• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.603-616
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• 2007

Roy Huddle, having invented the coated particle in Harwell 1957, stated in the early 1970s that we know now everything about particles and coatings and should be going over to deal with other problems. This was on the occasion of the Dragon fuel performance information meeting London 1973: How wrong a genius be! It took until 1978 that really good particles were made in Germany, then during the Japanese HTTR production in the 1990s and finally the Chinese 2000-2001 campaign for HTR-10. Here, we present a review of history and present status. Today, good fuel is measured by different standards from the seventies: where $9*10^{-4}$ initial free heavy metal fraction was typical for early AVR carbide fuel and $3*10^{-4}$ initial free heavy metal fraction was acceptable for oxide fuel in THTR, we insist on values more than an order of magnitude below this value today. Half a percent of particle failure at the end-of-irradiation, another ancient standard, is not even acceptable today, even for the most severe accidents. While legislation and licensing has not changed, one of the reasons we insist on these improvements is the preference for passive systems rather than active controls of earlier times. After renewed HTGR interest, we are reporting about the start of new or reactivated coated particle work in several parts of the world, considering the aspects of designs/ traditional and new materials, manufacturing technologies/ quality control quality assurance, irradiation and accident performance, modeling and performance predictions, and fuel cycle aspects and spent fuel treatment. In very general terms, the coated particle should be strong, reliable, retentive, and affordable. These properties have to be quantified and will be eventually optimized for a specific application system. Results obtained so far indicate that the same particle can be used for steam cycle applications with $700-750^{\circ}C$ helium coolant gas exit, for gas turbine applications at $850-900^{\circ}C$ and for process heat/hydrogen generation applications with $950^{\circ}C$ outlet temperatures. There is a clear set of standards for modem high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a $500{\mu}m$ diameter $UO_2$ kernel of 10% enrichment is surrounded by a $100{\mu}m$ thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of $35{\mu}m$ thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum $1600^{\circ}C$ afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modem coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond $1600^{\circ}C$ for a short period of time. This work should proceed at both national and international level.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.361-371
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• 2000

It has been recently reported that 2-bromopropane (2-BP) induces male reproductive toxicity in both human and experimental animals. However, delayed effects of 2-BP on male reproductive system have not been investigated in detail. The present study was conducted to investigate the testicular toxicity of 2-BP and to determine the recovery of normal spermatogenesis in Sprague-Dawley rats. Male rats aged 5 weeks were administered 1,000mg/kg 2-BP by gavage daily for 4 weeks and sacrificed sequentially at 1, 2, 3, 4 and 12 weeks after initiation of 2-BP treatment. Testicular toxicity was evaluated qualitatively by histopathological examinations and quantitatively by reproductive organ weights, spermatid head count, and repopulation index. In the 2-BP treated rats, the body weights was significantly suppressed and the weights of testes and epididymides were also decreased in a time-dependent manner. On histopathological examination, spermatogonia in stages I-VI and preleptotene and leptotene spermatocytes in stages VII-IX were strongly depleted at 1 week of dosing. Spermatogonia were depleted extensively in all spermatogenic stages at 2 weeks. Continuing with the evolution of spermatogenic cycle, zygotene spermatocytes, pachytene spermatocytes, and round spermatids were sequentially depleted at 2, 3, and 4 weeks of dosing due to the depletion of their precursor cells. Vacuolization of Sertoli cells and spermatid retention were also observed at all time points, suggesting that 2-BP induced Sertoli cell dysfunction. At 12 weeks, after 8 weeks recovery, most of the tubules appeared severely atrophic and were lined by Sertoli cells only. Leydig cell hyperplasia in the interstitial tissue was also found. In addition, dramatic reductions in the number of spermatid heads and repopulation index were observed, indicating that 2-BP-induced testicular injury is irreversible. These results indicate that 4 weeks repeated-dose of 1,000mg/kg 2-BP results in a progressive germ cell loss due to the depletion of spermatogonia followed by long-term testicular atrophy in SD rats.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.414-420
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• 2012

In an effort to commercialization of energy saving aeration apparatus, panel-type aeration membranes were prepared from polyurethane sheet of J company in Korea having tensile strength higher than $400kg_f/cm^2$ with thickness of 0.5mm. Micropores of 100 m size were made by poring technique utilizing needles. From lab-tests in 450 L water tank at temperature of $20^{\circ}C$, the performance of aeration panels at 40 L/min aeration rate showed 5 mg/L DO in less than 3 minutes approaching saturation point of 8 mg/L within 8 minutes. The results show very high efficiency with $K_{La(15)}$ ($16.34hr^{-1}$), Standard oxygen transfer efficiency (SOTE 54.7%) and Standard aeration efficienct (SAE 7.88 kg/kwh). Other pilot scale test in a $2m^3$ water tank with water temperature ($19^{\circ}C$) and aeration rate (30 L/min) showed DO exceeding 5 mg/L within 8 minutes along with $K_{La(15)}$ ($5.8hr^{-1}$), SOTE (42.1%) and SAE (6.41 kg/kwh). These efficiencies represent 2~2.5 times higher than conventional aeration devices. Especially, the achievement of higher Oxygen Transfer Rate indicate higher commercial viability. Conventional aeration devices when applied to clean water and wastewater frequently cause problems due to differences in actual Oxygen Transfer Rate. Our actual tests with $40^{\circ}C$ animal farm wastewater resulted very high efficiencies with Oxygen transfer efficiency ($OTE_f$ 22.1%) and $OTE_{pw40}$ (39.6%).

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1310-1317
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• 2003

Effects of dietary cholesterol and/or taurine supplementation on plasma and hepatic lipid peroxidation status and antioxidant enzyme activities were evaluated in rats fed one of the following semisynthetic diets for 5 weeks: control diet (CD, cholesterol-free and taurine-free diet); high cholesterol diet (HCD, CD+1.5% cholesterol): high taurine diet (HTD, CD+1.5% taurine): high cholesterol and high taurine diet (HCHTD, HCD + 1.5% taurine). Plasma malondialdehyde (MDA) level was not influenced by dietary cholesterol or taurine supplementation, while hepatic MDA level was 70% higher in rats fed HCD compared to the value for CD rats (p<0.05). Our observation that taurine supplementation significantly decreased the hepatic MDA level of rats fed HCD, but failed to decrease lipid peroxidation of rats fed CD indicates that the protective effect of taurine in the liver against lipid peroxidation is manifested only under the hypercholesterolemic environment. Plasma and hepatic glutathione peroxidase (GSH-Px) activities were not affected by dietary supplementation of cholesterol or taurine. However, hepatic superoxide dismutase (SOD) activity was significantly reduced by dietary taurine supplementation (p <0.05), and thus significantly lower in rats fed HTD compared to the value for CD (p<0.05). Plasma total cholesterol concentration was positively correlated with hepatic cholesterol concentration as expected (r=0.712, p<0.001). Plasma (r=0.399, p<0.05) and hepatic cholesterol levels (r=0.429, p<0.05) showed a significantly positive correlation with hepatic MDA concentration, respectively. Plasma taurine concentration was negatively correlated with hepatic SOD activity (r=-0.481, p<0.01), and tended to be negatively correlated with hepatic GSH-Px activity without showing statistical significance (r=-0.188, p<0.05). These results indicate an antioxidative effect of taurine in rats with elevated level of lipid Peroxidation due to high intake of dietary cholesterol. Future application of taurine as a safe candidate for a hypolipidemic agent without adversely affecting body's antioxidant defense system is speculated.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.1
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• pp.47-55
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• 2009

In this study, the antioxidative effects, inhibitory effects on tyrosinase, and component analysis of fermented Melissa officinalis extracts were investigated. The ethyl acetate fraction of fermented extract ($8.38{\mu}g/mL$) showed the most prominent the free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities ($FSC_{50}$) of extract/fractions of M. officinalis. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of some M. officinalis extracts on ROS generated in $Fe^{3+}$-EDTA/$H_{2}O_{2}$ system were investigated using the luminol-dependent chemiluminescence assay. The ethyl acetate fraction of fermented extract ($0.63{\mu}g/mL$) showed the most prominent ROS scavenging activity. The protective effects of extract/fractions of M. officinalis on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The M. officinalis extracts suppressed photohemolysis in a concentration dependent manner ($5\;{\sim}\;75{\mu}g/mL$). The inhibitory effect of M. officinalis extracts on tyrosinase was investigated to assess their whitening efficacy. Inhibitory effects ($IC_{50}$) on tyrosinase of some M. officinalis extracts was 50 % ethanol extract ($365{\mu}g/mL$) < ethyl acetate fraction of fermented extract ($122.43{\mu}g/mL$) < ethylacetate fraction ($94.8{\mu}g/mL$). Fractions of ethyl acetate both from ordinary and fermented M. officinalis extracts showed 2 band in TLC and 2 peak in HPLC (330 nm). In HPLC chromatogram of ethyl acetate fraction, peak 1 (51.64 %) and peak 2 (48.36 %) were identified as caffeic acid and rosmarinic acid in the order of elution time. Also, in HPLC chromatogram of ethyl acetate fraction of fermented extract, peak 1 (4.13 %) and peak 2 (95.87 %) were identified as caffeic acid and rosmarinic acid in the order of elution time. These results indicate that the component and content of ordinary and fermented extracts of M. officinalis are different. And the extract of M. officinalis can be used as an antioxidant.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.4
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• pp.295-302
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• 2013

In this study, the antioxidative effects and inhibitory activities of unripened fruit extract of Rubus coreanus Miquel (R. coreanus Miquel) on tyrosinase were investigated and the potential applicability as a cosmeceutical ingredients was evaluated. All experiments were performed with 50% ethanol extract, ethyl acetate fraction and aglycone fraction of unripened fruit extract of R. coreanus Miquel. The DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activites ($FSC_{50}$) of 50% ethanol extract (6.56 ${\mu}g/mL$) and ethyl acetate fraction (6.14 ${\mu}g/mL$) of unripened fruit extract of R. coreanus Miquel were higher than (+)-${\alpha}$-tocopherol (8.98 ${\mu}g/mL$), which is known as a typical hydrophobic antioxidant. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of 50% ethanol extract (0.83 ${\mu}g/mL$), ethyl acetate fraction (0.84 ${\mu}g/mL$) and aglycone fraction (1.13 ${\mu}g/mL$) of R. coreanus Miquel on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were higher than L-ascorbic acid (1.5 ${\mu}g/mL$), which is known as s typical hydrophilic antioxidant. The cellular protective effect of extract and fraction of unripened fruit extract of R. coreanus Miquel on the rose bengal sensitized photohemolysis of human erythrocytes was increased in a concentration dependent manner (1 ~ 50 ${\mu}g/mL$). And 50% ethanol extract in 50 ${\mu}g/mL$ showed the most protective effect among extracts (${\tau}_{50}$ = 296.3 min). The inhibitory effects on tyrosinase of ethyl acetate and agylcone fractions were higher than arbutin. These results indicate that unripened fruit extracts of R. coreanus Miquel can be applied to antioxidant scavenging ROS including radical as an alternative whitening agent to replace arbutin.

• Journal of Acupuncture Research
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• v.22 no.1
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• pp.131-144
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• 2005

Objective : The aim of this study is to observe the effect of Herbal-acupuncture(HA) with Luffae Fructus Retinervus Herbal-Acupuncture Solution(LFR-HAS) at ST36(Joksamni) on Collagen Ⅱ -induced arthritis(CIA) in mice. Methods : DBA1/J mice were immunized with bovine type Ⅱ collagen(CⅡ) on days 0 and 21 to induce an arthritis. The mice were divided into 5 groups. They were Normal group(wild type), Control group(CIA), Saline group(CIA +saline injection), Needle Prick group(CIA +single Prick with an injection needle) and LFR-HA group(CIA +LFR-HA treatment). The saline injection, needle prick and LFR-HA were made on the right ST36(Joksamni) of mice for 5 weeks, 3 times a week beginning 4 weeks after the booster immunization. Results : 1. The highest synovial rate of lung fibroblasts was measured in the 1% LFR-HAS. 2. TNF-${\alpha}$ expression of survival cells from CIA mouse joint was significantly reduced in the 1% LFR-HAS. 3. The incidence of arthritis and the spleen weight of CIA mouse were significantly reduced by the Luffae Fructus Retinervus Herbal-Acupuncture (LFR-HA) at ST36. 4. The concentrations of IL-6, INF-${\alpha}$, INF-${\alpha}$, IgG, IgM, and anti-collagen Ⅱ in the CIA mouse serum were significantly reduced by the LFR-HA at ST36. 5. The histological examination showed that, in the LFR-HA group, the cartilage destruction and the synoviocyte proliferation in the CIA mouse joint were not significant compared to the control group, and the collagen fiber was similarly expressed as the normal group. 6. In the LFR-HA group, the ratio of CD3e+ to CD19+ cell, and the ratio of CD4+ to CD8+ cell in the lymph node were similarly maintained as those of the normal group. 7. CD69+/CD3e+ and CD11a+/CD19+ cells in the CIA mouse lymph node were significantly reduced by the LFR-HA at ST36. 8. CD11b+/Gr-1+ cells in the CIA mouse joint were significantly reduced by the LFR-HA at ST36. Conclusions : These results indicate that Luffae Fructus Retinervus Herbal-Acupuncture (LFR-HA) at ST36 may regulate the immune system and have a therapeutic effect on Collagen-induced arthritis(CIA) in mice.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.271-280
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• 2020

This study compared soil CO₂ efflux rates after fertilization, in Pinus densiflora and Quercus variabilis stands. Compound fertilizers were applied to the forest floor in March 2016, following a one-year calibration period (from March 2015 to February 2016). In situ soil CO₂ efflux rates were measured every month during the two-year study periods, using an infrared gas analyzer with a closed chamber system. Mean annual soil CO₂ efflux rates were higher following fertilizer application in the P. densiflora and Q. variabilis stands (P. densiflora: 2.180 μmol m^-2 s^-1; Q. variabilis: 1.977 μmol m^-2 s^-1) as compared with the rates measured during the calibration period (P. densiflora: 1.620 μmol m^-2 s^-1; Q. variabilis: 1.557 μmol m^-2 s^-1). The mean annual soil CO₂ efflux rates in the unfertilized treatments of both stands were not significantly different between the two-year study periods. The Q₁₀ values of fertilized treatments in Q. variabilis stands were higher in the fertilization period (3.41) than in the calibration period (3.14), whereas the Q₁₀ values in P. densiflora stands did not change between the fertilization and calibration periods. The Q₁₀ values of unfertilized treatments in the Q. variabilis stands were lower during the 2016-2017 period (3.69), than in the 2015-2016 period (3.85), whereas the Q₁₀ values in P. densiflora stands were higher during the 2016-2017 period (3.65), than in the 2015-2016 period (3.15). These results indicate that the increase in soil CO₂ efflux rates in P. densiflora stands could be more sensitive to fertilization compared with the rates in Q. variabilis stands.

• Journal of Global Scholars of Marketing Science
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• v.20 no.3
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• pp.249-261
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• 2010

As consumers' concern for the environment has continued to increase, many firms have actively engaged in environmental marketing to achieve their objectives. However, consumers' high concerns about the environment are not always reflected in their purchasing behavior. This indicates the need for an in-depth understanding of the development of green consumption within the individual's belief system. In consideration of psychological approaches, a large body of research has examined the factors underlying ecologically conscious "green" consumer behavior and the interrelationships of these factors. However, most previous studies have concentrated on Western countries. Using a sample of Korean consumers, this study attempts to understand the basis of Korean green consumerism and find universal values that are cross-culturally important in guiding consumers' environmental attitudes and behaviors. To this end, this study relates Schwartz's 10 universal values (Schwartz 1992) to environmental behaviors in a hierarchical model of value-attitude-behavior. With reference to the value-attitude-behavior framework, the conceptual model developed for the study explains what motivations can be manifested in Korean consumers' environmental attitudes, and subsequently how the attitudes affect their green choices. Using the pattern of relationships among values that can be related to environmentalism, the first hypothesis holds that there would be particular relationships between motivational value types and environmental attitudes. Hypothesis 2 assumes that environmental attitudes predict environmental behaviors. On the basis of the claim that favorable attitudes toward the environment may be expressed in many different behaviors, the assumption is that consumers' favorable attitudes toward the environment would be linked to a variety of environmental behaviors because people with high environmental attitudes can be more interested in and knowledgeable about environmental actions. Consistent with H2, H3 hypothesizes that there would be a positive relationship between different types of environmental behavior. A total of 564 university students participated in the study. The sample included 308 men, 254 women, and two participants who did not indicate their gender. The average age of the participants was 22.5 years, with a range of 19 to 39. Regarding majors, special efforts were made to draw the participants from different departments of the university. Data were collected by a survey administered via self-completion questionnaires., which assessed the participants' value priorities, environmental attitudes, and behaviors. Path analysis conducted to test the proposed model found the overall fit to be ${\chi}^2$=72.01 (p=0.00), GFI=0.983, CFI=0.982, NFI=0.970, RMR=0.070, and REMSEA=0.050. Thus, most of the fit measures indicated a good fit of the model with the data, and a hierarchical relationship from values to environmental attitudes to environmental non-purchasing behavior to environmental purchasing behavior was confirmed. An assessment of all the predicted paths by path coefficients led to several major hypothesized effects being confirmed. Out of the ten value types, universalism and power were significantly but conversely related to environmental attitudes. In line with the other studies, these findings confirm that environmental attitudes are an important factor in leading to a variety of green behaviors. Finally, significant relationships were found between environmental purchasing and non-purchasing behaviors. The path analysis supported the idea that universalism values provide a motivation for Korean consumers' greenness and indirectly promote environmental acts through favorable attitudes toward the environment. Participants with high environmental attitudes were found to actively engage in diverse forms of green consumer behavior. This research provides an opportunity to examine cross-cultural differences with respect to values leading to environmentalism, and, further, to verify previous findings. The study also examined the attitude-behavior relationship with respect to three distinct types of environmental behaviors. The different strengths of paths between green attitudes and behaviors suggest that researchers should consider the specificity of behavior explained as an effort to improve the low attitude-behavior correlation. Finally, the findings here illustrate that with increased environmental concerns among people, they come to include more such behaviors in their green portfolios.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.2
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• pp.125-134
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• 2009

In this study, the antioxidative effects, inhibitory effects on tyrosinase, and component of non-fermented and fermented Lavandula angustifolia extracts were investigated. The ethyl acetate fraction of fermented extract (5.95 ${\mu}g/mL$) showed the most prominent the free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of L. angustifolia extracts on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The ethyl acetate fraction of fermented extract (1.45 ${\mu}g/mL$) showed the most prominent ROS scavenging activity. The protective effects of extract/fractions of L. angustifolia on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The L. angustifolia extracts suppressed photohemolysis in a concentration dependent manner (1 ${\sim}$ 50 ${\mu}g/mL$). The inhibitory effect of L. angustifolia extracts on tyrosinase was investigated to assess their whitening efficacy. Inhibitory effects ($IC_{50}$) on tyrosinase were determined with ethyl acetate fraction of L. angustifolia extract (144.80 ${\mu}g/mL$) and ethyl acetate fraction of fermented extract (122.40 ${\mu}g/mL$). Fractions of ethyl acetate and fermented extracts showed both 3 band in TLC and 3 peaks, 2 peaks in HPLC (340 nm), respectively. In each chromatography, fractions of ethyl acetate both from non-fermented and fermented L. angusfifolia have rosmarinic acid in common. These results indicate that the component and content of non-fermented and fermented extracts of L. angustifolia are different. Both of the extract of L. angustifolia can be used as an antioxidant.