• Nuclear Engineering and Technology
• /
• v.56 no.3
• /
• pp.812-818
• /
• 2024

The volume and toxicity of radioactive waste can be decreased by separating the components of high-level liquid waste according to their properties. An impregnated silica-based adsorbent was prepared in this study by combining N,N,N',N',N",N"-hexa-n-octylnitrilotriacetamide (HONTA) extractant, N',N'-di-n-hexyl-thiodiglycolamide (Crea) extractant, and macroporous silica polymer composite particles (SiO₂-P). The performance of platinum-group metals adsorption and separation on prepared (HONTA + Crea)/SiO₂-P adsorbent was then assessed together with that of co-existing metal ions by batch-adsorption and chromatographic separation studies. From the batch-adsorption experiment results, (HONTA + Crea)/SiO₂-P adsorbent showed high adsorption performance of Pd(II) owing to an affinity between Pd(II) and Crea extractant based on the Hard and Soft Acids and Bases theory. Additionally, significant adsorption performance was observed toward Zr(IV) and Mo(VI). Compared with studies using the Crea extractant, the high adsorption performance of Zr(IV) and Mo(VI) is attributed to the HONTA extractant. As revealed from the chromatographic experiment results, most of Pd(II) was recovered from the feed solution using 0.2 M thiourea in 0.1 M HNO₃. Additionally, the possibility of recovery of Zr(IV), Mo(VI), and Re(VII) was observed using the (HONTA + Crea)/SiO₂-P adsorbent.

• Korean Journal of Environment and Ecology
• /
• v.26 no.4
• /
• pp.528-536
• /
• 2012

This study has compared the different types of forest fires(unburned, crown fire, ground fire) and the degree of vegetation recovery at Samcheuk-si, Gangwon-do by assessing the biomass and net primary production from July 2007 through July 2010. The research showed that the average biomass of unburned site(Un), crown fire site(C-1), crown fire site(C-3), ground fire site(G-2) were $181.20{\pm}5.39$, $62.04{\pm}4.38$, $131.09{\pm}14.38$, $63.39{\pm}2.72ton{\cdot}ha^{-1}$, respectively. And the research showed that the average net primary production of unburned site(Un), crown fire site(C-1), crown fire site(C-3), ground fire site(G-2) were $4.17{\pm}0.56$, $3.27{\pm}1.56$, $11.51{\pm}0.53$, $2.10{\pm}0.31ton{\cdot}ha^{-1}{\cdot}yr^{-1}$, respectively. Quercus mongolica $DH_{10}$(Diameter at the 10cm tree height) growth rate at each plot was compared to the crown fire site(C-1) in the annual average $1.21{\pm}0.55mm{\cdot}yr^{-1}$ at the speed of the fastest growth follows; showed crown fire site(C-3), ground fire site(G-2), unburned site(Un) appeared in the order. And that showed the growth rate of height was highest in the $15.43{\pm}4.57cm{\cdot}yr^{-1}$ at crown fire site(C-3), then the crown fire site(C-1), and ground fire site(G-2), and lowest in the unburned site(Un).

• Journal of Climate Change Research
• /
• v.4 no.1
• /
• pp.51-61
• /
• 2013

To address the problems associated with climate change and energy shortage, Korea has been making efforts to turn waste materials into usable energy. Due to the ongoing efforts to convert waste materials into energy, waste incineration is expanding to utilize the heat generated, and the subsequent greenhouse gas emissions from these waste material incineration are expected to increase. In this study, a municipal waste incineration plant that generates heat and electricity through heat recovery was selected as a subject facility. Methods for estimating the greenhouse gas emissions in the municipal waste incineration plant that was selected as a subject plant were sought, and the greenhouse gas emissions and emission factor were estimated. The $CO_2$ concentrations in discharge gas from the subject facility were on average 6.99%, and the result from calculating this into greenhouse gas emissions showed that the total amount of emissions was $254.60ton\;CO_2/day$. The net emissions, excluding the amount of greenhouse gas emitted from biomass incineration, was shown to be $110.59ton\;CO_2/day$. In addition, after estimating the emissions by separating the heat and electricity generated in the incineration facility, greenhouse gas emission factors were calculated using the greenhouse gas emissions produced per each unit of output. The estimated emission factor for heat was found to be $0.047ton\;CO_2/GJ$ and the emission factor for electricity was found to be $0.652ton\;CO_2/MWh$. The estimated emission factor was shown to be about 17% lower than the $0.783ton\;CO_2/MWh$ emission factor for thermal power plants that use fossil fuels. Waste material types and fossil carbon contents were evaluated as being the factors that have major effects on the greenhouse gas emissions and emission factor.

• Archives of Plastic Surgery
• /
• v.45 no.5
• /
• pp.449-457
• /
• 2018

Background Although previous studies have focused on determining prognostic and causative variables associated with fistula-related complications after head and neck reconstructive surgery, only a few studies have addressed preventive measures. Noting that pooled saliva complicates wound healing and precipitates fistula-related complications, we devised a continuous suction system to remove saliva during early postoperative recovery. Methods A continuous suction system was implemented in 20 patients after head and neck reconstructive surgery between January 2012 and October 2017. This group was compared to a control group of 16 patients at the same institution. The system was placed orally when the lesion was on the anterior side of the retromolar trigone area, and when glossectomy or resection of the mouth floor was performed. When the orohypopharynx and/or larynx were eradicated, the irrigation system was placed in the pharyngeal area. Results The mean follow-up period was $9.2{\pm}2.4$ months. The Hemovac system was applied for an average of 7.5 days. On average, 6.5 days were needed for the net drain output to fall below 10 mL. Complications were analyzed according to their causes and rates. A fistula occurred in two cases in the suction group. Compared to the control group, a significant difference was noted in the surgical site infection rate (P<0.031). Conclusions Clinical observations showed reduced saliva pooling and a reduction in the infection rate. This resulted in improved wound healing through the application of a continuous suction system.

• Clean Technology
• /
• v.17 no.2
• /
• pp.156-165
• /
• 2011

The process for bioethanol production from lignocellulosic biomass was studied through process simulation using PRO/II. Process integration was conducted with concentrated acid pretreatment, hydrolysis process, SMB (simulated moving bed chromatography) process and pervaporation process. Energy consumption could be minimized by the heat recovery process. In addition, material and energy balance were calculated based on the results from the simulation and literature data. A net production yield of 4.07 kg-biomass and energy consumption value of 3,572 kcal per 1 kg ethanol were calculated, which is indicating that 26% yield increase and 30% energy saving compared to the bioethanol production process with dilute-acid hydrolysis (SRI report). In order to make it possible, sugar conversion yield of cellulose and hemi-cellulose is to be reached up to 90% and fermentation of xylose needs to be developed. In order to reduce the energy consumption up to 30%, the concentration of acid solution after being separated by 5MB should exceed 20%. If acid/sugar separation by SMB process is to be practical, the bioethanol process designed in this study can be commercially feasible.

• Korean Journal of Ichthyology
• /
• v.23 no.3
• /
• pp.198-205
• /
• 2011

Early life history of the endangered species, Gobiobotia macrocephala was investigated to provide baseline data for biological characteristics and recovery. Adult fish were sampled by spoon net at Hongcheon-gun, Gangwon-do, Korea in April to June 2010. The female's eggs were obtained by injecting Ovaprim and fertilized by dry method in the laboratory. The mature eggs were slightly adhesive and transparent with greyish and average 0.89${\pm}$0.04mm in diameter. The hatching of the embryo took place in about 107 hours after fertilization under water temperature of 23$^{\circ}C$ and newly hatched larvae were average 4.6${\pm}$0.16mm in total length. At 4 days after hatching, they were average 6.1${\pm}$0.20mm in total length and their yolk sacs were completely absorbed. From 15 days after hatching, they entered the juvenile stage and reached at 8.6${\pm}$0.67mm in total length. At the 100 days after hatching, their band patterns and external form were similar to those of adults, and they averaged 31.5${\pm}$3.32mm in total length.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.5 no.2
• /
• pp.53-62
• /
• 2002

The objectives of this study were to understand the tolerance mechanism of woody plants to water stress and tolerance changes in relation to mycorrhizal formation. Lespedeza cyrtobotrya Miq. commonly used for erosion control in slopes were raised from seeds and transplanted to 120 plastic pots. Sixty pots received the top soil of a Fraxinus americana forest, while remaining 60 pots received the autoclaved top soil. The forest soil contained 1,200 spores per 100g of arbuscular endomycorrhizal fungus, mostly Glomus sp. The plants were raised outside with regular supply of water and mineral nutrients. Two kinds of water deficit treatment and a control were started at the middle of July : cyclic water deficit treatment with 3 cycles of sequential water stress at the point of xylem water potential of about -0.6, -0.6, and -1.7 MPa and recovery, and non-cyclic water deficit treatment with single water stress at about -1.5 MPa. The non-stressed plants received plenty of water throughout the period. In late August the plants were harvested for measurements of dry weight, N, P, carbohydrate contents, net photosynthesis and superoxide dismutase(SOD) activities. Both cyclic and non-cyclic water deficit treatments reduced dry weight by 60% and 40%, respectively, and reduced nitrogen absorption, while increased SOD activities. Water-stressed plants also showed increased carbohydrate contents in the leaves and lowered stomatal conductance. Mycorrhizal inoculation resulted in an average of 40% infection of roots and 2-3 times increase in P absorption in water-stressed as well as non-stressed plants. Mycorrhizal formation also increased shoot-root ratio. The results that SOD activities of water-stressed plants with mycorrhizal infection were significantly lower than those of non-mycorrhizal plants suggest the possibility of improvement of water-stressed condition by mycorrhizal formation. It was concluded that endomycorrhizal formation increased tolerance of Lespedeza cyrtobotrya seedlings to water stress.

• Asian-Australasian Journal of Animal Sciences
• /
• v.26 no.6
• /
• pp.856-863
• /
• 2013

An in vitro gas production technique was used in this study to elucidate the effect of two strains of active live yeast on methane ($CH_4$) production in the large intestinal content of pigs to provide an insight to whether active live yeast could suppress $CH_4$ production in the hindgut of pigs. Treatments used in this study include blank (no substrate and no live yeast cells), control (no live yeast cells) and yeast (YST) supplementation groups (supplemented with live yeast cells, YST1 or YST2). The yeast cultures contained $1.8{\times}10^{10}$ cells per g, which were added at the rates of 0.2 mg and 0.4 mg per ml of the fermented inoculum. Large intestinal contents were collected from 2 Duroc${\times}$Landrace${\times}$Yorkshire pigs, mixed with a phosphate buffer (1:2), and incubated anaerobically at $39^{\circ}C$ for 24 h using 500 mg substrate (dry matter (DM) basis). Total gas and $CH_4$ production decreased (p<0.05) with supplementation of yeast. The methane production reduction potential (MRP) was calculated by assuming net methane concentration for the control as 100%. The MRP of yeast 2 was more than 25%. Compared with the control group, in vitro DM digestibility (IVDMD) and total volatile fatty acids (VFA) concentration increased (p<0.05) in 0.4 mg/ml YST1 and 0.2 mg/ml YST2 supplementation groups. Proportion of propionate, butyrate and valerate increased (p<0.05), but that of acetate decreased (p<0.05), which led to a decreased (p<0.05) acetate: propionate (A: P) ratio in the both YST2 treatments and the 0.4 mg/ml YST 1 supplementation groups. Hydrogen recovery decreased (p<0.05) with yeast supplementation. Quantity of methanogenic archaea per milliliter of inoculum decreased (p<0.05) with yeast supplementation after 24 h of incubation. Our results suggest that live yeast cells suppressed in vitro $CH_4$ production when inoculated into the large intestinal contents of pigs and shifted the fermentation pattern to favor propionate production together with an increased population of acetogenic bacteria, both of which serve as a competitive pathway for the available H2 resulting in the reduction of methanogenic archaea.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.29 no.4
• /
• pp.550-561
• /
• 2019

Objectives: The purpose of this study is to provide basic data for the improvement of the working environment for health prevention and related countermeasures for shift workers. This study was conducted based on the Fifth Korean Working Conditions Survey (KWCS), which analyzed the health effects of shift work forces and compared them with preceding studies. Methods: By analyzing secondary rates using raw data from the 5th KWCS, 4,870 (9.7%) of the 50,184 total study subjects were divided into shift work and 45,314 (90.3%) non-shift work groups based on the response to shift status. Variables that could affect work health issues were identified and corrected. A cross-analysis was conducted to examine demographic characteristics (gender, age, and education level) of the workers and occupation characteristics (monthly net earnings, employment type, occupation, working period up to now, workplace scale, type of work system, and weekly working hours). In order to find the work health issue ratio between the shift and non-shift work groups, logistic regression was analyzed and the association with health problems according to shift type by gender was looked at through cross-analysis. Results: According to the surveys conducted from the 1st KWCS (2006) to the 5th KWCS (2017), the proportion of shift workers continued to increase. Also, muscular pains in the lower limbs (hips, legs, knees, feet, etc.) (OR=1.135, 95%CI 1.031-1.251), headaches, eyestrain (OR=1.580, 95% CI 1.428-1.748), anxiety (OR=1.715, 95% CI 1.402-2.099), difficulty falling asleep (OR=1.391), and other problems (OR=7.392) were reported. In addition, back pain, muscular pains in shoulders, neck and/or upper limbs, muscular pains in lower limbs (hips, legs, knees, feet, etc.), headaches, eyestrain, depression, anxiety, overall fatigue resulted in significant results for both male and female shift workers. Depression and anxiety were higher in female shift/circulation compared to males. Conclusions: The social nets for the health and safety of shift workers should be explored in a variety of ways, including management and supervision of shift sites, attempts to reorganize and improve the shift system, development of workers' health recovery programs, promotion, systematic treatment, and compensation systems.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.17 no.4
• /
• pp.101-114
• /
• 2022

Recently, various studies on the entrepreneurial ecosystem have been conducted. The entrepreneurial ecosystem is composed of various elements such as entrepreneurs, governments, and infrastructure, and these factors interact to contribute to economic development. The purpose of this study was to analyze differences in importance and performance of the entrepreneurial ecosystem for startups using the importance-performance analysis (IPA) method. Based on this, the importance and current level of the components of the entrepreneurial ecosystem were identified and policy implications were presented. The results of the study are as follows. The importance ranking was in the order of startup support program(4.43), startup funding (4.39), market accessibility(4.30). The ranking of performance was startup support program(3.81), ease of starting a business(3.76), support for startup support institutions(3.66), and startup funding(3.66). All elements of the entrepreneurial ecosystem showed higher importance than performance. This means that the components of the entrepreneurial ecosystem in Korea are recognized as important, but do not play a significant role in terms of performance for startups. In addition, the factors with the highest improvement in the importance-performance matrix were 「safety nets for startup failure」, 「culture of acceptance of failure」, 「ease of market entry」, 「ease of startup survival」, and 「ease of exit」. This study suggested improvement measures such as establishing a social safety net, improving awareness of startup failure culture, matching successful startups, strengthening scale-up support by growth stage, easing regulations in new business fields, and diversifying investment recovery strategies.