• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.199-207
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• 2016

This study was conducted to develop a forest fire occurrence model using meteorological characteristics for practical forecasting of forest fire danger rate by reflecting the climate change for the time period of 2000yrs. Forest fire in South Korea is highly influenced by humidity, wind speed, temperature, and precipitation. To effectively forecast forest fire occurrence, we developed a forest fire danger rating model using weather factors associated with forest fire in 2000yrs. Forest fire occurrence patterns were investigated statistically to develop a forest fire danger rating index using times series weather data sets collected from 76 meteorological observation centers. The data sets were used for 11 years from 2000 to 2010. Development of the national forest fire occurrence probability model used a logistic regression analysis with forest fire occurrence data and meteorological variables. Nine probability models for individual nine provinces including Jeju Island have been developed. The results of the statistical analysis show that the logistic models (p<0.05) strongly depends on the effective and relative humidity, temperature, wind speed, and rainfall. The results of verification showed that the probability of randomly selected fires ranges from 0.687 to 0.981, which represent a relatively high accuracy of the developed model. These findings may be beneficial to the policy makers in South Korea for the prevention of forest fires.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.3-4
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• 2000

Many researchers are interested in the synthesis and characterization of carbon nitride and diamond-like carbon (DLq because they show excellent mechanical properties such as low friction and high wear resistance and excellent electrical properties such as controllable electical resistivity and good field electron emission. We have deposited amorphous carbon nitride (a-C:N) thin films and DLC thin films by shielded arc ion plating (SAIP) and evaluated the structural and tribological properties. The application of appropriate negative bias on substrates is effective to increase the film hardness and wear resistance. This paper reports on the deposition and tribological OLC films in relation to the substrate bias voltage (Vs). films are compared with those of the OLC films. A high purity sintered graphite target was mounted on a cathode as a carbon source. Nitrogen or argon was introduced into a deposition chamber through each mass flow controller. After the initiation of an arc plasma at 60 A and 1 Pa, the target surface was heated and evaporated by the plasma. Carbon atoms and clusters evaporated from the target were ionized partially and reacted with activated nitrogen species, and a carbon nitride film was deposited onto a Si (100) substrate when we used nitrogen as a reactant gas. The surface of the growing film also reacted with activated nitrogen species. Carbon macropartic1es (0.1 -100 maicro-m) evaporated from the target at the same time were not ionized and did not react fully with nitrogen species. These macroparticles interfered with the formation of the carbon nitride film. Therefore we set a shielding plate made of stainless steel between the target and the substrate to trap the macropartic1es. This shielding method is very effective to prepare smooth a-CN films. We, therefore, call this method "shielded arc ion plating (SAIP)". For the deposition of DLC films we used argon instead of nitrogen. Films of about 150 nm in thickness were deposited onto Si substrates. Their structures, chemical compositions and chemical bonding states were analyzed by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Hardness of the films was measured with a nanointender interfaced with an atomic force microscope (AFM). A Berkovich-type diamond tip whose radius was less than 100 nm was used for the measurement. A force-displacement curve of each film was measured at a peak load force of 250 maicro-N. Load, hold and unload times for each indentation were 2.5, 0 and 2.5 s, respectively. Hardness of each film was determined from five force-displacement curves. Wear resistance of the films was analyzed as follows. First, each film surface was scanned with the diamond tip at a constant load force of 20 maicro-N. The tip scanning was repeated 30 times in a 1 urn-square region with 512 lines at a scanning rate of 2 um/ s. After this tip-scanning, the film surface was observed in the AFM mode at a constant force of 5 maicro-N with the same Berkovich-type tip. The hardness of a-CN films was less dependent on Vs. The hardness of the film deposited at Vs=O V in a nitrogen plasma was about 10 GPa and almost similar to that of Si. It slightly increased to 12 - 15 GPa when a bias voltage of -100 - -500 V was applied to the substrate with showing its maximum at Vs=-300 V. The film deposited at Vs=O V was least wear resistant which was consistent with its lowest hardness. The biased films became more wear resistant. Particularly the film deposited at Vs=-300 V showed remarkable wear resistance. Its wear depth was too shallow to be measured with AFM. On the other hand, the DLC film, deposited at Vs=-l00 V in an argon plasma, whose hardness was 35 GPa was obviously worn under the same wear test conditions. The a-C:N films show higher wear resistance than DLC films and are useful for wear resistant coatings on various mechanical and electronic parts.nic parts.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.2
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• pp.109-120
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• 2017

A discounted cost model for preventive maintenance of armor units of rubble-mound breakwaters is mathematically derived by combining the deterioration model based on a discrete-time stochastic process of shock occurrence with the cost model of renewal process together. The discounted cost model of condition-based maintenance proposed in this paper can take into account the nonlinearity of cumulative damage process as well as the discounting effect of cost. By comparing the present results with the previous other results, the verification is carried out satisfactorily. In addition, it is known from the sensitivity analysis on variables related to the model that the more often preventive maintenance should be implemented, the more crucial the level of importance of system is. However, the tendency is shown in reverse as the interest rate is increased. Meanwhile, the present model has been applied to the armor units of rubble-mound breakwaters. The parameters of damage intensity function have been estimated through the time-dependent prediction of the expected cumulative damage level obtained from the sample path method. In particular, it is confirmed that the shock occurrences can be considered to be a discrete-time stochastic process by investigating the effects of uncertainty of the shock occurrences on the expected cumulative damage level with homogeneous Poisson process and doubly stochastic Poisson process that are the continuous-time stochastic processes. It can be also seen that the stochastic process of cumulative damage would depend directly on the design conditions, thus the preventive maintenance would be varied due to those. Finally, the optimal periods and scale for the preventive maintenance of armor units of rubble-mound breakwaters can be quantitatively determined with the failure limits, the levels of importance of structure, and the interest rates.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.3
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• pp.1-12
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• 2016

This study aimed to interpret the fundamental cause of road-kill occurrences and analyzed spatial characteristics of the road-kill locations from Route 44 in Seorak National Park, Korea. Logistic regression analysis was utilized for backward elimination on variables. Seorak National Park Service has constructed GIS-data of 81 road-kill occurrences from 2008 to 2013 and these data were assigned as dependent variables in this study. Considered as independent variables from previous studies and field surveys, vegetation age-class, distance to streams, coverage of fences and retaining walls, and distance to building sites were assigned as road-kill impact factors. The coverage of fences and retaining walls(-1.0135) was shown as the most influential factor whereas vegetation age-class(0.0001) was the least influential among all of the significant factor estimates. Accordingly, the rate of road-kill occurrence can increase as the distance to building sites and stream becomes closer and vegetation age-class becomes higher. The predictive accuracy of road-kill occurrence was shown to be 72.2% as a result of analysis, assuming as partial causes of road-kill occurrences reflecting spatial characteristics. This study can be regarded as beneficial to provide objective basis for spatial decision making including road-kill occurrence mitigation policies and plans in the future.

• Journal of Life Science
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• v.18 no.4
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• pp.522-529
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• 2008

High-temperature requirement A2(HtrA2) has been known as a human homologue of bacterial HtrA that has a molecular chaperone function. HtrA2 is mitochondrial serine protease that plays a significant role in regulating the apoptosis; however, the physiological function of HtrA2 still remains elusive. To establish experimental system for the investigation of new insights into the function of HtrA2 in mammalian cells, we first obtained $HtrA2^{+/+}$ and $HtrA2^{-/-}$ MEF cells lines and identified those cells based on the expression pattern and subcellular localization of HtrA2, using immunoblot and biochemical assays. Additionally, we observed that the morphological characteristics of $HtrA2^{-/-}$ MEF cells are different form those of $HtrA2^{+/+}$ MEF cells, showing a rounded shape instead of a typical fibroblast-like shape. Growth rate of $HtrA2^{-/-}$ MEF cells was also 1.4-fold higher than that of $HtrA2^{+/+}$ MEF cells at 36 hours. Furthermore, we verified both MEF cell lines induced caspsase-dependent cell death in response to apoptotic stimuli such as heat shock, staurosporine, and rotenone. The relationship between HtrA2 and heat shock-induced cell death is the first demonstration of the research field of HtrA2. Our study suggests that those MEF cell lines are suitable reagents to further investigate the molecular mechanism by which HtrA2 regulates the balance between cell death and survival.

• Journal of fish pathology
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• v.31 no.1
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• pp.41-48
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• 2018

The utility of Bacillus spp. organisms for reduction of dissolved hydrogen sulfide ($H_2S$) in white leg shrimp (Litopenaeus vannamei) culture was tested with different combinations of Bacillus spp. microorganisms: combination A (B. subtilis + B. licheniformis); combination B (B. licheniformis + B. amyloliquefaciens); combination C (B. subtilis + B. licheniformis + B. amyloliquefaciens). Of these 3 combinations, C was effective in few hours after addition whereas B needed longer time to be effective. The $H_2S-reducing$ effect of combination C was dependent on the amount of microorganisms added to $H_2S-containing$ test solution. Exposure of white leg shrimp to $H_2S$ at 8 mg/L for 7 days led to survival of 80% and 1 mg/L for 14 days it was 82.5%. The survival rate was 97.5% when combination C was simultaneously added to shrimp tanks during $H_2S$ exposure at 1 mg/L for 14 days. It was demonstrated that combination C microorganisms (B. subtilis + B. licheniformis + B. amyloliquefaciens) can reduce dissolved $H_2S$ concentrations, and this effect can be utilized to protect white leg shrimp from $H_2S$ toxicity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1151-1158
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• 2006

This study was performed to investigate the effect of ethanol extract of Pimpinella brachycarpa (PB) on serum and liver lipid metabolism in rats. Male Sprague Dawley rats were administered 1% cholesterol and 0.25% sodium cholate to induce hypercholesterolemia. PB ethanol extract (200 mg/kg/day or 400 mg/kg/day) was also administered orally to rats with high cholesterol diet for 6 weeks. We divided 40 rats into five groups; normal diet group (NC), high cholesterol diet group (HC), normal diet and PB ethanol extract (200 mg/kg) administered group (NC-PB), high cholesterol diet and PB ethanol extract (200 mg/kg) administered group (HC-PBL), and high cholesterol diet and PB ethanol extract (400 mg/kg) administered group (HC-PBH). The growth rate and liver weight of the high cholesterol diet group was higher than those of the normal diet group, whereas those of the groups administered PB ethanol extract were gradually decreased. There was a signigicant increase in the activities of serum alanine aminotransferase (ALT), asparate aminotransferase (AST) and alkaline phosphatase (ALP) in the high cholesterol diet group. The administration of PB ethanol extract decreased serum ALT, AST and ALP activities in a dose-dependent manners. The high cholesterol diet group showed increased serum triglyceride, total cholesterol, free cholesterol and LDL-cholesterol levels, and decreased atherogenic index, HDL-cholesterol and phospholipid levels as compared with the normal diet group. PB ethanol extract administrated groups showed increased HDL-C/T-C, HDL-cholesterol and phospholipid levels, and decreased serum triglyceride, total cholesterol, free cholesterol, and LDL-cholesterol levels as compared with the high cholesterol diet group. There were no differences in the concentrations of serum triglyceride, phopholipid, LDL-cholesterol, HDL-cholesterol and free cholesterol between normal diet groups. The hepatic concentrations of total cholesterol and triglyceride were also lower in PB ethanol extract administrated groups than in the high cholesterol diet group. These results suggest that ethanol extract of PB exerts hypocholesterolemic effect by reducing serum and liver cholesterol contents.

• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.495-501
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• 2019

Aloin [1,8-Dihydroxy-10-(${\beta}$-D-glucopyranosyl)-3-(hydroxymethyl)-9(10H)-anthracenone], is a natural anthraquinone from aloe. It has been shown to have antioxidant and anticancer effects in various types of human cancer cells, but the anticancer effects of aloin in human colorectal cancer cells HT-29 have not been elucidated. In this study, possible mechanisms by which aloin exerts its apoptotic action in cultured human colorectal cancer HT-29 cells were investigated. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay shows that treatment with aloin (0, 100, 200, 300 and $400{\mu}M$) reduced cell viability in a concentration-dependent manner in HT-29 and showed no effects on cell proliferation in A375SM and AGS cells. In addition, it was confirmed that apoptotic body was significantly increased as shown by 4',6-diamidino-2-phenylindole (DAPI) staining, and increased apoptosis rate by flow cytometry in HT-29 cells treated with aloin (0, 200 and $400{\mu}M$). We confirmed by western blotting that aloin activated Bax (pro-apoptotic), cleaved-poly (ADP-ribose) polymerase (PARP) and caspase-3, -8 and Bcl-2 (anti-apoptotic) were not changed compared with the control. Aloin induced up-regulation of phospho-p38 and down-regulation of phospho-extracellular signal-regulated kinase (ERK)1/2. Therefore, aloin suppressed the growth inhibitory effects by the induction of apoptosis in human colorectal cancer cells and has potential as a cancer preventive medicine.

• Korean journal of applied entomology
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• v.58 no.2
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• pp.111-120
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• 2019

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) is an economically important insect pest of soybean and fruit trees. We investigated the temperature effects on the adult fecundity and longevity, and determined the parameters of oviposition models and life table at different constant temperatures 15.8, 19.7, 24.0, 27.8, 32.6, 34.0, and $35.5^{\circ}C$. R. pedestris females reproduced successfully from 19.7 to $35.5^{\circ}C$ except $15.8^{\circ}C$. The longevity of R. pedestris was longest at $15.8^{\circ}C$ and it decreased with increasing temperature (76.6 days at $19.7^{\circ}C$ and 20.6 days at $35.5^{\circ}C$). The number of total eggs and viable eggs was highest at $24.0^{\circ}C$ (193.5 and 151.2). Egg hatchability was highest at $27.8^{\circ}C$ (84.0%). We compared the results of oviposition models and life table parameters using both total eggs and viable eggs. The parameter value (c: the maximum reproductive capacity) (190 eggs) of temperature dependent total fecundity model using total eggs was higher than that of the model using viable eggs. When we analyzed the life table parameter the values of net reproductive rate and mean generation time using viable eggs were lower than those using total eggs. The oviposition models and life table analysis using viable eggs will be helpful to understand the real population transition of R. pedestris in agricultural system.

• The Southeast Asian review
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• v.27 no.1
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• pp.163-191
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• 2017

This article aims to review the recent, especially focusing on the year of 2016, situations and prospects of the Vietnamese politics, economy, and international relations. Politically, Vietnam completed the election of members for the National Assembly and organized new leadership at the 12th National Congress of the Vietnamese Communist Party in 2016. One characteristic of the new leadership is that the politicians, especially the members of politburo, from the North continue to occupy the position of majority. The other one is that the new leadership promised to carry out the restructuring of economy toward industries producing higher value-added commodities even though Vietnam industries admittedly need to accelerate present industrialization and modernization as a developing country under the seemingly contradictory slogan of "the development of market economy for socialism." The declared goals of the new leadership in Vietnam are inevitable in a sense since the development of Vietnamese economy has been heavily dependent upon Foreign Direct Investment(FDI) taking advantage of Vietnamese cheap labor and simultaneously it is evident that its future is unsecure if it maintains status quo. In fact, the Vietnamese economy has impressively showed high growth rate by the help of foreign capitals since 1990s despite the repetitive recessions of global economy but its growth is not likely to be sustainable anymore if it will not reduce foreign dependency and social economic inequality in a long term. In a short run, global economic recession, the financial and monetary policies of global powers, and recent protectionism and uncertainty of trade agreements will be three crucial variables to affect Vietnamese economy. In terms of international relations, Vietnam is continuously expected to practise the policy of checks and balances among the powerful countries. Vietnam has seriously disputed with China on islands sovereignty in the South China Sea and attempted to maintain close relationship with other powerful countries including especially America. However, mainly due to the new protectionism by the regime of American president Donald Trump, the Vietnamese government also need to keep close relationship with China increasingly for both economic and diplomatic security. Under the circumstances, Vietnam is expected to maintain more practical and balanced international relations.