• Proceedings of the KSRS Conference
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• v.2
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• pp.535-538
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• 2006

The coastline of the Choa Phraya Rivermouth in the Upper Gulf of Thailand has been changed drastically. The western side especially at Ban Laem Sing was eroded for 400 meter in 26 years or with the rate of 15 meter per year on the average. The Metropolitan Electricity Authority has granted five years research project to us to study the efficiency of the electric pole fence as a mean to reduce the wave force and increase sedimentation rate inside for mangrove replantation. If the method works efficiently, it will be used to reclaim the coastal land loss in other areas in Thailand. The project was done since 2005 after the fence was constructed completely in October 2005. The oceanographic surveys were conducted before and after the construction in northeast monsoon season to study the impact of physical oceanographic forces on the coastline change. The sedimentation rates were measured each month. It is rather low about 2 cm/month. The subsiding rate from the load of deltaic sediment and groundwater withdraw using boring data is about 30 mm/year. The cumulative sinking rate is 55.8 cm from 1978 to 1995. We have tried to design the method of mangrove plantation in this area. The remote sensing data such as LANDSAT and aerial photos from 1987 to 2002 for 15 years were used to compute the rate of coastline change at each 50 m section along the western side of the rivermouth.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.493-498
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• 2002

Friction stir welding (FSW) is a relatively new solid-state joining process which can homogenize the heterogeneous microstructure by intensely plastic deformation arising from the rotation of the welding tool. The present study applied the FSW to an A356 aluminum (AI) alloy with the as-cast heterogeneous microstructure in the T6 temper condition, and examined an effect of microstructure on mechanical properties in the weld. The base material consisted of Al matrix with a high density of strengthening precipitates, large eutectic silicon and a lot of porosities. The FSW led to fragment of the eutectic silicon, extinction of the porosities and dissolution of the strengthening precipitates in the Al alloy. The dissolution of strengthening precipitates reduced the hardness of the weld around the weld center and the transverse ultimate tensile strength of the weld. Longitudinal tensile specimen containing only the stir zone showed the roughly same strength as the base material and a much larger elongation. Moreover, Charpy impact tests indicated that the stir zone had remarkably the higher absorbed energy than the base material. The higher mechanical properties of the stir zone were attributed to a homogenization of the as-cast heterogeneous microstructure by FSW.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.408-411
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• 2002

Effect of in-situ vibration on the properties of A-grade steel SMA weldment has been investigated. Welding was performed on the steel fixed at the experimental jig under the mechanical vibration of a given frequency. The applied frequency varied from 39 to 43.5 Hz (harmonic frequency). For weldments formed under the vibration with a sub-harmonic frequency, both the columnar width of the weld metal and the prior austenite grain size of the HAZ near the fusion line clearly decreased. This indicates that the vibration increase the cooling rate after welding. Vibration effect was also found at the weld metal formed at the center region of the weldment. The weld metal showed liner microstructure both in columnar zone and in equiaxed zone with thinner grain boundary ferrite. However mechanical properties of the weld metal did not exactly follow the microstructural changes developed under the vibration. The weld metal formed under the vibration revealed higher yield and tensile strength but lower ductility and impact toughness, compared with the conventional weld metal.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.38-42
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• 2002

HAZ(Heat Affected Zone of weldm ents) properties were investigated for a high nitrogen austenitic stainless steel with a chemical composition of Fe-0.02C-0.15Si-6.00Mn-10.0Ni-23.0Cr-2.00Mo-0.48N-0.14V. Thermal cycle of HAZ was simulated by the thermal cycle simulator (Gleeble 1500). The heat treatment was applied to the Charpy test size sample without notch under various peak temperatures and/or the holding times condition. V-notch Charpy test was performed at the temperature range of 273~77 K. Metallographic examination also was carried out by using optical microscopy, scanning electron microscopy and transmission electron microscopy. The simulated specimens revealed a slight embrittlement compared with the base materials. The impact toughness of the specimens deteriorated with the decreasing test temperature. The results from Charpy V-notch test, however, showed that significant degradation of absorbed energy caused by brittle fracture was not observed for the specimen tested in the test temperature range.

• Water for future
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• v.35 no.5
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• pp.21-30
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• 2002

The inflow into a multi-purpose dam reservoir contains many suspended solids from the upper stream during the rainy season. Concentrations of SS increased to 73.3 mg/l and the TP measurement increased to 0.09 mg/l during the rainy season in 1999. It was discovered that particles less than $10\;\mu\textrm{m}$ in size composed about 50% of the total amount. Some of these particles reduce the reservoir capacity and have an impact on water. In this study, the sediment depth at Daecheong multi-purpose dam was examined. Piston coring was performed at 9 locations At Hoenam 1 out of 9 locations examined showed maximum depth, which was 90 cm and at Muneui 3 showed the minimum depth, which was 35 cm. At Hoenam, the release rate of TN was found to be $62.14~84.72\;mg/\textrm{m}^2{\cdot}day$ in 1998. However, it was found to considerably reduced to $23.20\;mg/\textrm{m}^2{\cdot}day$ in 2001. The release rate of TP was measured at $13.02~14.38\;mg/\textrm{m}^2$.day at 1998, and it was reduced to $6.93mg/\;mg/\textrm{m}^2{\cdot}day$ in 2001.

• The Journal of Fisheries Business Administration
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• v.48 no.4
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• pp.45-66
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• 2017

Although the main objective of Free Trade Agreements (FTA) is market integration among member countries, there are limited studies supporting this impact. Our study explores whether FTA has enhanced market integration between South Korea and its FTA partners, focusing on South Korea's fishery product import market. We investigate two research questions concerning FTA impacts: first, whether trade costs declined when South Korea imported fishery products from its FTA partners after the FTA; second, if the speed of the convergence of South Korea-its FTA partners'price differential of imported fishery products on trade costs result to occur more quickly after the FTA. To determine these outcomes, we utilize a Threshold Autoregressive Model covering the sample periods from January 2002 to April 2017. Our findings demonstrate the effects of FTA on market integration are different among FTA partners. FTA has enhanced the market integration between South Korea and Norway, Vietnam, and Spain, respectively, but not for others. Therefore, we find positive evidence of FTA on fishery import market integration between South Korea and Norway, Vietnam and Spain, respectively.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.2
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• pp.57-66
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• 2018

It has been estimated that approximately 15% of reproductive-age couples suffer from infertility. Male factors contribute to almost half of infertility cases, and in many patients the underlying cause of oligoasthenoteratozoospermia is unknown. Accumulating evidence suggests that oxidative stress plays a role as a contributing factor to male infertility, and reactive oxygen species have been shown to impair sperm function and motility and to damage sperm membrane and DNA. Therefore, this review explored the evidence provided by studies published from 2002 to 2017 on the impact of oral antioxidants (vitamin C, vitamin E, L-carnitine, coenzyme Q10, zinc, selenium, and pentoxifylline) on seminal fluid parameters in men with idiopathic oligoasthenoteratozoospermia. Most of the studies were randomized controlled studies that investigated the effect of single or combined antioxidants and reported improvements in at least one semen parameter. The most noteworthy effect that was found was that the use of multiple antioxidants increased sperm motility and concentration. Nonetheless, there is a lack of agreement on the dose, the duration of treatment, and whether individual or combined oral antioxidants should be used. Therefore, the current review provides evidence supporting the use of oral antioxidants in the treatment of infertile men with idiopathic oligoasthenoteratozoospermia.

• Journal of the Korean housing association
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• v.13 no.4
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• pp.81-88
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• 2002

The purpose of this study is to accumulate basic data to establish planning direction and planning factors for the environment-friendly apartment complex. For this purpose, the survey has been conducted to residents living in an apartment housing and graduate students, architects and research experts in the field. The major findings of this study are as follows; 1) The basic concept of planning factors for environment-friendly apartment complex are energy saving, resources saving, minimizing environment pollution, natural harmony, regional identity and pursuit of residents' health & amenity. 2) For the planning factors of environment-friendly apartment complex, the residents had a great regard for aspect of Low-Impact (energy saving, resources saving, minimizing environment pollution). The experts, on the other hand, had a great regard for aspect of High-contact (natural harmony, regional identity). 3) It was increase of prime cost that the residents and experts regarded as the most important problem of planning and purchasing of environment-friendly apartment. It thus appears that the promotion of environmental consciousness of residents taking in the portion of increased cost is crucial parts and also that the role of the connected aspects such as administration, construction companies and residents must be redefined in order to manage problems caused in process of the development of it.

• Journal of Information Technology Applications and Management
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• v.15 no.1
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• pp.117-137
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• 2008

Using the service innovation system model, the development of Korean online game industry is analyzed. The model proposed by Gallouj (2002) is modified in order to reflect IT service characteristics such as network externalities. Success factors and innovations patterns of Korean online game industry are examined. First, at the early stage of her growth, Korean online game industry was not supported or coordinated by any Government policies unlike DRAM, CDMA or TFT-LCD. Many parts of technical and service innovations were unintentionally initiated by online game developing ventures without predeterminde strategies. Second, the online game industry is basically a service industry so that users' needs and technical and service characteristics are intertwined to produce innovation. The innovation system of the online game industry is quite different from conventional product technological innovation systems in a sense that there are no blueprints for innovation as well as major players in the system. Third, Government's policies for promotion of IT industry such as the broadband infrastructure installation policy, the hi-tech venture promotion policy and the military exemption policy contributed greatly to development of the online game industry. However, these policy tools were not intended for online game industry but in the end gave a great impact on the service innovation system of the online game industry.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.151-160
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• 2002

The purpose of this study was to evaluate the influence of sprue joint form on castability in dental prosthetics. The researcher carried out experimental study according to the type was divided by sprue joint form. Therefore type A was made thicken than sprue diameter of type B and type C was made it conversely. The results were as follows: 1. In the order of castability, type C(87.8%) was first and then type A(87.0%) and type B(79.2%) was last. However there was no significant difference statistically. 2. If reservior was located at the correct position and in sufficient size, internal shrinkage porosity in the casting bodies were not generated in the type of all. 3. At the reservoir, internal shrinkage porosity was generated first in type A, followed by type Band type C in the order named. Although it gives no impact on casting body, porosity seems to appear the least when it's produced in the form of type C.