• Korean Journal of Construction Engineering and Management
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• v.8 no.2
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• pp.84-92
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• 2007

To reduce uncertainties and make rational plans, the presumption of contingency against a failure of projects and an occurrence of unpredictable risks is important with accurate estimations as the work progressing. Therefore, if the presumption of contingency reflecting uncertainties carries out at a decision making point of time, be able to prepare for risks. The purpose of this paper is to present a management process of contingency through the performance analysis of project. In the cost planning phase, this study offers a process which is predictable contingency and predicts the range of fluctuation of the cost, laking an advantage of EVM in construction phase. With reflecting the results from this procedure, this study presents a process, rationally manageable contingency.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1060-1068
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• 1994

Stable zirconia sol was prepared from zirconium butoxide Zr(OC4O9)4 as a precursor and ethylacetoacetate(EAcAc) or diethylene glycol(DEG) as a chelating agent under ambient agent under ambient atmosphere by Sol-Gel process. The sythesized sol was coated on 304 stainless steel substrate by dip coating, thereafter zirconia film could be obtained by heat-treatment at $600^{\circ}C$. The characteristics of coating film were determined by FT-IR, XRD, and ellipsometion peak represented Zr-O-Zr bonding of tetragonal phase was shown at 470cm-1. Crystallization of zirconia gel and film from amorphous state to tetragonal phase started at 40$0^{\circ}C$, and then transformed into monoclinic phase around $700^{\circ}C$. Zirconia film coated on 304 stainless steel substrate showed relatively low porosity of 16% when it was coated with 0.4M zirconia sol and thereafter heat-treated at 80$0^{\circ}C$ and the film was densified continuously up to 90$0^{\circ}C$. The zirconia film of 10 nm thick acted as a protective layer against oxidation up to $700^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.158-162
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• 2006

Micro gas turbine (MGT) has received attention recently as a small-scale distributed power source. Due to many advantages such as their small size, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of applications. The exhaust heat emitted by the MGT is in the form of an exhaust gas that is about $270^{\circ}C$ which is an extremely clean gas. Korea Gas Corporation (KOGAS) has researched performance characteristics of a cogeneration system combining 28kW class MGT and 13 USRT class absorption hot and chilled water generator in the local condition. The present results of this study can be summarized as follows: (1) in heating mode, the total efficiency of cogen. system is about $65\%$ and heating capacity is 33kW at 25kW MGP power (2) in cooling mode, COP is about 0.6 at 22kW MGT power.

• Corrosion Science and Technology
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• v.11 no.4
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• pp.120-128
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• 2012

The fatigue crack growth behaviors of SA508 Gr.3 Cl.2 low alloy steel in high temperature water environment were investigated. Overall, weld metal showed similar crack growth rate as that of base metal. At 0.01 Hz, fatigue crack growth rate (FCGR) was higher than that in air while the difference was smaller at 0.1 Hz. Also, FCGR showed ${\Delta}K$ dependency at 0.1 Hz only, indicating that the environmental effect was much greater at slower loading frequency of 0.01 Hz. FCGR of SA508 Gr.3 Cl.2 low alloy steel was compatible to or smaller than the ASME Sec. XI fatigue reference curves in high temperature water environment.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.504-511
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• 2003

Environmental noise at high intensities directly affects human health by causing hearing loss. Although scientific evidence currently is not conclusive, noise is suspected of causing or aggravating other diseases. Environmental noise indirectly affects human welfare by interfering with sleep, thought, and conversation. Noise emission from motorized vehicle includes power unit noise, tire/pavement noise and aerodynamic noise. Among them, tire/pavement noise is noise emission from interaction of the tire and road surface when the vehicle cruises over the surface of pavement. In general, portland cement concrete(PCC) pavement is known to create more noise than asphaltic surfaces though it has the advantage of durability and superior surface friction. However, the results of preliminary laboratory test showed exposed aggregate concrete(EAC) has and effect on reducing tire/pavement noise. Based on the laboratory test. pilot construction of exposed aggregate concrete pavement was completed and series of in-situ measurements were conducted for noise analysis including the pass-by noise measurement and the close-proximity method. Conclusively, it is expected that tire/pavement noise represent significant portion of noise levels at higher frequencies and it would be reduced on special textures of pavement such as exposed aggregate concrete.

• Journal of The Korea Institute of Healthcare Architecture
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• v.13 no.3
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• pp.25-33
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• 2007

This study is about change a necessary and natural change from institutionalized hospital based health care to a more patient centered, accessible health care. Rapidly change of social and medical facts such as growing aging population, malady, changing of medical policy are made new paradigm. This paradigm is both required to the hospital ; consolidate department and service; architectural change. Benefit to patient and hospital are many, so there are many challenges in Korean general hospital. The purpose of this study is find architectural design guideline to Korean general hospital which is struggling to change from to functional organization to the patient based care center. As a result, the type is divided into three classes, consultation type(C), some of examinations are added on consultation type(EAC), consultation and examination are fully integrated type(CEI). Each type has different organization and the proportion of area, group unit, process of treatment.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.674-677
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• 2007

Recently, construction industry has came to a crisis due to stagnation and saturation of the domestic construction market. So, many construction companies in Korea has turned their eyes upon extending the business market abroad, in order to overcome such obstacles. Even though the overseas expansion has been exploited since the mid-1960s, there still lies many problems : excessive focusing on the plant construction, a shortsighted policy of government. In this paper. we analyze the characteristics of advancement into overseas construction market and deduce the problems. then propose the new strategies based on SWOT Analysis.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1798-1806
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• 2018

When a contingency occurs in a large transmission route in a power system, it can generate various instabilities that may lead to a power system blackout. In particular, transient instability in a power system needs to be immediately addressed, and preventive measures should be in place prior to fault occurrence. Measures to achieve transient stability include system reinforcement, power generation restriction, and generator tripping. Because the interpretation of transient stability is a time domain simulation, it is difficult to determine the efficacy of proposed countermeasures using only simple simulation results. Therefore, several methods to quantify transient stability have been introduced. Among them, the single machine equivalent (SIME) method based on the equal area criterion (EAC) can quantify the degree of instability by calculating the residual acceleration energy of a generator. However, method for generator tripping effect evaluation does not have been established. In this study, we propose a method to evaluate the effect of generator tripping on transient stability that is based on the SIME method. For this purpose, the measures that reflect generator tripping in the SIME calculation are reviewed. Simulation results obtained by applying the proposed method to the IEEE 39-bus system and KEPCO system are then presented.

• Journal of Welding and Joining
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• v.5 no.3
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• pp.53-61
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• 1987

Post weld heat treatment(PWHT) is usually carried out to remove the residual stress and to improve the microstructure and mechanical properties of welded joints. By the way, welding structure transformed owing to PWHT and reheating for repair loads the random cycles fatigue as offshore welding structure of constant low cycle fatigue as pressure vessel, and then, pre-existing flaws or cracks exist in a structural component and those cracks grow under cyclic loading. Therefore, the effects of PWHT and stress ratio on fatigue crack growth behaviors were studied on the three regions such as HAZ, sub-critical HAZ and deposit metal of welded joints in SM53 steel. Fatigue crack growth behavior of as-weld depended on microstructure and fatigue crack growth rate of HAZ was the lowest at eac region, but after PWHT it was somewhat higher than that of as-wel. In case of applying the stress($10kg/mm^2$) during PWHT, fatigue crack growth resistance tended to increase in the overall range of .DELTA.K.

• Journal of Gastric Cancer
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• v.18 no.4
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• pp.328-338
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• 2018

The incidence of gastroesophageal junction adenocarcinoma (GEJAC) in Western countries has increased in recent decades, in addition to a rise in the incidence of esophageal adenocarcinoma (EAC). Gastroesophageal reflux disease (GERD), obesity, smoking, alcohol consumption, and low Helicobacter pylori (HP) infection rate have been nominated as risk factors for such cancers. Among these risk factors, the increased prevalence of GERD and obesity and the decreased prevalence of HP infection are of special interest owing to the currently increasing prevalence of GEJAC in Western countries. Although similar trends in the prevalence of GERD, obesity, and HP infection are observed in Asian countries after a time lag from Western countries, it is still uncertain if the prevalence of GEJAC in Asian countries is increasing, especially in Korea. The incidence of GERD in Korea is currently increasing; it was below 3% in the 1990s. The incidence of obesity in the Korean population is increasing owing to the adoption of westernized lifestyles, including food preferences, and the HP infection rate in Korea is known to be decreasing. Therefore, based on logical extrapolation of observations of Western countries, the incidence of GEJAC will increase in Korea. However, the proportion of GEJAC among other upper gastrointestinal malignancies in Korea appears to be currently unchanged compared with that in the 1990s. Presently, there is a lack of epidemiologic studies on this issue in this region; therefore, more studies are needed to clarify the characteristics of these tumors and to improve clinical outcomes for patients with these tumors.