• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.31-40
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• 2014

LNG storage outer tank is a vertically and horizontally prestressed concrete wall structure. Therefore, when the storage tanks become larger, prestressing tendons become longer and eventually the prestressing loss becomes larger. Also, recently, bomb terrors and accidental crashes have occurred frequently on important infrastructures. Therefore, LNG storage tanks are also exposed to these dangerous scenarios, where they need to be evaluated and protected from these threats. Therefore, in this study, the behavior of 270,000 kL LNG storage outer tank impacted by a flying object is evaluated using implicit FEM code, LS-DYNA. In the analysis, the prestress loss due to the increased length of prestressing tendons from enlargement of outer tank is considered. A comparison study between the LNG tanks with and without prestress loss is performed to investigate the impact behavior and the effect of prestressing force change on the safety and serviceability prestressed concrete containment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.927-935
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• 2013

Recently, bridge structures has progressed the researches about seismic performance by occurrence of earthquake increased compared with the past. In the substructure of bridge, confining transverse reinforcement has arranged in plastic hinge region to resist the lateral load which increased the lateral confining effect. Columns are increased the seismic performance through secure of the stiffness and ductility The design specification for arrangement of confining transverse reinforcement same specification of domestic and international that suggested to solid reinforced concrete column(RC). This design specification have limits for Internally Confined Hollow RC(ICH RC) column because of different the component and performance characteristics of column. In this paper suggested the modified equation for economics and rational design through investigation of displacement ductility when applied the existing specification at the steel composite hollow RC column.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.520-526
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• 2019

I-type girders are widely applied as very economical sections in plate girder bridges. There has been research on developing composite laminated panels, curved plates reinforced with closed-end ribs, and new forms of ribs and compression flanges for steel box girders. However, there is a limitation in analyzing the exact cause of local buckling caused by an I-type girder's webs. Therefore, an I-type girder's web was modeled using the finite element analysis program LUSAS 17.0 before and after reinforcement. We checked for the minimum thickness criteria presented in the Korea highway bridge design code, and the cause of buckling after performing a linear elastic buckling analysis of dead and live loads was analyzed. Before reinforcement, an eigenvalue (λ₁) at the 1st mode was 0.7025, the critical buckling load was smaller than the applied load, and there is a buckling. After reinforcement, when applying vertical and horizontal stiffeners to the web part of the girder at support, a Nodal line was formed, the eigenvalue was 1.5272, and buckling stability was secured. To improve buckling trace of the girder at the support, an additional plate was applied to the web at the support to ensure visual and structural safety, but buckling occurs at center of web. The eigenvalue (λ₁) was 3.5299, and this method is efficient for reinforcing the web of the support.

• Atmosphere
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• v.15 no.2
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• pp.75-90
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• 2005

This study examines the impacts of land cover changes on the East Asia summer monsoon with the National Center for Atmospheric Research Regional Climate Model (NCAR RegCM2), coupled with Biosphere Atmosphere Transfer Scheme (BATS). To assess the goals, two types of land cover maps were used in the simulation of summer climate. One type was NCAR land cover map (CTL) and the other was current land cover map derived from satellite data (land cover: LCV). Warm and cold surface temperature biases of $1-3^{\circ}C$ occurred over central China and Mongolia in CTL. The model produced excessive precipitation over northern land area but less over southern ocean of the model domain. Changes of biophysical parameters, such as albedo, minimum stomatal resistance and roughness length, due to the land cover changes resulted in the alteration of land-atmosphere interactions. Latent heat flux and wind speed in LCV increased noticeably over central China where deciduous broad leaf trees have been replaced by mixed farm and irrigated crop. As a result, the systematic warm biases over central China were greatly reduced in LCV. Strong cooling of central China decreased pressure gradient between East Asian continent and Pacific Ocean. The decreased pressure gradient suppressed the northward transport of moisture from south China and South China Sea. These changes reduced not only the excessive precipitation over north China and Mongolia but also less precipitation over south China. However, the land cover changes increased the precipitation over the Korean Peninsula and the Japan Islands, especially in July and August.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.405-413
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• 2015

In the US, the number of cases of subterranean water contamination from tritium leaking through a damaged buried nuclear power plant pipe continues to increase, and the degradation of the buried metal piping is emerging as a major issue. A pipe blocked from corrosion and/or degradation can lead to loss of cooling capacity in safety-related piping resulting in critical issues related to the safety and integrity of nuclear power plant operation. The ASME Boiler and Pressure Vessel Codes Committee (BPVC) has recently approved Code Case N-755 that describes the requirements for the use of polyethylene (PE) pipe for the construction of Section III, Division 1 Class 3 buried piping systems for service water applications in nuclear power plants. This paper contains tensile and slow crack growth (SCG) test results for high-density polyethylene (HDPE) pipe welds under the environmental conditions of a nuclear power plant. Based on these tests, the fracture surface of the PENT specimen was analyzed, and the fracture mechanisms of each fracture area were determined. Finally, by using 3D finite element analysis, limit loads of HDPE related to premature failure were verified.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.519-530
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• 2013

Cyclic tests on modular building units for low-rise buildings composed of stud panels and a light-weight steel perimeter frame, were performed to evaluate the earthquake resistance such as stiffness, load-carrying capacity, ductility, and energy dissipation per load cycle. The strap-braced and sheeted stud panels were used as the primary lateral load-resistant element of the modular building units. Test results showed that the modular building units using the strap-braced and sheeted stud panels exhibited excellent post-yield ductile behaviors. The maximum drift ratios were greater than 5.37% and the displacement ductility ratios were greater than 5.76. However, the energy dissipation per load cycle was poor due to severe pinching during cyclic loading. Nominal strength, stiffness, and yield displacement of the modular building units were predicted based on plastic mechanisms. The predictions reasonably and conservatively correlated with the test results. However, the elastic stiffness of the strap-braced stud panel was significantly overestimated. For conservative design, the elastic stiffness of the strap-braced stud panel needs be decreased to 50% of the nominal value.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.383-392
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• 2015

In subsea tunnelling, prediction of the fractured zone (or water bearing zone) ahead of tunnel face saturated by seawater with high water pressure has been a key factor for safe construction. This study verified the feasibility of utilizing induced polarization (IP) survey at tunnel face for predicting the ground condition ahead of the subsea tunnel face. A pore model was proposed to compute chargeability in granular material, and the relationship correlating chargeability with the variables affecting the chargeability was derived from the model. Parametric study has been performed on the variables to figure out the most influential factors affecting the chargeability. The results of the parametric study show that the size of narrow pores ($r_1$) and the salinity of pore water are the most influential factors on chargeability. Laboratory tests were conducted on various types of ground condition by changing the salinity of pore water, the thickness of the fracture zone and the existence of gouge (weathered granite) within the joints of the fractured zone to figure out the effect of the ground characteristics on the IP phenomenon. Test results show that the chargeability of the fractured zone saturated by seawater increases if the joints in the fractured zone are filled with gouge since the infilled gouge will decrease the size of narrow pores ($r_1$).

• The Korean Journal of Pesticide Science
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• v.6 no.2
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• pp.72-79
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• 2002

3D-QSAR between fungicidal activitives ($pI_{50}$) against metalaxyl-sensitive (SPC: 95CC7105) or metalaxyl-resisitant (RPC: 95CC7303) isolate of phytophthora blight fungus (Phytophthora capsici), and a set of 3-phenylisoxazole (A) and 3-phenyl-2,5-dihydroisoxazole (B) derivatives as substrates were conducted using comparative molecular field analyses (CoMFA). The antifungal activities of (A) were generally higher than those of (B). And it is assumed that the most stable conformation of the active substrate was approximately planar from conformational search. The CoMFA models proved a good predictive ability and suggested that the electronic field of substrates were higher than hydropohobic field and steric field requirements for recognition forces of the receptor site. And the factors were strongly correlated (cross-validated $q^2>0.570$ & conventional $r^2>0.968$) with the fungicidal activitives. According to the CoMFA analyses, the selectivity factors for RPC suggested that the sterically bulky groups (C14 & C15) and electron withdrawing groups (C15 & C16) have to be introduced to the ortho, meta and para-position on the benzoyl moiety of substrates.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.688-695
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• 2017

This paper deals with characteristics analysis of a permanent magnet (PM) linear generator using analytical methods for wave energy harvesting. The wave energy is carried out from the movement of a yo-yo system. A linear generator using permanent magnets to generate a magnetic force itself does not require a separate power supply and has the advantage of simple maintenance. In addition to the use of a rare earth, a permanent magnet having a high-energy density can be miniaturized and lightweight, and can obtain high energy-conversion efficiency. We derived magnetic field solutions produced by the permanent magnet and armature reaction based on 2D polar coordinates and magnetic vector potential. Induced voltage is obtained via arbitrary sinusoidal input. In addition, electrical parameters are obtained, such as back-EMF constant, resistance, and self- and mutual-winding inductances. The space harmonic method used in this paper is confirmed by comparing it with finite element method (FEM) results. These facilitate the characterization of the PM-type linear generator and provide a basis for comparative studies, design optimization, and machine dynamic modeling.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.560-569
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• 2008

Microorganism survived in the root canal after root canal cleaning and shaping procedure is a main cause of root canal treatment failure. There are several mechanisms for the bacteria to survive in the root canal after chemomechanical preparation and root canal irrigation. Bacteria organized as biofilm has been suggested as an etiology of persistent periapical lesion. Recent studies were focus on removal of Enterococcus faecalis biofilm due to the report that the persistence of this bacteria after root canal treatment may be associated with its ability to form biofilm. Several investigations demonstrated that current root canal treatment protocol including use of NaOCl, EDTA and Chlorhexidine as irrigants is quite effective in eliminating E. faecalis biofilm. However, this microorganism still can survive in inaccessible areas of root canal system and evade host immune response, suppress immune activity and produce biofilm. Up to date, there is no possible clinical method to completely get rid of bacteria from the root canal. Once the root canal treatment failure occurred, and conventional treatment incorporating current therapeutic protocol has failed, periapical surgery or extraction should be considered rather than prolong the in effected retreatment procedure.