• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.3
• /
• pp.211-221
• /
• 2009

With recent trends of super-tallness, atypical plan shapes and zoning constructions in high-rise buildings, a structural stability of the building under construction is arising as a key issue for design and construction plan. To ensure the structural stability under construction, the differential column shortening of vertical members, the lateral displacement of tower frames, and differential settlement of raft foundation by unbalanced distributions of a tower self-weight before the completion of a lateral load resisting system should be checked by construction sequence analysis, which should be performed by systematic combinations with structural health monitoring, construction compensation program, and construction panning. This paper presents the scheme of zone-based construction sequence analysis by using the existing commercial analysis program, to check the stability of high-rise building under construction. This scheme is applied to 3-dimensional structural analysis for a real high-rise building under construction. The analysis includes real construction zoning plans and schedules as well as creep and shrinkage effects and time-dependent properties of concrete. The simplified construction sequence and assumed material properties were continuously updated with the change on construction schedule and correlations with in-situ measurement data.

• Journal of Radiation Protection and Research
• /
• v.21 no.1
• /
• pp.1-7
• /
• 1996

In this paper, we discussed the fabrication and characterization of bulk type CdZnTe detector for pocket surveymeter. The resistivity of CdZnTe single crystal grown by the High Pressure Bridgman method is in the mid of $10^9$ ohm-cm. The detector structure is Au/CdZnTe/Au and gold electrode is formed by electroless deposition method. Resolutions of 4.8keV and 2.2keV were observed at 22.2keV line of $^{109}Cd$ and 59.6keV line of $^{241}Am$ at room temperature, respectively. We also constructed the small size pocket surveymeter using home made CdZnTe detector. It shows the good linearity over a range from 1mR/hr to 10R/hr with deviation less than 5%. The sensitivity of the surveymeter developed is $2.2{\times}10^3 cps/Rad\;hr^{-1}$ for the 662keV of $^{l37}Cs\;{\gamma}-ray$.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.2 no.4
• /
• pp.1-9
• /
• 1982

Variation of soil properties is studied by permeating injection of chemical grouts, such as cement type, water-glass type and acrylamide type, to the same soil samples with different densities. Moreover, injection tests using specially prepared equipments of 1.0 shot system and 1. 5 shot system are attempted to investigate permeating injection effects in highly compacted soil and in the presence of ground water. The main factor which causes the improvement of cut-off effect and shearing strength is the cohesion of soil. The strength in the loose state is fundamentally governed by the membrane cohesion, meanwhile, in the loose state is governed by the structural cohesion. Injection effects under the ground water flow is considerably decreased, and effective gelling ratio of approximate 45~80% is observed by variation of velocity and gel time, besides grading of injection materials has high relation with permeation and traveling length but has little relation with effective gelling ratio. Permeating injection effects, such as gelling scope, gelling strength in highly compaoted soil conditions can be confirmed by penetration resistance diagram and iso-strength curve.

• Journal of Life Science
• /
• v.27 no.6
• /
• pp.661-672
• /
• 2017

Endophytic fungi are present in host plants and contribute to resistance to biotic and abiotic stress. Aquatic plants are living in aquatic environment such as saltwater or freshwater and exposed more water stress than other land plants. In this study, we investigated 4 wetlands in Jeju and collected 11 aquatic plants. Exogenous microbes were removed by preprocessing of plants and endophytic fungal strains were isolated from the plants. We isolated 126 fungal strains from Namsaengi-pond, 22 fungal strains from Sujangdong-marsh, 44 fungal strains from Yongsu-reservoir and 32 fungal strains from Gangjeongcheon. The fungal strains were identified using internal transcribed spacer (ITS) region and analyzed the phylogeny and diversity. Endophytic fungi isolated from plants of Namsaengi-pond were classified to 30 genera, 19 families, 12 orders, 7 classes and 4 phyla. Endophytic fungi of Sujangdong-marsh were classified to 11 genera, 11 families, 6 orders, 5 classes and 4 phyla. Endophytic fungi of Yongsu-reservoir were classified to 13 genera, 12 families, 7 orders, 5 classes and 4 phyla. Endophytic fungi isolated from Gangjeongcheon were classified to 9 genera, 7 families, 5 orders, 2 classes and 1 phyla. Overall, they were divided 40 genera and Alternaria, Colletotrichum and Fusarium were isolated from 4 sites in common. By investigating the endophytic fungi in aquatic plants, it is for baseline data that determination of diversity and the ecological distribution of endophytic fungi.

• Pediatric Infection and Vaccine
• /
• v.15 no.2
• /
• pp.146-151
• /
• 2008

Purpose : Multidrug-resistant Acinetobacter baumannii (A. baumannii) is recognized to be the most difficult pathogen to control and treat in pediatric burn centers. We analyzed the antibiotic susceptibility pattern of A. baumannii in our pediatric burn intensive care unit during the past 7 years. Methods : We retrospectively evaluated 56 patients (105 samples) under the age 15 years and who were infected with A. baumannii between January 1999 and December 2005. Results : Fot the 56 patients, the ratio of males to females was 1.15:1 and the median age was 48.3 months. The sites of 105 isolates were wounds (65%), sputum (20%), blood (6 %), cutdown tips (5%), endo-tip tubes (2%) and urine (2%). A. baumannii presented yearround. The annual antimicrobial resistance rate increased and the multidrug resistant rate for two or more antibiotics was 93.33%. For 3 patients in whom resistance emerged, the interval period between the susceptible and resistant strains after antibiotic use was a mean of 10 days. The A. baumannii isolated from blood were all multi-drug resistant pathogens. Conclusion : Multidrug resistance of A. baumannii is increasing. Strict infection control guidelines and active surveillance are needed for the prevention and treatment of A. baumannii in hospitals.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.22 no.3
• /
• pp.275-283
• /
• 2002

To detect the position and depth of buried underground utilities, method of Ground Penetrating Radar(GPR) survey is the most commonly used. However, the skin-depth of GPR is very shallow, and in the places where subsurface materials are not homogeneous and are compose of clays and/or salts and gravels, GPR method has limitations in application and interpretation. The aim of this study is to overcome these limitations of GPR survey. For this purpose the site where the GPR survey is unsuccessful to detect the underground big pipes is selected, and soil tests were conducted to confirm the reason why GPR method was not applicable. Non-destructive high-frequency electromagnetic (HFEM) survey was newly developed and was applied in the study area to prove the effectiveness of this new technique. The frequency ranges $2kHz{\sim}4MHz$ and the skin depth is about 30m. The HFEM measures the electric field and magnetic field perpendicular to each other to get the impedance from which vertical electric resistivity distribution at the measured point can be deduced. By adopting the capacitive coupled electrodes, it can make the measuring time shorter, and can be applied to the places covered by asphalt an and/or concrete. In addition to the above mentioned advantages, noise due to high-voltage power line is much reduced by stacking the signals. As a result, the HFEM was successful in detecting the buried underground objects. Therefore this method is a promising new technique that can be applied in the lots of fields, such as geotechnical and archaeological surveys.

• The Journal of Engineering Geology
• /
• v.17 no.2 s.52
• /
• pp.205-215
• /
• 2007

In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas. Also, the relationship with landslides and interrelation with each soil properties are analyzed. The landslides in three areas with different geological condition are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. However soil characteristics have a little differentiation to geological condition, the soils sampled from landslide area have higher proportion of fine particle and porosity, and lower density than those from non landslide area. In case of same geological condition, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. The soil layer with high internal friction angle is more stable than that with low internal friction angle in all geological condition. The permeability is mainly influenced by effective particle size, coefficient of uniformity, coefficient of gradation, porosity, density and so on. Also, those have interrelation with each factor. These interrelations are similar in all study area. Meanwhile, in proportion as the void ratio and the porosity rises the permeability increases.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.27-27
• /
• 2010

청정에너지원의 수요가 증가함에 따라 에너지원의 공급로의 역할을 하는 강관의 수요가 증가하고 있다. 소재가공 기술의 발전과 함께 경량의 고장력 강재의 적용은 공급로의 역할을 하는 강관의 비용절감 및 자원의 효율적 이용 측면에서 지속적으로 연구 개발을 이어왔다. 이러한 추세에 따라 구조용 또는 라인파이프용 강관에서도 고장력 강재의 적용과 함께 고인성 그리고 용접성의 향상을 위한 다양한 라인파이프용 강재의 개발과 이의 적용이 그간 활발히 진행되어왔다. 용도상 반드시 필요한 특성인 고장력, 고인성, 용접성 등 외에도 다양한 강재의 사용에 따른 제조공정상 즉 용접공정에서 발생될 수 있는 용접부의 기계적 특성 변화에 대한 특성 연구 및 기술 연구가 계속 되어왔다. 주로 강관을 생산하는데 쓰이는 ERW (Electric Resistance Welding) 공정에서도 이러한 문제점을 해결하기 위해 많은 연구가 진행되고 있다. ERW는 높은 생산성과 낮은 제조비용의 장점을 가지고 있으나 용접 후 용접부의 기계적 특성 감소로 인한 단점이 있다. 때문에 기계적 특성향상을 위해 최적의 용접조건에 대해 연구해야 할 필요가 있다. 본 연구에서는 4가지 합금강관의 ERW 용접시 용접 입열량의 변화와 용접부의 후열처리를 통한 미세조직의 변화와 기계적 특성에 대해서 고찰하였다. 4강종 시편의 미세조직을 OM, SEM을 통한 분석 이후 인장시험 및 경도시험 등을 통해 기계적 특성을 평가하였다. 대부분의 시편에서 입열량의 증가에 따라 Ferrite 분율이 증가하였고 용접중앙부의 Ferrite 양이 용접경계부 보다 많았다. Ferrite 집중부의 분포가 극명하게 관찰되었던 DP780 (적정) 강종과 미세하게나마 Ferrite 집중부가 존재하였던 K55 (과소, 과대) 강종에서 나란히 경도 하락 현상이 관찰되었다. 이는 강종마다 고유의 Ceq, 합금 중 Mn 농도, 입열량 등에 의한 복합적인 이유 때문으로 판단된다. 탄소가 0.3~0.4 wt% 함유된 중탄소강인 S45C, K55의 경우 용접중앙부와 용접경계부의 페라이트 분율 차이가 큰 것을 알 수 있었다. 이는 용접시 열에 의한 탈탄현상으로 인해 나타나는 현상으로 판단된다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.10
• /
• pp.712-720
• /
• 2001

Algorithms from the research of the layout migration were proposed in the paper. These are automatic recognition algorithm for the VLSI devices from it, graph based construction algorithm to maintain the constraints, dependencies, and design rule between the devices, and high speed compaction algorithm to reduce size of the VLSI area and reuse the design with compacted size for the new technology. Also, this paper describes that why proposed algorithms are essential for the era of the SoC (System on a Chip), design reuse, and IP DB, which are the big concerns in these days. In addition to introduce our algorithms, the benchmark showed that our performance is superior by 27 times faster than that of the commercial one, and has better efficiency by 3 times in disk usage.

• The Journal of Korean Academy of Prosthodontics
• /
• v.54 no.2
• /
• pp.110-119
• /
• 2016

Purpose: This study is aimed to assess changes of stress distribution dependent on different connection lengths and placement of the fixture top relative to the ridge crest. Materials and methods: The internal-conical connection implant which has a hexagonal anti-rotation index was used for FEM analysis on stress distribution in accordance with connection length of fixture-abutment. Different connection lengths of 2.5 mm, 3.5 mm, and 4.5 mm were designed respectively with the top of the fixture flush with residual ridge crest level, or 2 mm above. Therefore, a total of 6 models were made for the FEM analysis. The load was 170 N and 30-degree tilted. Results: In all cases, the maximum von Mises stress was located adjacent to the top portion of the fixture and ridge crest in the bone. The longer the connection length was, the lower the maximum von Mises stress was in the fixture, abutment, screw and bone. The reduction rate of the maximum von Mises stress depending on increased connection length was greater in the case of the fixture top at 2 mm above the ridge crest versus flush with the ridge crest. Conclusion: It was found that the longer the connection length, the lower the maximum von Mises stress appears. Furthermore, it will help prevent mechanical or biological complications of implants.