• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1854-1862
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• 2024

This study aims to investigate the strain-dependent-deformation property of Gyeongju bentonite buffer material. A series of unconfined compressive tests were performed with cylindrical specimens prepared at varying dry densities (𝜌_d = 1.58 g/cm³ to 1.74 g/cm³) using cold isostatic pressing technique. It is found that as 𝜌_d increase, the unconfined compressive strength (q_u), failure strain, and elastic modulus (E) of Gyeongju compacted bentonite (GCB) increases. Normalized elastic modulus (E_sec/E_max) degradation curves of GCB specimens are fitted using Ramberg-Osgood model and the elastic threshold strain (𝜀_e,th) is determined through the fitted curves. The strain-dependency of E and Poisson's ratio (v) of GCB were observed. E and v were measured constant below 𝜀_e,th of 0.14 %. Then, E decreases while v increases after exceeding the strain threshold. The E_sec/E_max degradation curves of GCB in this study suggests wider linear range and higher linearity than those of sedimentary clay in previous study. On top of that, the influence of 𝜌_d is observed on E_sec/E_max degradation curves of GCB, showing a slight increase in 𝜀_e,th with increase in 𝜌_d. Furthermore, an empirical model of q_u with 𝜌_d and a correlation model between q_u and E are proposed for Gyeongju bentonite buffer materials.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.63-75
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• 2012

This paper gives some basic requirements and preferences of various geological environmental conditions for the final deep geological repository of spent nuclear fuel (SNF). This study also indicates how the requirements and preferences are to be considered prior to the selection of sites for a site investigation as well as the final disposal in Korea. The results of the study are based on the knowledge and experience from the IAEA and NEA/OECD as well as the advanced countries in SNF disposal project. This study discusses and suggests preliminary guideline of the disposal requirements including geological, mechanical, thermal, hydrogeological, chemical and transport properties of host rock with long term geological stabilities which influence the functions of a multi-barrier disposal system. To apply and determine whether requirements and preferences for a given parameter are satisfied at different stages during a site selection and suitability assessment of a final disposal site, the quantitative criteria in each area should be formulated with credibility through relevant research and development efforts for the deep geological environment during the site screening and selection processes as well as specific studies such as productions of safety cases and validation studies using a generic underground research laboratory (URL) in Korea.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.533-541
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• 2004

Atopic dermatitis, also called congenital fever, is a allergic eczema of chronic itching disease. It is a recurrent and familial disease and appears on a wide age group from infant to adult. It is very common, and the ratio of occurrence is about $9{\~}l2\%$ of a child. However. it is showing trend of continuous increase by social and natural environment, food culture, and life style, recently. The human skin plays a barrier role against a physical and chemical stimulus from external environment. According to the latest study, the decreased amount of ceramide in horny layer impairs the bier function and moisture-maintaining function of skin in atopic dematitis patient. Ceramide is a kind of the sphingolipid in which a fatty acid is connected to sphingosin. Ceramide constitutes about $40\%$ of total lipid between keratinocytes and has the function of defense wall and building regular structure to suppress moisture vaporization in horny layer. In horny layer of skin a comified cell is composed of multi-layer structure of a brick shape, and, as for this cornified cell, it is strongly connected by ceramide, cholesterol, and free fatty acid. Here, we described the effects of a cream containing ceramide on the recovery of skin harrier function of atopic dermatitis patient. The safety and efficacy of latex and liquid formula were evaluated as cosmetics for atopic dermatitis. The latex products was composed of intercellular lipid components-ceramide, cholesterol, and free fatty acid-to restore skin barrier function in atopic dermatitis patients. The liquid one contained beta-glucan, magnolia extracts, and licolice extracts, which have skin immunomodulatory and anti-inflammatory effects. It is also confirmed that their possibility on new cosmetic market of atopic dermatitis.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.56-62
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• 2013

Poly (ethylene naphthalate) (PEN), which is likely to be widely used in various application due to good barrier properties, is manufactured by condensation polymerization of 2,6-dimethylnaphthalene dicarboxylate (2,6-NDC) or 2,6-naphthalene dicarboxylic acid (2,6-NDA) with ethylene glycol. In this study, an analytical method to determine monomers in food simulants, which might migrate from PEN food contact materials into food, was developed. The HPLC-UV method was validated for 2,6-NDC and 2,6-NDA. The obtained validation parameters were selectivity, sensitivity, linearity, precision and recovery. The simultaneous HPLC method was considered the be most effective analytical method to determine 2,6-NDC and 2,6-NDA in food simulants.

• Korean Journal of Occupational Health Nursing
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• v.6 no.2
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• pp.156-167
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• 1997

In Korea, based on the Revised Law of Occupational Safety and Health a new entity of institution was set up in 1990 to provide occupational health services to SSE in which three sorts of personnel as a team have to be involved. These institutions, in charge of scores to hundreds of workplace area-wide, have been providing occupational health services without payment from employers or employees, and government reimburses through the Occupational Injury Prevention Insurance since 1993. As a service provider, a team is composed of doctors, nurses and industrial hygienists. Undergraduate and postgraduate educations for the SSE occupational health are not specified and the question on the performance of the personnel has been raised. This study was designed to analyze the facilitating factors of and barriers to the performance and its improvement of these personnel. In 1997, the survey was conducted with all 58 institutions. Structured questionnaires were mailed to 200 personnel who were providing the occupational health service for SSE. The response rate was 51.7% for doctors, 58.6% for nurses, and 60.3% for industrial hygienist, respectively. Results are as follows : 1) There is a guideline for occupational service mandated by the government. Under the guideline, the minimum frequency of visiting workplace is assured with six times of doctors, 17 times for nurse and industrial hygienist in a year. There are one doctor for every 200 factories, one nurse and one hygienist for every 100 factories. 2) All respondents have basic qualification for occupational health service. About 16.7%. of doctors are certified in industrial medicine or preventive medicine, and 64.7% of industrial hygienists had first grade certification. Totally 66.7% of personnel have been involved in occupational health for more than one year. 3) As a support system for the performance improvement, 66.3% respond that they have been provided with educational materials, advice related to industrial environment and guidance of MSDS from Korea Industrial Safety Corporation. Most respondents indicate the lack of concern of employers and employees as a main barrier to the improvement of the service. Also they are in the need of the training opportunity more focused on SSE. The Governments policy for SSE is a principal facilitating factor. Training program focused on SSE situation, manpower, technical support, etc. are areas to be improved to have a better occupational health service for SSE in Korea.

• The Journal of Industrial Distribution & Business
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• v.10 no.9
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• pp.37-43
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• 2019

Purpose - The self quality inspection which is mandatory in Republic of Korea can play an important role in promoting food safety, but the cost for self quality inspection is also a big burden especially for small businesses. In addition, excessive or duplicated inspection costs resulting from the standard gaps of various ministries and agencies ultimately effect negative social utility. Thus, this paper aims to suggest ways to improve the analysis of self quality inspection for the Ready-to-Eat Foods in terms of dried laver, in order to reduce costs caused by overinclusion. Research design, data, and methodology - The focus of interest is seaweed in Kimbab, which is to be exempted from the Vibrio parahaemolyticus test on the three grounds. First, existing literature provides little support for the necessity of performing a microbiological test. Second, laver products do not require the V.parahaemolyticus test by international standards such as the CODEX. Third, no case was found for seaweed products on the list of information on failed food items over the 2015~16 period. Results - Other types of seaweed such as exportable and seasoning seaweed are not subject to the test. Hence, exclusion of the V.pahaemolyticus test on seaweed is a valid point, bringing about large expected cost savings to many small businesses. Conclusions - Based on a complete survey of 75 food-testing agencies from March 20th to 30th, 2018, this paper finds that the proposed revision of the Kimbab test is likely to save an average of 130,000 won per business per year. Especially, in the case of the testing fee of Salmonella spp.(n,c,m,M), the cost difference by agencies was found to be up to five times. The regional gap in testing fees can be considered an unfair barrier. Accordingly, it is necessary to examine whether the testing fee is set at an appropriate level through the cost-extraction program proposed by the Ministry Food and Drug Safety. Hence, the survey results also point out that harmonization of testing fees charged by different food-testing agencies is appropriate with respect to transparency and efficiency.

• Journal of the Korean Geotechnical Society
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• v.33 no.10
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• pp.25-31
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• 2017

The buffer is one of the major components of an engineered barrier system (EBS) for the disposal of high-level radioactive waste (HLW). As the buffer is located between a disposal canister and host rock, it is indispensable to assure the disposal safety of high-level radioactive waste. It can restrain the release of radionuclide and protect the canister from the inflow of groundwater. Since high quantity of heat from a disposal canister is released to the surrounding buffer, thermal properties of the buffer are very important parameters for the analysis of the entire disposal safety. Especially, temperature criteria of the compacted bentonite buffer can affect the design of HLW repository facility. Therefore, this paper investigated thermal properties for the Kyungju compacted bentonite buffer which is the only bentonite produced in South Korea. Hot wire method and dual probe method were used to measure thermal conductivity and specific heat capacity of the compacted bentonite buffer according to the temperature variation. Thermal conductivity and specific heat capacity were decreased dramatically when temperature variation was between $22^{\circ}C{\sim}110^{\circ}C$ as degree of saturation decreased according to the temperature variation. However, there was little variation under the high temperature condition at $110^{\circ}C{\sim}150^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.382-388
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• 2014

This study selected five observational stations in the normal direction of Jinu-do(island) shoreline and observed water temperature, electrical conductivity and pressure from March, 2012 to January, 2013(about 11 months) and attempted to see the variation characteristics of ground watertable. This study wants to know : 1) External environment force factors(tide, climate, wave etc.) affecting ground watertable variation through time series and correlation analysis. 2) Spatial variations of ground watertable and electrical conductivity change by storm event. First, we found that the station at the intertidal zone was strongly affected by wave and tide level and the stations at sand dune and vegetation zone was affected by precipitation and tide level through time series data and correlation analysis. Second, during the storm event, we found that ground watertable and electrical conductivity are stabilized at the start line of sand dune and vegetation zone and transition zone between freshwater layer and seawater layer exists in the experiment area and is about 50~70 m from coastline of the south side of Jinu-do(island).

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.820-829
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• 2020

Because ships have limited support from land, it is necessary to equip them with automatic external defibrillators (AEDs) in preparation for the incidences of cardiac arrest patients and to properly place and manage AEDs. The seafarer must have the ability to use the AEDs. This is a study to identify the placement and management of AEDs in order to increase the utilization of AEDs in ships, analyze the ability of seafarers to use AEDs and their intention to use it, and suggest improvement plans. The study was conducted from September 9, 2019, to February 20, 2020, and a total of 244 ships and 244 seafarers were surveyed. The data were analyzed by the frequency, percentage, and chi-square test using SPSS WIN 23.0 program. As a result, most of the ships with one AED number were identified, and some ships with insufficient AED placement and management were also identified. A total of 142 seafarers (58.2 %) had experience in participating in AED education; 136 seafarers (55.7 %) had intention to use AEDs; and the most barrier factor was "I don't know how to use" (63.0 %). The intention to use AEDs was high among seafarers in the position of the captain, navigator, and deck department personnel, and when they had an experience in AED training and the training period was less than six months, they were active in using AEDs. In addition, efforts to raise an awareness and education of AEDs are required for occupational groups other than navigators who are not willing to use AEDs in ships, and it is necessary to review appropriate retraining cycles through an evaluation of the seafarer's ability to use AEDs.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.228-243
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• 2023

Bentonite is widely recognized and utilized as a buffer material in high-level radioactive waste repositories, mainly due to its favorable characteristics such as swelling capability and low permeability. Bentonite buffers play an important role in ensuring the safe disposal of radioactive waste by providing a low permeability barrier and effectively preventing the migration of radionuclides into the surrounding rock. However, the long-term performance of bentonite buffers still remains a subject of ongoing research, and one of the main concerns is the erosion of the buffer induced by swelling and groundwater flow. The erosion of the bentonite buffer can significantly impact repository safety by compromising the integrity of buffer and leading to the formation of colloids that may facilitate the transport of radionuclides through groundwater, consequently elevating the risk of radionuclide migration. Therefore, it is very important to numerically quantify the erosion of bentonite buffer to evaluate the long-term performance of bentonite buffer, which is crucial for the safety assessment of high-level radioactive waste disposal. In this technical note, Two-region model is introduced, a proposed model to simulate the erosion behavior of bentonite based on a dynamic bentonite diffusion model, and quantitative evaluation is conducted for the bentonite buffer erosion with this model.