• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.19 no.3
• /
• pp.367-386
• /
• 2021

The overestimation and underestimation of the radioactivity concentration of difficult-to-measure radionuclides can occur during the implementation of the scaling factor (SF) method because of the uncertainties associated with sampling, radiochemical analysis, and application of SFs. Strict regulations ensure that the SF method as an indirect method does not underestimate the radioactivity of nuclear wastes; however, there are no clear regulatory guidelines regarding the overestimation. This has been leading to the misuse of the SF methodology by stakeholders such as waste disposal licensees and regulatory bodies. Previous studies have reported instances of overestimation in statistical implementation of the SF methodology. The analysis of the two most popular linear models of the SF methodology showed that severe overestimation may occur and radioactivity concentration data must be dealt with care. Since one major source of overestimation is the use of minimum detectable activity (MDA) values as true activity values, a comparative study of instrumental techniques that could reduce the MDAs was also conducted. Thermal ionization mass spectrometry was recommended as a suitable candidate for the trace level analysis of long-lived beta-emitters such as iodine-129. Additionally, the current status of the United States and Korea was reviewed from the perspective of overestimation.

• Resources Recycling
• /
• v.33 no.1
• /
• pp.3-14
• /
• 2024

Owing to technological advancements and energy-saving policies, the demand for LED is increasing, leading to rapid industry expansion. Consequently, efficient recycling of accumulated LED waste has become a growing social concern, and current recycling status of LED waste resources and future directions were reviewed. Currently, waste LED recycling is focused on Ga recovery. Therefore, the development of integrated recycling technologies such as pre-treatment and concentration/recovery of high valued materials is necessary. In this study, we investigated the status and recycling technologies of waste LED and presented prospects.

• Geophysics and Geophysical Exploration
• /
• v.22 no.3
• /
• pp.149-159
• /
• 2019

Borehole elemental concentration logging, measuring neutron-induced gamma rays by inelastic scattering and neutron capture interactions between neutron and formation, delivers concentrations of the most common elements found in the minerals and fluids of subsurface formation. X-ray diffraction and X-ray fluorescence analysis from core samples are traditionally used to understand formation composition and mineralogy, but it represents only part of formations. Additionally, it is difficult to obtain elemental analysis over the whole intervals because of poor core recovery zones such as fractures or sand layers mainly responsible for groundwater flow. The development of borehole technique for in situ elemental analysis plays a key role in assessing subsurface environment. Although this technology has advanced consistently starting from conventional and unconventional resources evaluation, it has been considered as exclusive techniques of some major service company. As regards domestic research and development, it has still remained an unexplored field because of some barriers such as the deficiency of detailed information on tools and calibration facility for chemistry and mineralogy database. This article reviews the basic theory of spectroscopy measurements, system configuration, calibration facility, and current status. In addition, this article introduces the domestic researches and self-development status on borehole elemental concentration tools.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.1
• /
• pp.1-7
• /
• 2013

This study was to examine growth, carbon and nitrogen responses in foliage following forest fertilization in a red pine stand. Two types of fertilizer (N:P:K=113:150:37 kg $ha^{-1}$; P:K=150:37 kg $ha^{-1}$) were applied on late April 2011. Growth, carbon and nitrogen responses of foliage were monitored 3 times (July, September, November) after fertilization. Morphological growth responses (dry mass, leaf area, specific leaf area) with foliage age were not significantly (P > 0.05) affected by fertilizer application, while needle dry mass and leaf area of July were significantly lower in current-year-old than in one-year-old or two-year-old needles of September or November. Carbon concentration and content in foliage was little affected by fertilizer application compared with sampling month or needle age, while the NPK fertilizer produced high nitrogen concentration and content of foliage. The results indicate that nitrogen concentration and content in foliage may serve as an indicator of the nitrogen status by fertilization in a red pine stand.

• Journal of Korean Society of Forest Science
• /
• v.88 no.3
• /
• pp.335-341
• /
• 1999

To investigate the effect of sulfate deposition un forest tree nutrition, 15 forest stands of Pinus thunbergii were selected throughout Yochon industrial complex, in which is influenced by chronic air pollution. Concentrations of sulfate sulfur, nitrogen, phosphorus, potassium, calcium, and magnesium were analysed fur current and 1-year-old needles of Pinus thunbergii tree. The results obtained were as follows ; 1. Significant higher accumulation of sulfate S, computed with that of unpolluted needles, was observed at all sites, ranging front 0.11% to 0.35% in current needles, and from 0.13% to 0.32% in 1-year-old needles. 2. Ranging from 0.60% to 1.42% in current needles, and from 0.58% to 0.88% 1-year-old needles, respectively, nitrogen concentrations were significantly lower at 7 sites for current needles, and at all sites for 1-year-old needles than at unpolluted site. 3. Phosphorus and potassium levels were significantly lower at very few sites, compared with unpolluted site. 4. Calcium concentrations were significantly lower at 8 sites and 9 sites for current and 1-year old needles than at unpolluted site, ranging from 0.123% to 0.352% and from 0.201% to 0.371% in 1-year old needles, respectively. 5. Ranking from 0.077% to 0.152% in current needles, and from 0.056% to 0.105% in 1-year-old needles, magnesium concentrations were lower at only 2 sites for current needles tut at 12 sites for 1-year-old needles. 6. There were significant declines of concentrations of calcium and magnesium in current needles as sulfate accumulation increased. For 1-year-old needles, there were significant negative correlations-hips between sulfate and nitrogen, potassium, calcium, and magnesium concentration. It is concluded that deposition of sulfuric air pollutant deteriorated nutrients status, resulting in tree decline, in Pinus thunbergii forest in Yochon industrial complex.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.47
• /
• pp.140-149
• /
• 2002

Sesame (Sesamum indicum L.) is probably the most ancient oilseed crop known in the world. Sesame seed is known for its high nutritional value and for having oil (51%) and protein (20%) content. The fatty acid composition of sesame oil is palmitic acid (7.8%), stearic acid (3.6%), oleic acid (45.3%), and linoleic acid (37.7%). Sesame oil is characterized by a very high oxidative stability compared with other vegetable oils. Two lignan-type compounds, sesamin and sesamolin, are the major constituents of sesame oil unsaponifiables. Sesamol (a sesamolin derivative) can be present in sesame seeds and oils in very small amount. Other lignans and sesamol are also present in sesame seeds and oils in very small amount as aglycones. Lipid oxidation activity was significantly lower in the sesamolin-fed rats, which suggests that sesamolin and its metabolites contribute to the antioxidative properties of sesame seeds and oil and support that sesame lignans reduce susceptibility to oxidative stress. Sesaminols strongly inhibit lipid peroxidation related to their ability to scavenge free radical. The sesame seed lignan act synergistically with vitamin I in rats fed a low $\alpha$-tocopherol diet and cause a marked increase in a u-tocopherol concentration in the blood and tissue of rats fed an $\alpha$-tocopherol containing diet with sesame seed or its lignan. The authors are reviewed and discussed for present status and prospects of quality evaluation and researched in sesame seeds to provide and refers the condensed informations on their quality.

• Journal of the Korea Safety Management & Science
• /
• v.25 no.1
• /
• pp.7-14
• /
• 2023

We attempted to provide an overview of the laws and current state of the 3D printing industry in South Korea and around the world, using the annual industry surveys and the Wohler report. Additionally, we reviewed articles relating to the potential exposure to hazards associated with 3D printing using metal materials. In South Korea, there were 406 3D printing-related businesses, employing 2,365 workers, and the market size was estimated at 455.9 billion won in 2021. Globally, the average growth rate of the 3D printing industry market over the past 10 years was 27.4%, and the market size was estimated at $11.8 billion in 2019. The United States had the highest cumulative installation ratio of industrial 3D printers, followed by China, Japan, Germany, and South Korea. A total of 6,168 patents related to 3D printing were registered in the US between 2010 and 2019. Harmful factors during metal 3D printing was mainly evaluated in the powder bed fusion and direct energy deposition printing types, and there is a case of material extrusion type with metal additive filaments. The number, mass, size distribution, and chemical composition of particles were mainly evaluated. Particle concentration increases during the opening of the chamber or post-processing. However, operating the 3D printer in a ventilated chamber can reduce particle concentration to the background level. In order to have a safe and healthy environment for 3D printing, it is necessary to accumulate and apply knowledge through various studies.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.11 no.1
• /
• pp.70-77
• /
• 2001

This study was conducted to identify the current status of occupational safety and health by checklist and to evaluate the airborne exposure to chemicals and to provide the appropriate recommendation for safety and health of laundries. A total of 20 laundries located in tile Gyungi district area were surveyed from July 20 to September 15, 2000. The prevalence of laundries having a stove and gas range were found to be 25 % and 55 %, respectively. Smoking is not allowed in 60 % of the laundries. Only 10 % of dry-cleaners were isolated. Ventilation systems in laundries had not been annually inspected. Most of the workers didn't put on respirators, MSDS were not available, and storage bottles did not contain warning labels. The bulk samples of dry cleaning agent include many chemicals that are not controlled by the MOL in Korea. The detected airborne organic solvents in the laundries were benzene, toluene, p-xylene, m-xylene, o-xylene, perchloroethylene, and 2-butoxy ethanol. The airborne concentrations of organic solvents were much less than the occupational exposure limits proposed by the Ministry of Labor(MOL) in Korea. But the concentrations of benzene exceeded the TLV of ACGIH. This study showed that the current status of occupational safety and health was not appropriate for workers in laundries. It is recommended that laundry workers should be educated for the treatment and storage of hazardous organic solvents to improve the occupational safety and health of the working environment as well as MSDS usage. Also, extended research and survey for the organic solvents that are not controlled by the MOL has to be conducted.

• Particle and aerosol research
• /
• v.6 no.1
• /
• pp.9-20
• /
• 2010

This study examined the concentration level of the major air pollutants in public transportation. The study was conducted between February 2009 and March 2008 at Suwon-Yeosu line in Korea. $PM_{10}$ concentration level was $100{\mu}g/m^3$ on average. The $PM_{2.5}$ to PM10 ratio in transport is 0.37, which was lower than the results published by other researches. The result also demonstrated that outdoor $PM_{10}$ concentration was about 56~60% level compared to that of the cabin. $CO_2$ concentration level in the cabin was 1,359ppm, which does not exceed 2,000ppm, which is the guideline concentration level according to the Ministry of Environment. $CO_2$ concentration level in the cabin was $CO_2=23.4{\times}N+460.2$, and about 23.4ppm in $CO_2$ concentration level increased every time one passenger was added on. The experiment conducted on the train demonstrated that the average $PM_{10}$ concentration level was $100{\mu}g/m^3$ in case of the reference cabin while average $PM_{10}$ concentration level of the modified vehicle was $68{\mu}g/m^3$. Likewise, effect of the particle reduction device for the reduction of $PM_{10}$ concentration level was approximately 21%. Meanwhile there was almost no difference in the concentration level between reference and modified cabin in case of $PM_{2.5}$. Using zeolite as an adsorbent was made to reduce the $CO_2$ concentration level in the cabin. Number of passengers was factored in, to calculate the effect of the adsorption device, which demonstrated that about 36% of $CO_2$ concentration level was reduced in the modified cabin effect of the $CO_2$ reduction device. This research analyzed the current status concerning the quality of air in the public transportation and technologies were developed that reduces major air pollutants.

• Korea Trade Review
• /
• v.47 no.6
• /
• pp.229-246
• /
• 2022

In order to understand the economic damage of economic sanctions on trade between Korea and Russia, a trade structure analysis was conducted through statistics on import and export trade between Korea and Russia. Through the structural analysis of product trade, we tried to accurately analyze the current status of product trade between Korea and Russia. In the trade structure analysis, it was confirmed that the trade in goods between Korea and Russia decreased the most in market share and trade concentration. However, trade specialization, comparative advantage by market, and intra-industry trade index were not significantly affected despite strong economic sanctions. from Russia's point of view Smart measures are needed to address the current situation to avoid a greater economic downturn. The end of the war and the restoration of partnership with other countries are considered the most beneficial solutions for Russia and all countries, but it is difficult to predict how the war will go or what economic situation Russia will be in after the war.