• Molecules and Cells
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• v.40 no.4
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• pp.299-306
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• 2017

The transcriptional activator AphB has been implicated in acid resistance and pathogenesis in the food borne pathogens Vibrio vulnificus and Vibrio cholerae. To date, the full-length AphB crystal structure of V. cholerae has been determined and characterized by a tetrameric assembly of AphB consisting of a DNA binding domain and a regulatory domain (RD). Although acidic pH and low oxygen tension might be involved in the activation of AphB, it remains unknown which ligand or stimulus activates AphB at the molecular level. In this study, we determine the crystal structure of the AphB RD from V. vulnificus under aerobic conditions without modification at the conserved cysteine residue of the RD, even in the presence of the oxidizing agent cumene hydroperoxide. A cysteine to serine amino acid residue mutant RD protein further confirmed that the cysteine residue is not involved in sensing oxidative stress in vitro. Interestingly, an unidentified small molecule was observed in the inter-subdomain cavity in the RD when the crystal was incubated with cumene hydroperoxide molecules, suggesting a new ligand-binding site. In addition, we confirmed the role of AphB in acid tolerance by observing an aphB-dependent increase in cadC transcript level when V. vulnificus was exposed to acidic pH. Our study contributes to the understanding of the AphB molecular mechanism in the process of recognizing the host environment.

• Composites Research
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• v.30 no.2
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• pp.116-125
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• 2017

The purpose of this study is to develop silicon carbide fiber showing an excellent mechanical properties under highly oxidative conditions at high temperature. Polycarbosilane(PCS) as a preceramic precursor was used for making the SiC fiber. PCS fiber was taken by melt spinning method followed by melting the PCS at $300{\sim}350^{\circ}C$ in N2 gas. The Curing of PCS fiber was carried out in air oxygen chamber, prior to high temperature pyrolysis. Degree of cure was calculated by characteristic peak's ratio of Si-H to $Si-CH_3$ in FT-IR spectra before and after curing of PCS fiber. The properties of SiC fiber was affected greatly by the degree of cure. The SiC fiber produced by controlling fiber tension during heat treatment showed good properties. The SiC fiber exposed to $1000^{\circ}C$ at air from 1 min. up to maximum 50 hrs showed around 60% reduction in tensile strength. We found that large amount of carbon content on the fiber surface after long-term exposure has resulted in lower tensile strength.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.47-54
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• 1990

In this study, the effects of gas ratio($N_2:H_2$) and treatment time on the fatigue fracture behavior, fatigue crack growth behavior and corrosion fatigue fracture behavior for the ion-nitrided SM45C steel were investigated. The results show that the fatigue limit and corrosion fatigue strength increased in porportion to $N_2$ gas and treatment time for all kinds of specimen, used in the experiment. Compare to the non-nitrided specimen, the fatigue limit and the corrosion fatigue strength increased about $24{\sim}29%$ at $10^7$ cycles in air and $32{\sim}48%$ at $10^6$ cycles in 3% NaCl aqueous solution, respectively. Similar results were derived with SM45C steel under Compression-Tension $24{\sim}29%$ at $10^6$ cycles in air and $32{\sim}48%$ either in 3% NaCl aqueous solution or in tap water, respectively. Ion-nitrided SM45C steel showed a slow fatigue crack growth rate at relatively low range of ${\Delta}K$ compared to the non-nitrided specimen. To the contrary, its rate increase at higher range of ${\Delta}K$.

• Economic and Environmental Geology
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• v.3 no.2
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• pp.55-73
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• 1970

The district investigated covers the central and southern portions of the Uiryong Quadrangle amounting to $40km^2$ in area and is bounded approximately by geographical coordinates of $128^{\circ}$ 28' $40^{{\prime}{\prime}}{\sim}128^{\circ}$ 24' 25"E in longitude and $35^{\circ}10{\prime}{\sim}35^{\circ}14^{\prime}06^{{\prime}{\prime}}N$ in latitude. The purpose of this investigation was to provide basic information in drawing up a comprehensive development plan of the copper ore deposits known to exist in the HamanKumbuk district with special emphasis given to the ascertainment of geological and paragenetic characteristics. The area consists chiefly of shale, sandy shale and chert, all belong to Kyongsang System of Cretaceous age. Intruded into these rocks are andesite, granodiorite, basic dikes, and acidic dikes. The mineralization which took place in the area, consists of mostly fissure-filling vein deposits, numbering several tens, with varying magnitudes. The fissures and shear zones created in rocks, such as chert and granodiorite, hosted the deposition of mineralizing vapors and/or hydrothermal solutions along their openings. The strike lengths of these veins vary from 50 to 600 meters in extension and 0.1 to 3 meters in width. Although the degree of fluctuation in width is great, it averages 0.3m. The stuctural patterns, which apparently affected the deposition of veins, are fissure patterns, trend NS to $N30^{\circ}W$, and steep-pitching tension fractures as well as normal fault pattern. Ore minerals associated with vein matters are primarily chalcopyrite and small amounts of scheelite, cobaltiferous arsenopyrite, and gold and silver intimately associated with sulphide minerals. Associated with these ore mineral are pyrite, pyrrhotite, magnetite, specularite and arsenopyrite. Gangue minerals noted are quartz, calcite, chlorite, tourmaline and hornblende. In terms of the compositions of associated minerals, the vein deposits in the district could be grouped under the following four categories: 1. Pyrrhoitite, Arsenopyrite, Gold and Silver Bearing Copper Vein (Type I) 2. Calcite-Scheelite-Copper Vein (Type II) 3. Magnetite-Pyrite-Copper Vein (Type III) 4. Tourmaline Copper Vein (Type IV) Of the four types, the first and the fourth are presently yielding relatively higher grades: of copper ores and concentrates. The estimated ore reserves total some 222,000 metric tons with the following breakdown in terms of metal contents: Name of Mines Au(g/t) Ag(g/t) Cu(%) Reserves(M/T) Kunbuk 15.92 78.69 6,074 60.498 Cheil Kunbuk - - 1.040 60,847 Haman - - 2.688 101,204 222,549 As rehabilitation of old workings and/or exploration of veins at depth proceed, additional estimation of ore reserves may become apparent and necessary. With regard to the problem of beneficiation and upgrading of low-grade ores in the district, it would be advisable to make decisions on location, treating capacity and mill flowsheet after sufficient amount of exploration is completed as suggested in the report.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.166-174
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• 2000

Anchovy, EngrauEis japonica scoop nets are used in the coastal of Southern and Cheju of Korea. Especially in the Cheju, the fishing gear of scoop nets consists of upper boom, lower boom, pressing stick and bag net. They are operated by fishing boats of 6 to 10 ton class and 8 persons on board. The booms are controlled by side drum, and the net and pressing stick are hauled by only human power in operating. Therefore this fishery needs to large labor and heavy human power and has much risk. Three kinds of hydraulic winding device which controls two booms was designed and manufactured to reduce heavy labor force of scoop nets, and trial in the sea was carried out to test their performances using the commercial fishing boats of 6 ton class. The proper capacity of hydraulic pump and motor were determined by model test of boom 1/5 scale. The results obtained are as follows, 1. Tension of boom which is being drawn was the strongest and 187.5kgf when the boom's end is in the depth of 4m under the water. 2. The hydraulic motor of the fittest kind of winder has the least leakage per time than the other kinds. 3. In the best type of several winder devices, when the pressure difference was fixed $130kg/^2$ for the safe fishery, the winding velocity of boom line was 2m/sec, is faster 0.48/sec than traditional fishing method and this winder can catch the anchovy of 1.6 tonnage. 4. As a result, the crew were decreased from 8 to 6 and the problem of heavy human power and risk on fishing operation were solved by using the this winder.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.431-440
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• 2013

In this study, a standard tensile welded-joint test was conducted to select a welding electrode suitable for recently developed HSA800 steel. Two welding electrodes were available at the time of this study; one was GMAW-based and the other FCAW-based. The tensile test specimens were fabricated by joining 60mm-thick HSA800 plates according to the AWS-prequalified groove welded joint details. Specimens which violate the standard root opening distance (ROD) were also included to see if poor construction tolerance could be accommodated. During fabrication, serious concerns about the welding efficiency of the GMAW-based product were raised by a certified welder. Both welding electrodes showed satisfactory and similar performance from welded joint strength perspective. But groove welded joints made by using the FCAW-based rod consistently showed more ductile and stable behavior. The AISC provisions for PJP joint strength were shown to be very conservative under direct tensile loading. Violating the AWS prequalified ROD by 100% apparently passed the strength criteria, but unusual crater-like fracture surface was observed.

• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.345-354
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• 2016

In the present study, hybrid moment connections of welding and bar reinforcement for composite beam-column connections were proposed. Concrete-filled octagonal tube and U-section were used for the column and beam, respectively. In the beam-column connection, the top flange and web of the beam U-section were connected to the column plate by welding. However, to reduce stress concentration at the weld joints, the bottom flange of the beam was not welded to the column plate. Instead, to transfer the tension force of the beam flange, reinforcing bars passing through the column plate were used. Four exterior connections with conventional welded and hybrid moment connections were tested under cyclic loading and their cyclic behaviors were investigated. The test results showed that the hybrid moment connections successfully transferred the beam moment to the column. The strength and ductility of the hybrid moment connections were comparable to the conventional welded moment connection with exterior diaphragm; however, the connection performance was significantly affected by the details of the hybrid moment connection.

• International Commerce and Information Review
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• v.13 no.3
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• pp.403-431
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• 2011

The environmental issues including domestic measures to protect public life or health are generally easy to bring the tension between the WTO and its member countries. The standard of review, whether de novo review, total deference, or somewhere in between, is largely important in the WTO's adjudicating mechanism because it is closely related to the appropriate balance of power between sovereign nations and the WTO: The multilateral trading regime, through the proper standard of review, could harmoniously operated without interest conflicts among the member countries and at the same time between the WTO and the member countries. Irrespective the important function of the standard of review in the WTO judicial system, applicable standard of review has not been established in the current SPS Agreement. Furthermore, the nature of the SPS Agreement related in scientific factors, such as scientific experiment, data and assessment prevents the WTO's panel from applying consistent standard of review. Considering the judicial demand for the moderate treatment of the case under the SPS Agreement, this paper explores appropriate standard of review applicable the SPS-related environmental measures, particularly, by analysing the recent SPS-related dispute, US-Hormones Suspension.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.37-46
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• 2009

In this study, the seismic performance of the Buckling Restrained Knee Bracing (BRKB) system was evaluated through a pin-connected 1-bay 1-story frame. The BRKB system using a bolted channel section developed was composed of a steel plate as a load-resisting core member and two channel sections as a restrainment of the local and global buckling of the core plate. The main purpose of the BRKB system is to be used as an effective tool to re-strengthen/rehabilitate old low- and mid-rise RC frame buildings, which do not have enough seismic resistance to earthquake loadings. The main variables for the test specimens were the size of the core plates, stiffeners and the use of guide plates. The test results showed that the size of the core plate, which was the main element for the load-resisting member, was the most important parameter to achieve ductile behavior under tension as well as compression, until the maximum displacement exceed twice the design drift limit given by the AISC Seismic Provisions.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.1
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• pp.28-34
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• 2010

Purpose: The aim of this study was to evaluate short-term clinical results and second-look arthroscopic findings after double-bundle anterior cruciate ligament (DB ACL) reconstruction. Materials and Methods: Forty-nine patients, who were followed up for at least 24 months after DB ACL reconstruction, were included. Clinical results, such as, Lysholm knee and Tegner activity scores, and manual laxity and instrumented anterior laxity test results were evaluated. In fifteen patients (15 knees), second-look arthroscopy with staple removal was performed. At second-look arthroscopy, the authors assessed about reconstructed ACL rupture, subjective graft tension and extent of synovial coverage. Results: Lysholm knee scores significantly improved from 67.4 preoperatively to 96.1 at last follow-up (p<0.01). Tegner activity scale improved from 2.0 to 6.1. The Lachman test, at last follow-up, showed normal laxity in 39 (of 49) patients, and the pivot-shift test showed normal laxity in 36 (of 49) patients. Mean side-to-side differences improved significantly from 10.8 mm to 3.3 mm (p<0.01). Second-look arthroscopic findings showed that all patients had a normal or a near normal anteromedial bundle. However, 8 patients (53.3%) were found to have partial or complete posterolateral bundle rupture. Conclusion: Even though double-bundle ACL reconstruction was clinically effective means of restoring knee rotational and anteroposterior stabilities, there were some ruptured posterolateral bundles observed in cases under arthroscopy after double-bundle ACL reconstruction.