• Steel and Composite Structures
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• 제38권1호
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.46-51
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• 2011

High-rise buildings are widely being constructed in the Middle-East, South-East, and East Asia. These buildings are usually willing to stand for the landmark of the region and, therefore, exhibit some extraordinary features such as super-tall height, elevation set-backs, overhangs, or free-form exterior surface, all of which makes the construction difficult, complex, and even unsafe at some construction stages. In addition to the elaborately planned construction sequence, prediction and monitoring of building's movement during construction and after completion are required for precise and safe construction. This is often called the Building Movement Control during construction. This study describes Building Movement Control of the KLCC Tower, a 58-story office building currently being built right next to the famous PETRONAS Twin Towers. The main items of the Building Movement Control for the KLCC Tower are axial shortening and verticality. Preliminary prediction of these items are already carried out by the structural design team but more accurate prediction based on construction stage analysis and combined with time-dependent material testing, field monitoring, and site survey is done by the main contractor. As of September 2010, the Tower is under construction at level 30, where the plan abruptly changes from rectangle to triangle. Findings and troubleshooting until the current construction stage are explained in detail and implementations are suggested for future applications.

• 한국자기학회지
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• 제11권2호
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• pp.58-62
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• 2001

L $i_{0.5}$ F $e_{2.5-x}$A $l_{x}$ $O_4$ 페라이트계에 대한 XRD와 Mossbauer 스펙트럼을 측정 분석하였다. $Al^{3+}$ 씨온의 치환량 x가 증가할수록 격자상수는 작아지고, 값이 0, 0.3, 0.6인 시료에서는 두 site의 F $e^{3+}$ 이온에 의한 두 개의 6선 흡수선이 나타났고, x가 0.9, 1.2인 시료에서는 6선 흡수선외에 열에 의한 전자적 완화현상에 기인한 2선 흡수선이 공존하였으며, x가 1.5인 시료는 2선 흡수선만 나타났다. 공명흡수면적으로 계산된 L $i_{0.5}$ F $e_{2.5-x}$A $l_{x}$ $O_4$ 페라이트계의 금속 양이온 분포식은(L $i_{1-a}$$^{+}$F $e_{a}$ $^{3+}$ ) z으로 나타낼 수 있었고, 시료내의 $Al^{3+}$ 의 증가는 B-site의 F $e^{3+}$ - $O^{2-}$ 결합거리를 증가시켜 공유 결합성을 약화시키는 것으로 확인되었으며, $Al^{3+}$ 씨 증가에 따라 B-site의 F $e^{3+}$ 이온의 수가 감소하여 A-B 초 교환 상호 작용이 약화되는 것을 알 수 있었다.다.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5906-5914
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• 2013

최근 국내에서 철도부지 상부에 인공지반을 구축하고, 인공지반 위에 복합주거타운을 건설하는 정책이 추진되고 있다. 이에 상부 구조물 및 인공지반을 지지할 수 있는 적합한 기초형식이 요구되는데, 철로와 철로 사이의 좁은 공간에 급속 시공 가능한 기초 형식 중 가장 대표적인 방법은 마이크로파일로 알려져 있다. 그러나 주기초로 마이크로파일이 사용될 경우 기초 시공비가 크게 증가하게 된다. 따라서 본 연구에서는 마이크로파일의 경제성 및 지지력을 향상시키면서 철도상부 인공지반에 적합한 신개념 마이크로파일을 제안하였다. 신개념 마이크로파일은 지반을 Jet Grouting 공법을 이용하여 지반의 일정 영역을 고결시킨 뒤 강봉을 시공하는 방법에 Jet Grouting 시 말뚝체를 파형(waveform)의 형상으로 시공하여 지지력을 향상시키고 기존 마이크로파일 대비 말뚝의 전체 길이를 줄여 경제성을 높이고자 한 방법이다. 본 연구에서는 2차원 축대칭 유한요소해석을 수행하여 이러한 파형 마이크로 파일의 지지거동을 분석하였다. 해석 결과 파형 마이크로파일은 일반 마이크로파일에 비해 길이가 15% 정도 감소하였음에도 불구하고 동일한 설계하중에서 변위가 감소하여 지지력 및 경제성 측면에서 효과가 있는 것으로 나타났다. 또한, 파형 마이크로파일의 요철에 의한 주면 마찰력 증가효과는 상대적으로 연약한 토층에서 큰 것으로 나타났다.

• 한국지반공학회논문집
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• 제34권8호
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• pp.37-49
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• 2018

지진에 의해 액상화 현상이 발생하면 지반의 침하 혹은 측방유동으로 지중 및 상부 구조물의 손상을 유발하기 때문에 이를 사전에 예측 대비하는 것이 매우 중요하다. 2017년 11월 15일에 발생한 $M_L=5.4$의 포항지진은 국내지진 관측이래 액상화 피해사례가 처음으로 접수되었으며 연구자들이 이에 대한 분석을 수행 중이다. 2018년 춘계 한국지진공학회에서 발표된 포항지역의 액상화 위험지도의 경우 지반조사 결과만을 활용하여 LPI(Liquefaction Potential Index)를 계산하고 대상지역의 피해를 추정하였다. 이때 보고된 결과에 따르면 포항지역이 전반적으로 액상화에 취약하며 상대적으로 위험해 보이는 지역은 실제 피해가 발생했던 지역과 유사하였다. 하지만 액상화 위험도는 실제 발생한 피해보다 과대 예측하였기에 액상화 피해수준 범위에 문제점이 제기되었다. 따라서 본 연구에서는 액상화 현상이 관측된 구간에서 1차원 지반응답해석을 수행하여 액상화 발생가능성을 분석하였다. 그 결과 지반분류에 따른 평가로부터 얻어진 LPI는 액상화 위험지도를 작성 시에 과대예측 할 수 있는 것으로 나타났다.

• 콘크리트학회논문집
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• 제23권6호
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• pp.773-780
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• 2011

이 연구는 초대형 매스 구조물인 지하식 LNG 저장탱크의 바닥슬래브 및 측벽에 타설되는 매스 콘크리트의 재료특성, 배합조건, 양생조건 및 콘크리트의 타설시기와 초기온도, 외기온 등을 고려한 온도응력 해석 결과를 기술하였다. 해석 결과를 토대로 유해한 균열의 발생 가능성을 예측하고, 이를 방지하기 위한 방안을 제시하였다. 이 연구에서는 콘크리트의 단열온도 상승시험을 통하여 수화열 관리에 유리하다고 평가된 2종류(벨라이트 시멘트+석회석 미분말)의 최적배합조건을 선정하였다. 온도응력 해석의 결과에 따르면, 바닥슬래브 2단을 제외한 대부분의 분할타설 블록에서 관통균열지수가 1.2이상을 만족하였다. 바닥슬래브 2단의 경우 균열방지 대책으로 선행냉각 방안을 제시하였으며, 콘크리트의 초기온도를 $25^{\circ}C$ 범위에서 관리할 경우에는 대부분의 타설블록에서 관통균열지수 1.2이상을 만족하는 것으로 나타났다. 또한, 바닥슬래브의 경우, 표면균열지수가 1.2이상이기 때문에 양생조건을 준수하면 표면균열을 제어할 수 있으며, 측벽의 경우에도 표면균열지수가 1.0이상을 만족하기 때문에 균열의 수 및 폭을 제어할 수 있는 것으로 나타났다.

• 콘크리트학회논문집
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• 제12권2호
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• pp.99-107
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• 2000

This research investigates experimentally an effect on the properties of the high flowing concrete to be poured in the under-ground slurry wall of Inchon LNG receiving terminal(#213,214-TK) according to variations of concrete materials. Variables for sensitivity test were selected items as followings. 1) Concrete temperature (3cases), 2) Unit water (5cases), 3) Fineness modulus of fine aggregate (5cases), 4) Particle size of lime stone powder (3cases), 5) Replacement ratio of blast-furnace slag (4cases) and 6) Addition ratio of high range water reducing agent (5cases). And fresh conditions of the super flowing concrete should be satisfied with required range including slump flow(65$\pm$5cm), 50cm reaching time of flow(4~10sec), V-lot flowing time(10~ 20sec), U-box height(min. 300mm) and air content(4$\pm$1%). As results for sensitivity test, considered flow-ability, self-compaction and segregation resistance of the high flowing concrete, material variations and conditions of fresh concrete should be satisfied with the range as follwings. 1) Concrete temperature are 10~2$0^{\circ}C$(below 3$0^{\circ}C$), 2) Surface moisture of fine aggregate is within $\pm$ 0.6%, 3) Fineness modulus of fine aggregate is 2.6$\pm$0.2, 4)Replacement ratio of blast-furnace slag is 45~50% and 5) Addition ratio of high range water reducing agent is within 1%. Based on the specification for quality control, we successfully finished concrete pouring on the under-ground slurry wall having 75,000㎥(#213,214-TK) and accumulated real date in site.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2008-2014
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• 2011

Serotonin or 5-hydroxytryptamine subtype 2C ($5-HT_{2C}$) receptor belongs to class A amine subfamily of G-protein-coupled receptor (GPCR) super family and its ligands has therapeutic promise as anti-depressant and -obesity agents. So far, bovine rhodopsin from class A opsin subfamily was the mostly used X-ray crystal template to model this receptor. Here, we explained homology model using beta 2 adrenergic receptor (${\beta}$2AR), the model was energetically minimized and validated by flexible ligand docking with known agonists and antagonists. In the active site Asp134, Ser138 of transmembrane 3 (TM3), Arg195 of extracellular loop 2 (ECL2) and Tyr358 of TM7 were found as important residues to interact with agonists. In addition to these, V208 of ECL2 and N351 of TM7 was found to interact with antagonists. Several conserved residues including Trp324, Phe327 and Phe328 were also found to contribute hydrophobic interaction. The predicted ligand binding mode is in good agreement with published mutagenesis and homology model data. This new template derived homology model can be useful for further virtual screening based lead identification.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2008년 추계학술발표대회 논문집
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• pp.131-134
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• 2008

The numbers of the elderly who suffer Empty Nest Syndrome have been accelerated as an aging population has increased vastly and nuclear families have been a dominating family type in modern Korean society. To make the elderly get out of this phenomenon and live actively, the scheme of converting their existing houses into shared houses was set as a hypothetical solution in this study, and finding out the responses of the elderly who owns their own houses is the purpose of the study. A small workshop panel method was used and the elderly aged 55 years upwards took part and they own a detached house that is relatively large for the elderly or the elderly couple to live alone. The workshop was consisted of 3 stages: 1. a survey 2. an interview 3. a site visit. Through this, problems that the elderly have been experiencing within their houses were looked into and the responses of the elderly on converting their houses to shared houses by introducing developed schematic plans. As a result, positive responses from the house owners were carried out based on the fact that subsidies from the government on house renovation and tenants matching programs are supported. Shared houses could provide home owners economical support with rents and help them to feel less lonely. This is one way of supporting the elderly to live and age actively in their later lives. Therefore, this idea should be established in connection with preparing aging, aged, and super-aged society.

• BMB Reports
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• 제42권6호
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• pp.373-379
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• 2009

5-Hydroxyuridine (5-OHU) is a major lesion of uridine and cytosine produced in RNA by various chemical oxidants. To elucidate its biochemical and biophysical effects on RNA replication, the site-specifically modified oligoribonucleotides containing 5-OHU were synthesized with C5-hydroxy-5'-ODMTr-2'-TBDMS-uridine phosphoramidite using automated solid phase synthesis. The base-pairing properties of nucleotides opposite 5-OHU in 24 mer oligoribonulcleotides with dNTP were studied using three reverse transcriptases (Super-$Script^{TM}II$-, AMV-, MMLV-RT) in cDNA synthesis. Adenine as well as guanine was incorporated preferentially by all reverse transcriptases. In the UV-melting temperature experiment, the results from the relative stabilities of the base pairs were A : 5-OHU > G : 5-OHU > T : 5-OHU $\approx$ C : 5-OHU. Circular Dichroism (CD) studies showed that DNA-RNA containing 5- OHU heteroduplexes exhibit a similar conformation between the A-type RNA and B-type DNA. These results suggest that 5- OHU from oxidative damage was mainly influenced by adenine mismatch.