• 한국전기전자재료학회논문지
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• 제32권6호
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• pp.490-495
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• 2019

This study performs the thermal aging of chlorosulfonated polyethylene (CSPE) for 807.36 and 1,614.48 hours at $110^{\circ}C$, which is equivalent to 40 and 80 years of aging at $50^{\circ}C$ in nuclear power plants, respectively. Flat-type CSPEs were soaked in seawater for five days and then dried for five days at room temperature. Furthermore, the soaked CSPEs were cleaned for 5 days with fresh water and dried for 1,100 days at room temperature. Through this process, the log IV of the CSPEs decreases, whereas the dissipation factor of the CSPEs increases as thermally accelerated aged years increase at the measured frequency. Although the phase degree of the response voltage versus excitation voltage of the CSPEs increases, that of the response current versus excitation voltage decreases with the thermally accelerated aging. The thermal conductivity of the CSPEs increases slightly, but the thermal diffusivity does not vary with the thermally accelerated aged year increase. The displacement of the compressive strength of the CSPEs decreases gradually as the thermally accelerated aged years increase.

• 전기학회논문지
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• 제65권5호
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• pp.819-824
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• 2016

The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 33.64 and 67.27 days at 110[$^{\circ}C$], equivalent to 40 and 80 years of aging at 50[$^{\circ}C$], respectively. These samples were referred to as CSPE-0y, CSPE-40y and CSPE-80y, respectively. As the accelerated thermally aged years of the CSPE increase, the insulation resistance[$\Omega$] at 20[Hz], 500[Hz], and 2[KHz], and the percent elongation [%EL] of the CSPE decrease. However, the dissipation factor($tan{\delta}$) at 20[Hz], 500[Hz], and 2[KHz], the apparent density[$g/cm^3$], the glass transition temperature and the melting temperature of the CSPE were increased. The period of time that the voltage has to be applied until electric breakdown of the CSPE-0y is longer than that of the CSPE-40y, and the CSPE-80y, but the dielectric strength of the CSPE-80y is lower than that of the CSPE-0y and the CSPE-40y. The differential temperatures after the AC and DC voltages are applied to CSPE-0y, CSPE-40y and CSPE-80y are 0.026~0.028[$^{\circ}C$], 0.030~0.042[$^{\circ}C$], 0.018~0.045[$^{\circ}C$], respectively. The variations of temperature for the AC voltage are higher than those for the DC voltage when an AC voltage is applied to CSPE-0y, CSPE-40y and CSPE-80y. It is found that the dielectric loss owing to the dissipation factor[$tan{\delta}$] is related to the electric dipole conduction current. It is ascertained that the ionic (electron or hole) leakage current is increased by the separation of the branch chain of CSPE polymer from the main chain of the polyethylene as a result of thermal stress due to accelerated thermal aging as well as by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$ after seawater soaking.

• 대한통합의학회지
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• 제10권4호
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• pp.121-136
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• 2022

Purpose : Marine therapy is an activity that promotes public health such as constitution improvement, immunity improvement, and anti-aging by utilizing marine therapeutic resources such as seawater, mud, seaweed, salt and sea climate. In Europe developed countries, the marine therapy industry has been developing for centuries, with France, Germany, and Israel leading the way. Currently, it has achieved great industrial achievements and is of great help in improving the human health. The purpose of this study is to investigate how marine therapeutic resources benefit to human health, as well as how to study and utilize their efficacy. We analyzed previous research articles related to the effects of marine therapeutic resources. Methods : The study included a total of 830 published literatures in the last 20 years from the Republic of Korea and other contries. PubMed and Google Scholar were utilized to collect the foreign source while the local scientific publications were accessed through the Korean Education and research Information Service (KERIS) and Korean studies Information Service System (KISS). The keywords used to search foreign literature were "marine therapy", "Thalassotherapy", "seawater", "deep seawater", "saline groundwater", "sand therapy", "mud therapy", "hydrotherapy", "seaweed", "Sun light", "sea salt", "marine animal", and "marine microorganisms" were combined, and for the domestic literature, the keywords were "marine therapy", "marine therapeutic resources", "seawater", and "sand". Results : A total of 830 research papers were found as a result of searching for domestic and international papers related to marine therapeutic resources. The collected documents were classified into 175 seawater resources, 259 marine mineral resources, 41 marine environment, and 355 marine organisms. The efficacy of each marine therapeutic resources was analyzed. By resources type, there were about 213 papers on the efficacy of seaweed, followed by about 175 papers on seawater, 142 on microorganisms, 124 on mud/peat, and sand, salt, minerals and others are appeared in order (Table 1). Conclusion : Korea has the highest marine biodiversity index, excellent tidal flats, four distinct seasons, and various sea environments of the East sea, Yellow sea, South sea and Jeju sea. For this reason, Korea has a much more diverse marine therapeutic resources than other advanced countries in the marine therapy industry. prebiously, we thought that the sea was only valuable as a shipping port and fishery industry. But now, it been shown that the ocean can become a new industrial field which can contribute to human health and well-being by providing healing and therapy to people through the gift of marine resources.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.539-552
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• 2013

To establish an aging management plan considering seawater influx and changes in groundwater within nuclear power plant sites, the characteristics of groundwater flow must be understood. This study investigated the characteristics of groundwater flow within the site and analyzed groundwater level recorded by monitoring wells to evaluate groundwater flow characteristics and elements that affected these characteristics for supplying the information to conduct the appropriate aging management for ensuring the safety of the safety-related structures in Shin Kori Unit 1 and 2. The increase in groundwater level during the wet season results from high sea-level conditions and the large amount of precipitation. As a result of the analysis of groundwater distribution and change characteristics, the site could be divided into a rainfall-affected area and a tide-affected area. First, the rainfall-affected area can further be divided into areas that are affected simultaneously by excavation, backfill, and a permanent dewatering system. Secondly, areas that are not affected by excavation, or the dewatering system, or by structure arrangement and excavation. Analysis of the spectrum for wells affected by tides resulted in confirmation of the M2 component (12.421 hr) and S2 component (12.000 hr) of the semidiurnal tides, and the O1 component (25.819 hr) of the diurnal tides. In the cross-correlation results regarding tides and groundwater levels, the lag time occurred diversely within 1-3 hours by the effect of the well location from sea, the distribution of the backfill material with depth, and the concrete structure.

• 한국구조물진단유지관리공학회 논문집
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• 제16권4호
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• pp.25-33
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• 2012

해상송전철탑 구조물에 있어서 구조 및 재료 손상에 대해 주기적으로 안전점검을 실시하고, 그 결과를 이용한 수명관리(life management)의 시행은 적극 추천되는 일이다. 본 연구에서는 영흥도 시화호 내에 있는 총 6개의 해상송전철탑에 대해서 강재부재에 대해 3가지, 콘크리트 기초에 대해 5가지, 해수 중 강관파일 및 해수 자체에 대해 4가지 형태의 열화점검을 각각 수행하였다. 강재에 대한 점검 항목들은 외관조사, 부재두께, 도막상태 등에 대한 것이고, 콘크리트 기초에 있어서는 균열형상, 압축강도, 중성화깊이, 염화물 함유량 등에 대한 항목, 그리고 해중 강관파일에 있어서의 전위 및 양극조사에 따른 부식정도, 동영상 촬영 및 해수의 수질환경성 평가 등에 대한 항목이다. 이와 같은 정기적 열화점검은 연속 3년 동안 매년 10월경에 동일위치에 대해 평가하였다. 결과적으로 본 연구에서는 이러한 자료를 체계적으로 활용함으로써 해상송전철탑 안전성 유지관리에 유익하게 적용될 수 있는 새로운 열화지표를 개발하였다.

• Composites Research
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• 제23권1호
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• pp.44-50
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• 2010

본 연구에서는 염수 침수 실험과 염수 분무 실험이라는 두 가지의 실험을 위그선의 구조재료로 사용될 3가지 다른 복합재료 시스템에 대해서 해수와의 접촉에 의한 물성저하를재현하기 위해 수행하였다. 140일간 염수환경하에서 노화시킨 후 탄소섬유 복합재료와유리섬유 복합재료의 인장, 압축, 전단 강성과 강도 및 층간 전단 강도를 측정하였다. 기본 물성파의 비교를 통해서 염수환경이 복합재료의 기계적 물성에 미치는 영향이 평가되었다. 실험을 통해 염수 분무환경과 침수 환경의 차이는 거의 영향을 미치지 않음을 확인하였다. 탄소섬유 복합재료의 경우 인장 물성에 적은 손실이 발생한 반면 유리섬유 복합재료에서는 인장물성의 저하률이 탄소섬유 복합재료에 비해서 큼을 확인하였다. 그리고 모재 지배적 물성들의 큰 물성저하가 관찰되었다. 이를 통해, 염수는 복합재료의 섬유와 모재 사이의 계면을 퇴화시키고, 또한 모재 자체 물성과 유리섬유의 물성을 저하시킬 수 있음을 확인하였다.

• Corrosion Science and Technology
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• 제5권1호
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• pp.33-38
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• 2006

Current coating practice requires the thickness of anti-corrosion organic coatings to be over $250{\mu}m$ for immersion parts of ships and offshore structures and the corrosion resistance of these coatings has been evaluated by destructive and qualitative analysis. Recently, Electrochemical Impedance Spectroscopy(EIS) method has been employed, as an alternative, to evaluate corrosion resistance of organic coatings. This method is characterized as being nondestructive, reproducible, and quantitative in evaluating aging of organic coatings. In this study, EIS method was adopted to quantitatively and effectively select the coating systems having optimized protective performance. Evaluations of several epoxy and epoxy/polyurethane coating systems typically used for ships and offshore structures were carried out in wet($50^{\circ}C$, $90^{\circ}C$) and dry(room temp.) environments to accelerate the degradation of the organic coatings. These results were compared with the conventional scribed(scratched) test results. The plausible prediction model for determining the remaining life-time of coating systems was also proposed based on variations of impedance data, FT-IR and $T_g$ measurements results.

• 수산경영론집
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• 제44권2호
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• pp.19-33
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• 2013

China is the world's largest producer of aquatic products and its fishery sector is comprised primarily of aquaculture facilities, both fresh and seawater, and a much smaller wild catch component. The expansion of the aquaculture sector continues to boost China's aquatic output. The increase is attributable to several factors. Among them rapidly growing domestic demand is no doubt one of the most important reasons. Rapid economic growth and rising disposable income are influencing domestic consumption and the economic recovery of major import markets is further stimulating consumption of China's aquatic products. This paper tries to examine the status, trend and reasons of consumption of aquatic products in China. Based on the analysis on the consumption of aquatic products and its change, this paper utilizes panel regression model to estimate the affecting factors of aquatic products consumption in China. By using panel data between 1997 and 2010, the results indicate that income, urbanization, aging and dummy variable have positive effects and fish price index has negative effect on China's aquatic products consumption as predicted. However, effects of meat consumption and education on fishery consumption are totally opposite with our predictions. In other words, it turns out that meat consumption has positive effect on fish consumption while education turns out to have negative effect. Finally the member of household does not show any significant effect on consumption of aquatic products in China.

• 한국구조물진단유지관리공학회 논문집
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• 제23권3호
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• pp.136-142
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• 2019

원자력발전소 콘크리트 구조물은 해안가에 접해 있으며, 해수를 취수하여 냉각수로 사용하기 때문에 염해에 의한 내구성은 매우 중요하다. 이를 위해 3년간의 염해 장기침지시험을 실시하여 염화물이온확산계수의 변화 및 재령계수(m)을 평가한 결과 4,000 Class인 구조물 기초의 m은 0.35~0.39로 KCI나 ACI 제안값과 유사한 결과를 나타내었고 5,000 Class인 필수 냉각수 구조물 및 터널은 0.44~0.53, 6,000 Class인 원자로 격납건물은 0.62로 FIB 제안값과 유사하였다. 실측된 재령계수로 내구수명을 예측한 결과 원전의 모든 안전관련 콘크리트 구조물은 설계수명 60년 이상을 만족하는 것으로 나타났다.

• 한국수산과학회지
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• 제55권5호
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• pp.662-669
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• 2022

The purpose of this study is to test the effects of electrolyzed water treatment on dried-laver Pyropia sp. processing facilities to control microbial contamination. Following the progression of the process to the next step, as well as during the lapse between process operating hours, the contamination level of total viable cell counts (TVC) and total coliform (TC) of laver increased. The TVC increased during the aging step, and after the molding-drying steps were completed, it increased by approximately 2.0 log CFU (colony forming unit)/g. Freshwater used for processing in April had a TVC of 4.31 log CFU/mL, which was more polluted than 2.61 log CFU/mL of seawater. Electrolyzed water was used to treat the sponge used in the laver-molding process, which resulted in a 2 log CFU/mL decrease.The TVC of dried-laver decreased by 1 to 2 log CFU/g when electrolyzed water was applied to the process. In conclusion, application of electrolyzed water in dried-laver processing was shown to be effective in reducing the microbiological contamination of the final product.