• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.6-14
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• 1980

One of the physiological disease, sudden wiliting of Yushin variety suggested that low sunlight, excessive nitrogen application, and highly reduced soil condions either singly or combined, might be possible causes of the disorder. Some visual symptom of sudden wilting are discoloration of leaves, development of nodal roots above the soil surface, total root rot, and lodging. Those observations led to the hypothesis that suffocation of root tissues was a direct cause of the wilting. The oxygen transport characteristics of Yushin, IR262 and Tongil were examined by two methods. First, Soil-cultured plants of the three varieties were subjected to paraffin treatment to decrease the oxygen supply from the air to root tissues through the soil-water system, liquid paraffin was applied to the water surface in the pots at panicle formation stage. In this experiment, sudden wilting was observed of Yushin and IR262 at about a week after the treatment, but Tongil remained green and healthy. Wilting-resistant variety Tongil had higher oxygen release, whereas the susceptible Yushin and IR262 had lower oxygen release. Second, the number and size of the air spaces in each internode were investigated in the 5th internode from the top, all three varieties have a similar number of air spaces, although the air spaces of Thongil were larger. In the 4th internode, Tongil had plenty air spaces, Yushin and one of the Yushin's parents IR262 had scanty or none. The observations indicated that the ability of Yushin and IR262 for oxygen transport is very limited compared with that of Tongil. The limited oxygen supply due to poor development of air space in internode of rice plants may cause suffocation of root tissues, weaken metabolic activity of the tissues, and induce root rot, subsequently inducing sudden wilting and lodging under unfavorable weather, soil and cultural conditions.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.137-139
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• 2006

단 1차형 영구자석 선형 동기 전통기(PMLSM)는 디텐트력과 단부력에 의한 큰 토크 리플을 갖는 문제점이 있다. 본 논문에서는 영구자석 선형 통기 전동기의 디텐트력을 줄이기 위해 영구자석의 극수와 전기자의 슬롯수의 비를 변경한 새로운 구조의 단 1차형 영구자석 선형 동기 전동기를 제안하였으며, 단부력을 줄이기 위하며 고정자의 길이 조정 및 챔퍼링을 통하여 영구자석 선형 동기 전동기를 설계하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.177-186
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• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.

• Microbiology and Biotechnology Letters
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• v.7 no.1
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• pp.23-30
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• 1979

Fungi which produce red pigment were isolated from tapioca chips, Korean Koji, air, and plant leaves. Among the Fungi, T-1 strain was selected as test strain. This strain was identified as a Monatcus sp. by the morphological propeties. Various culture conditions, and physical and physiological characteristics of red pigment were studied. According to the studies of culture conditions, optimum condition was found to be pH 6.5; 4 days of incubation; temperature, 32~33 c: 3.5％ of Tapioca chips powder as carbon source, 0.2％ of sodium nitrate as nitrogen source and 100 ml of medium in the 500 ml Erlenmyer flask at a rotary shaker (rpm180) as aeration condition. Also effective levels of vitamins, amino acids and inorganic compounds was found to be l$\mu\textrm{g}$/ml of folic acid and niacin; 0.3％ of L-arginine, L-glutamic acid and L-proline; and 0.001％ of manganese dioxide giving good results.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.128-143
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• 1994

At 5 DAS/T, leaf primordia of rice stems that were grown under dry condition in transverse sections were strongly stained while those under water condition had many aerenchyma cells well developed. On the other hand, leaf primordia and large air spaces in stem of transplanted rice were well developed. Rice in leaf anatomy had small and fine epidermal cells, chlorophyllous mesophylls, and bulliform cells but had no chlorophyllous vascular bundle sheath cells, while barnyardgrass leaf had large, rough and irregularly arranged epidermal cells, chlorophyllous vascular bundle sheath cells, and non-bulliform cells but had no chlorophyllous mesophylls. Epidermal cells of transplanted rice, however, were well developed, differentiated and sclerified. Cross sections of rice root under dry condition showed cell contents, regularly arranged cells, non-intercellular spaces and non-aerenchyma while under water condition had well-developed intercellular spaces, aerenchyma cells, small and densely arranged epidermis, sclerified exodermis and sclerenchyma cells. But root anatomy of transplanted rice consisted of finely, regularly arranged epidermis, well-developed intercellular spaces and nucleous cells.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.294-300
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• 1983

This study was aimed at finding out the effect of soil conditioners on soil structural properties, soil water movements and soil losses. Sandy loam and silt loam soils were treated with two different kinds of soil conditioners, hydrophobic Bitumen 0.4% or hydrophilic Uresol 0.6%, and then various physical characteristics of the treated and untreated aggregates were determined. The results are summarized as follows: 1. By the soil conditioner treatment, Bitumen 0.4% or Uresol 0.6%, the aggregate stability was increased to 1.650-3.450 as compared to 0.275-0.417 of untreated soil and the sedimented bulk density was decreased. 2. Air-water permeability ratio of sandy loam was decreased to 2.2 by Uresol treatment as compared to untreated soil 3.8. In case of silt loam, it was decreased to 6.9 and 5.3 by Bitumen and Uresol treatment as compared to untreated 9.4, and water permeability of treated soil continued high value for 40 days. 3. Air-water permeability ratio was sharply enhanced as the structure instability index increased, but the ratio increased very smoothy after the index over 1. 4. The soil moisture retention was increased 2 to 6% by Uresol treatment, but it was decreased 1 to 3% by Bitumen treatment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.7 no.2
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• pp.25-30
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• 2001

Corrugated board is composed of cellulose fibers which are arranged with the same direction as the board manufactured. The direction is classified with machine direction (MD) and cross-machine direction (CD). Therefore, corrugated board is orthotropic material that has totally different strength properties at each direction and especially, at machine direction, the mechanical properties of fiberboard is superior. The compression strength of the corrugated fiberboard boxes is very important information to the manufacturers and the end users. This study was carried out to design the optimum pattern, size, and location of ventilating hole for ventilating container through the finite element analysis. The optimum pattern and location of ventilating and hand hole were vertical oblong, a short distance to the right and left from the center of panel, and center or a short distance to the top of both sides, respectively. We identified the effect on both stress dispersion and stress level from the analysis of redisigned hand hole.

• Proceedings of the Korean Society of Community Living Science Conference
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• 2003.11a
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• pp.152-152
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• 2003

본 연구의 목적은 고추 수확과 같은 여름철 농작업 시 농민의 온열 스트레스 경감을 위한 피복 장비 개발 연구의 일환으로 두 종류의 기능성 모자를 개발하고 그 성능을 비교 검토하는 것이다. 피험자로는 건강한 남자 대학생 열 두 명이 참가하였다. 인공기후실 실험 조건은 네 가지로 모자를 쓰지 않은 경우 (Control), 챙이 넓은 시판 농작업모를 착용한 경우 (Hat A), 반사 소재의 냉각 모자를 착용한 경우 (Hat B), 반사소재이면서 통기 구조를 갖는 냉각 모자를 착용한 경우 (Hat C)이다. 인공 기후실 내 환경 조건은 기온 33$\pm$0.5$^{\circ}C$, 습도 65$\pm$5%RH, 복사 온도 39$\pm$1$^{\circ}C$로 WBGT 33$^{\circ}C$를 유지하였고, 피험자들은 120분(50분 작업, 10분 휴식, 50분 작업, 10분 휴식) 동안 모델화된 고추 수확 작업을 수행하였다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.344-347
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• 2003

본 조사를 통해 토양오염유발시설 중 유류 유출사고가 잦은 주유소에서의 오염현황 조사방법과 오염토양에 대한 적정한 정화기법을 제시하고자 하였다. 오염현황 조사결과, 지층구조 는 전반적으로 Clay로 구성되어 있으나 오염토양 주변은 비교적 투수도와 통기성이 우수한 Silty Sand층을 나타내고 있었다. 본 주유소의 경우 주유기 주변(상층부)과 지하유류저장탱크 주변(수직분포)에 오염이 분포되어 있고, 오염원인은 주유기의 배관 파손 및 결함에 의해 발생한 것으로 예상된다. 본 조사지역에 대한 정화기법으로는 토양증기추출기술(SVE)과 불포화대를 생물학적으로 복원할 수 있는 바이오벤팅기술을 결합시킨 Bioslurping이 효과적일 것으로 평가된다. 또한 Bioslurry injection treatment를 병행하여 효과적으로 고농도의 오염토양을 처리하는 것이 바람직할 것으로 판단된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.491-497
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• 2017

In recent years, 3D printing has received increasing attention due to its potential for direct fabrication beyond the traditional rapid prototyping. 3D printing has the advantage of being able to manufacture complicated shapes that were thought impossible to produce by traditional manufacturing processes. This advantage has driven applications of 3D printing to direct manufacturing of functional parts, such as lightweight structures and component integration. In this study, a porous shell structure is designed for the purpose of weight reduction and ventilation. Finite element (FE) analyses are performed to compare the effective stiffness of the porous structure with the conventional solid structure. Structural reinforcements are also considered in order to make up the stiffness reduction due to the porosity, and the relevant FE analyses are performed to investigate the effect of the reinforcement design on the bending stiffness. The optimized reinforced structure is then proposed through response surface analysis.