강도를 해석하였으며, 철근비에 따른 임계보강재량을 제안하였다.

• Bulletin of the Korean Chemical Society
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• 제23권9호
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• pp.1229-1258
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• 2002

This paper reports the photochemical reduction of benzil 1 to benzoin 2 and the reduction of 2 to hydrobenzoin 4 in deoxygenated solvents in the presence of triethylamine (TEA) and/or TiO2. Without TEA or TiO2, the photolysis of 1 resulted in very low yield of 2. The presence of TEA or TiO2 increased the rate of disappearance of 1 and the yield of 2, which were further increased considerably by the presence of water. The photoreduction of 1 to 2 proceeds through an electron transfer to 1 from TEA or hole-scavenged excited TiO2 followed by protonation. In the reaction medium of 88 : 7 : 2 : 3 CH3CN/CH3OH/H2O/TEA with 2.5 $㎎/m{\ell}$ of TiO2, the yield of 2 was as high as 85 % at 50 % conversion of 1. The photolysis of 2 in homogeneous media resulted in photo-cleavage to benzoyl and hydroxybenzyl radicals, which are mostly converted to benzaldehyde. The reduction product 4 is formed in low yield through the dimerization of hydroxybenzyl radicals. The addition of TEA increased the conversion rate of 2 and the yield of 4 significantly. This was attributed to the scavenging effect of TEA for benzoyl radical to produce N,N-diethylbenzamide and the photoreduction of benzaldehyde in the presence of TEA. The ratio of $(\pm)$ and meso isomers of 4 obtained from the photochemical reaction is about 1.1. This ratio is the same as that from the photochemical reduction of benzaldehyde in the presence of TEA. In the TiO2-sensitized photochemical reduction of 2, meso-4 was obtained in moderate yield. The reduction of 2 to 4 proceeds through two consecutive electron/proton transfer processes on the surface of the photocatalyst without involvement of ${\alpha}-cleavage$. The radical 11 initially formed from 2 by one electron/proton process can also combine with hydroxy methyl radical, which is generated after hole trapping of excited TiO2 by methanol, to produce 1,2-diphenylpropenone after dehydration reaction.

• 한국작물학회지
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• 제51권2호
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• pp.130-136
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• 2006

Growth and quality of rice are affected by various factors including the location of cultivation. This study was conducted to investigate the effects of altitudinal locations on the growth and yield-related components of rice. Nineteen Japonica type varieties were grown at Iksan (altitude, 10 m), Imsil (altitude, 150 m), Jinan (altitude, 275 m) and Jangsu (altitude, 430 m) at a similar latitude in Jeonbuk province in the south western Korea. Minimum air temperature showed a strong negative correlation with altitude. The morphological traits and yield-and quality-related components were analyzed. Longer days to heading was required at higher altitudes. However, culm length, panicle length, panicle number, grain number and rice yield were reduced at higher altitudes. Protein content of brown rice increased but fatty acid content decreased at higher altitudes. Amylose content was affected by neither the altitude nor the ecotype. Palatability of polished rice tends to be improved at higher altitudes and in early-maturing ecotypes but its relationships with altitude and ecotype were not significant. Head rice ratio was lower at higher altitudes but broken rice ratio vise versa. These results indicate that growth and quality of rice are affected significantly by changes in temperatures at the locations of different altitude. Also, the characters related to yield and quality of rice often respond incompatibly to the changes in altitudes. These results could provide valuable information for the strategic planning of rice production in geographically diverse areas.

• 농업과학연구
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• 제42권4호
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• pp.305-311
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• 2015

In this research, we surveyed the yield change of garlic cultivation with seed bulbs according to annual field culture after induced meristem culture. From 2007 to 2013, yearly produced seed bulbs from $2^{nd}$ to $8^{th}$ generation were cultivated in the Muan field. Over the generations, the general growth characteristics such as the plant height, leaf number, leaf length and stem diameter were all decreased. When we compared the conventional seed bulbs and TCR ones, the plant height and stem diameter showed bigger difference. And the TCR seed bulbs showed a week late harvest time against the conventional ones. The yield of $2^{nd}$ generation was 72.3 g and 57.1 g for the $8^{th}$ generation. However every generation showed higher yield than conventional seed garlic's ones as 43.9 g. The yield index showed the same trend as $2^{nd}-8^{th}$ to 63% to 21%. After the tissue culture of garlics, the viral infections (OYDV and GSV) of TCR was far less than that of conventional ones. In case of LYSV, the infection ratio was 6.7% at $2^{nd}$ generation and 26% at $8^{th}$. However, the ratio was far less than that (80%) of the conventional ones.