• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.207-214
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• 2017

High voltage electric power transmitter GIS(Gas Insulated Switchgear) above 72.5kV needs to satisfy domestic Korean peninsular standard(ES-6110-0002) in KEPCO with respect to normal and special operation conditions which include internal gas pressure, dead weight, wind and seismic load. Some other requirements not described in Korean standard can be applied from other international standards such as IEC(International Electronical Committee) 62271-203 and 62271-207. The GIS is a kind of pressure vessel structure made of aluminum and filled with SF6 gas of internal pressure 0.4~0.5MPa. Finite element analysis of GIS is performed with such operational loads including seismic loading and the stability and reliability is determined according to ASME BPVC(Boiler and Pressure Vessel Code) SEC. VIII standard where the allowable stress level of the pressure vessel is suggested. The result shows that the stress of GIS is satisfied the allowable stress level and the safety factor is about 2.3 for Korean peninsular standard.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.21-28
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• 2009

A grouting method has been widely used in construction of large-scale structure to reduce permeability and reinforce the ground. If cement and grout material were not mixed well in the injection tip equipment, an opposite flow and interception state of the chemical grouting can occur. McG (Multi-mixing counterflow prevented Grouting, McG) method installed a special grouting device to allow better mixing of the grouting material(above fineness $6,000cm^2/g$) and prevent backward flow. The block of nozzle also diversify powder rate of cement. YSS (Youngil Special Silicate, YSS) that lowers $Na_2O$ and thereby increases durability was developed by gel-forming reaction material. The seepage state and unconfined compressive strength of the injection material using the special injection tip equipment was tested in this study. The results of this study showed that the uniaxial compressive strength, permeability, N-value, TCR and RQD were improved by this method. Engineering characteristics obtained by the special injection tip method will be compared with those by the other method through various field tests from now on.

• 전기의세계
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• v.24 no.4
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• pp.42-51
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• 1975

전기공학은 그 분야가 광범위하면서 세분된 여러 소분야로 구성되어 있기 때문에 이를 간단한 몇마디로 표현하기는 불가능하다. 그러나 전기기술자는 전하를 위시하여 전하간의 힘 및 전하간의 에너지 교환에 관하여 주로 관여하게 된다. 즉 전기기술자는 전기적 에너지 및 정보의 발생, 전송, 기억 및 제어를 최적화할 책임이 있고, 그 분야는 부단히 팽창일로에 있으며 변해가고 있다. 즉 학문적인 기초이론 뿐만아니라 실제 응용분야인 산업분야에서도 눈부신 발전과 변화를 가져왔다. 현대산업 및 기술구조의 질적개선은 기술 반감기의 감소, 막대한 양의 정보처리, 시스템의 대형화, 복잡화 현상을 가져왔으며 기술자체가 사회경제활동에 미치는 영향을 극대화시켰다. 그러므로 오늘날의 모든 전기기술자들은 신뢰성을 고려한 보다 넓은 의미에서의 책임을 느껴야 한다. 조국의 근대화와 방위산업육성 과정에서 중추적 역할을 담당할 이러한 전기공학분야의 중견연구원 및 기술자를 양성하는 공과대학전기공학과의 교과과정 역시 부단히 변하는 각종 환경에 적응될 수 있는 dynamic한 것이 되어야 한다. 즉 공과대학 전기공학과이 교과과정은 어떤 특정되고 고정된 기술 또는 설계에 대한 교과목으로 치우치는 것보다 수명이 길고 강력한 응용력과 창의력을 발휘하여 우리의 기술을 토착화하여 이를 우리의 것으로 만들 수 있는 것이 되어야 한다. 이러한 국내외적인 현실을 고려하여 당학회에서는 1974년도 조사연구사업의 일환으로 교과과정조사회를 구성하여 국내의 여러대학의 전기공학과 교과과정편성에 다소의 도움을 주고저 일차적인 시안으로서 다음과 같은 특징을 갖는 교과과정을 작성하였다.{3}$N$_{4}$등의 산화물 및 질화물로 대표되는 분자성 비정질 물질로서 금지대는 2eV보다 큰 세종류로 크게 분류할 수 있다. 분류할 수 있다. 한다. 단 개개의 문제에 관한 구체적인 해석 또는 검토에 관하여는 다음 기회에 미루기로하고, 우선 여기서는 당면문제로서 대처하지 않으면 안될 자동주파수제어문제및 계통의 경제운용문제만에 한정하여, 이것을 우리나라의 현상과 관련시켜 개설하고, 이들의 자동화에 관한 기본적인 문제를 간단히 적어 보겠다. 가능하다. 제작완료된 ASIC은 기능시험을 완료했으며 실제 line-of-sight(LOS) 시스템 구현에 적용중이다. 시대를 살아 갈 회원들이다. '컨텐츠의 시대'가 개막되는 것이며, 신세기통신과 SK텔레콤은 선의의 경쟁 과 협력을 통해 이동인터넷 서비스의 컨텐츠를 개발해 나가게 될 것이다. 3배가 높았다. 효소 활성에 필수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의 회수 및 재사용이 가능하게 해준다.해준다

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.189-197
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• 2007

Concrete tunnel lining must be designed to having the fireproof performance because the lining are sometimes exposed to very high temperature due to traffic accident. Such fire temperature may cause explosion of concrete, or collapse of tunnel structure. The purpose of this study is to obtain the fundamental fireproof behavior of fire resistance-engineered cementitious composites(FR-ECC) under fire temperature in order to use the fire protection material in tunnel lining system. The present study conducted the experiment to simulate fire temperature by employing 2 types of FR-ECC and investigated experimentally the explosion and cracks in heated surface of these FR-ECC. Employed temperature curve were hydro carbon(HC, ECl) criterion, which are severe in various criterion of fire temperature. The numerical analysis is carried out the nonlinear transient heat flow analysis and verified against the experimental data. The complex features of behavior in fire conditions, such as thermal expansion, plasticity, cracking or crushing, and material properties changing with temperature are considered. By the use of analytical model, the concrete tunnel subjected to fire loads were analyzed and discussed. With comparison of current concrete materials and FR-ECC, the experimental and analytical results of FR-ECC shows the better fire resistance performance than the other.

• Korean journal of applied entomology
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• v.20 no.2 s.47
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• pp.103-106
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• 1981

This experiment was carried out to investigate the vertical penetration and diffusion of fumigants for soybean disinfection in jumbo silo. The results were as follows, 1. Using the methylbromide independently as a soybean fumigant, penetration and diffusing velocity of methylbromide gas which moved from the top to the bottom through the vertica1 silo was too rapidly, it was possible to find out more 60mg/l of methylbromide gas concentration at bottom of silo within 4 hours after beginning the fumigation. And it showed the tendency of reducing methylbromide gas concentration gradually over the 10 hours from tile beginning the fumigation. 2. In case of added $CO_2$ gas to the methylbromide as a carrier is much more rapid velocity of penetration and diffusion of methylbromide gas than that of methylbromide gas independently. Therefore methylbromide gas concentration at bottom of silo was detected over the 70mg/l within 1.5 hours after beginning the fumigation.. 3. On the other hand, hence the phostoxin as a soybean fumigant was less velocity of Penetration and diffusion of the gas through the vertical silo compare to methylbromide gas, the phostoxin gas concentration couldn't detect over the 10mg/1 during the whole fumigation period at the bottomside of silo. 4. Test insects (rice weevil; sitophilus oryzae. L.) inserted at bottom of silo for examine the fumigation effect were killed completly by using the methylbromide independently and added $CO_2$ gas to methylbromide, while using the phostoxin the test insects were most alive.

• Research in Plant Disease
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• v.22 no.4
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• pp.293-296
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• 2016

In late June 2016, stalk rot symptoms were observed on five vatieties of sorghum (Sorghum bicolar) at organic paddy-upland rotation system in Anseong city, Korea. The initial symptom on stalk surfaces was red color with a dark red spot lesion. A fungus was isolated from the initial lesion, and cultured on potato dextrose agar. Size of microconidia mostly extend to $5-19{\times}2-{\mu}m$ in culture, with 0-1 septa and macroconidia extend to $29-52{\times}3-4{\mu}m$ with 4-6 septa. Pathogenicity was investigated using conidial suspension spray to seedling of sorghum. After 3 days of inoculation, the dark red lesion was produced on stalks. On the basis of mycological characteristics, pathogenicity, and internal transcribed spacer (ITS) rDNA sequence analysis, this fungus was identified as Fusarium thapsinum. This is the first report of stalk rot on sorghum caused by F. thapsinum in Korea.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.443-451
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• 2013

Acoustic emission(AE) has emerged as a powerful nondestructive tool to detect any further growth or expansion of preexisting defects or to characterize failure mechanisms. Recently, this kind of technique, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures like a huge wind turbine blade. In this study, the activities of AE signals generated from external artificial sources was evaluated and located by new developed signal mapping source location method and this test is conducted by 750 kW full-scale blade. And a new source location method was applied to assess the damage in the wind turbine blade during step-by-step static load test. In this static loading test, we have used a full scale blade of 100 kW in capacity. The results show that the acoustic emission activities give a good agreement with the stress distribution and damage location in the blade. Finally, the applicability of the new source location method was confirmed by comparison of the result of source location and experimental damage location.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.337-346
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• 2020

Traffic jam and congestion in urban areas has caused the need to improve the utility of underground space. In response, research on underground structures is increasingly being conducted. Notably, a double-deck tunnel is one of the most widely used of all those underground structures. This double-deck tunnel is separated by the middle slab into the upper and lower roadways. Both vehicle load and earthquake load cause the middle slab to exhibit dynamic behavior. Earthquake-related response characteristics, in particular, are highly complex and difficult to interpret in a theoretical context, and thus experimental research is required. The aim of the present study is to assess the stability of a double-deck tunnel's middle slab of the Collapse Prevention Level and Seismic Category 1 with regard to the presence of vibration-damping Rubber Bearings. In vibration table tests, the ratio of similitude was set to 1/4. Linings and vibrating platforms were fixed during scaled model tests to represent the integrated behavior of the ground and the applied models. In doing so, it was possible to minimize relative behavior. The standard TBM cross-section for the virtual double-deck tunnel was selected as a test subject. The level of ground motion exerted on the bedrock was set to 0.154 g (artificial seismic wave, Collapse Prevention Level and Seismic Category 1). A seismic wave with the maximum acceleration of 0.154 g was applied to the vibration table input (bedrock) to analyze resultant amplification in the models. As a result, the seismic stability of the middle slab was evaluated and analyzed with respect to the presence of vibration-damping rubber bearings. It was confirmed that the presence of vibration-damping rubber bearings improved its earthquake acceleration damping performance by up to 40%.

• Explosives and Blasting
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• v.26 no.2
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• pp.64-76
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• 2008

Bulk Emulsion blasts using mechanized charging system, which is generally used in foreign countries, have recently introduced and gradually increased in Korea. The Bulk Emulsion are safe and able to increase the charging density for improvement of fragmentation and advancement especially in tunneling, and minimizing environmental problem. Because of less toxic gas generation, the explosives are called, namely ech-friendly products. There are two kinds of Bulk Emulsion; one is for open cut and the other is for tunneling. According to features of blast sites and its purpose, the compositions are different, but the principle is the same. In this study, trial blasts using Bulk Emulsion for tunneling had executed at 10 sites in Korea. The major result of the major job-sites is the following. First of all, compared with cartridge explosive, Bulk Emulsion was able to increase its charging density up to $35{\sim}60%$, to decrease the blast holes to approximately $10{\sim}30%$ down, and the advancement was improved up to $8{\sim}20%$ and also 30% up in its fragmentation. Toxic gas production after cartridge blasting showed 34.44ppm of its CO. Bulk Emulsion, however, showed 20.13ppm, which was 58.45% production of the cartridge explosive, and NOx was below 2ppm. The mechanized charging system of Bulk Emulsion should be applied to large sized tunnel blasting, long advanced tunnel which can secure the advancement of over $4{\sim}5m$, and the sites required finishing rapidly.

• International Journal of Highway Engineering
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• v.3 no.4 s.10
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• pp.127-136
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• 2001

To increase the structural integrity of concrete box culvert good compaction by the dynamic compaction roller with bi9 capacity is as effective as good backfill materials. It is needed for effective compaction that a compaction roller closes to concrete structure with high frequency. However structural distress of the culvert could be occur due to the excessive earth pressure by great dynamic compaction load. To investigate the characteristics of Induced stress by compaction, a box culvert was constructed with changing cushion materials and compaction methods. Two types of cushion material such as tire rubber chip and EPS(Expanded Polystyrene) were used as cushion panels and they are set on the culverts before backfill construction. Laboratory test result of cushion material says that the value of dynamic elastic modulus of rubber is lesser than that of EPS. On the other hand, material damping of rubber material is greater than that of EPS. In most case, dynamic compaction rollers with 10.5 ton weights were used and vibration frequency was applied 30Hz for the great compaction energy. This paper presents the main results on the characteristics of dynamic earth pressures during compaction. The amounts of induced dynamic pressures$(\Delta\sigma\;h)$ by compaction are affected with construction condition such as compaction frequency, depth of pressure cell, distance between roller and the wall of culvert and roller direction. Based on the measured values dynamic lateral pressure on the culverts, it could be said that orthogonal direction of roller to the length of culvert is more effective to compaction efficiency than parallel direction.