• Analytical Science and Technology
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• v.22 no.4
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• pp.285-292
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• 2009

It has been observed that, after long term storage, some ammunitions are misfired by tamping (combustionstopping) due to aging of the chemicals loaded in the ammunitions. Used in ammunitions are percussion powder which provides the initial energy, igniter which ignites the percussion powder, and a delay system that delays the combustion for a period of time. The percussion powder is loaded first, followed by the igniter and then the delay system, and the ammunitions explode by the energy being transferred in the same order. Tamping occurs by combustion-stopping of the igniter or insufficient energy transfer from the igniter to the delay system or the combustion-stopping of the delay system, which are suspected to be caused by low purity of the components, inappropriate mixing ratio, size distribution of particulate components, type of the binder, blending method, hydrolysis by the humidity penetrated during the long term storage, and chemical changes of the components by high temperature. Goal of this study is to find the causes of the combustion-stopping of the igniter and the delay system of the ammunitions after long term storage. In this study, a method was developed for testing of the combustion-stopping, and the size distributions of the particulate components were analyzed with field-flow fractionation (FFF), and then the mechanism of chemical change during long term storage was investigated by thermal analysis (differential scanning calorimetry), XRD (X-ray diffractometry), and XPS (X-ray photoelectron spectroscopy). For the ignition system, M (metal)-O (oxygen) and M-OH peaks were observed at the oxygen's 1s position in the XPS spectrum. It was also found by XRD that $Fe_3O_4$ was produced. Thus it can be concluded that the combustion-stopping is caused by reduction in energy due to oxidation of the igniter.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.2
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• pp.83-90
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• 2023

The β-Ga₂O₃ has the most thermodynamically stable phase, a wide band gap of 4.8~4.9 eV and a high dielectric breakdown voltage of 8MV/cm. Due to such excellent electrical characteristics, this material as a power device material has been attracted much attention. Furthermore, the β-Ga₂O₃ has easy liquid phase growth method unlike materials such as SiC and GaN. However, since the grown pure β-Ga₂O₃ single crystal requires the intentionally controlled doping due to a low conductivity to be applied to a power device, the research on doping in β-Ga₂O₃ single crystal is definitely important. In this study, various source powders of un-doped, Sn 0.05 mol%, Sn 0.1 mol%, Sn 1.5 mol%, Sn 2 mol%, Sn 3 mol%-doped Ga₂O₃ were prepared by adding different mole ratios of SnO₂ powder to Ga₂O₃ powder, and β-Ga₂O₃ single crystals were grown by using an edge-defined Film-fed Growth (EFG) method. The crystal direction, crystal quality, optical, and electrical properties of the grown β-Ga₂O₃ single crystal were analyzed according to the Sn dopant content, and the property variation of β-Ga₂O₃ single crystal according to the Sn doping were extensively investigated.

• Journal of the Korean Society of Food Culture
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• v.21 no.1
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• pp.71-75
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• 2006

This study was conducted to investigate the eliminatory effect of health drink containing Hovenia dulcis Thunb extract on ethanol-induced hangover in rats. Male Sprague-Dawley rats weighing $200{\pm}10\;g$ were given health drink (10 mL/kg) or other company product(10 mL/kg) 30 min before or after 40% ethanol (5 g/kg body weight) ingestion. To study the effect of health drink on blood ethanol concentration, blood was taken from caudal artery at 1, 3, 5 hr and the animal were sacrificed 24 hr after ethanol ingestion. From 1 to 5 hr, health drink pre- or postdosing significantly decreased the ethanol levels in the blood. The acetaldehyde concentration showed decrement in health drink group and other company product group. The activities of ethanol, alcohol dehydrogenase and aldehyde dehydrogenase measured at postdosing, were also not altered by the administration of health drink. Alanine aminotransferase and aspartate aminotransferase activities showed unaltered resulted in all experimental groups compared with the normal group. These results suggest that oral intake of health drink containing Hovenia dulcis Thunb is effective on elimination of ethanol-induced hangover.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2B
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• pp.121-135
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• 2010

This study is to assess the effect of potential future climate change on the inflow of agricultural reservoir and its impact to downstream streamflow by reservoir operation for paddy irrigation water supply using the SLURP. Before the future analysis, the SLURP model was calibrated using the 6 years daily streamflow records (1998-200398 and validated using 3 years streamflow data (2004-200698 for a 366.5 $km^2$ watershed including two agricultural reservoirs (Geumgwang8 and Gosam98located in Anseongcheon watershed. The calibration and validation results showed that the model was able to simulate the daily streamflow well considering the reservoir operation for paddy irrigation and flood discharge, with a coefficient of determination and Nash-Sutcliffe efficiency ranging from s 7 to s 9 and 0.5 to s 8 respectively. Then, the future potential climate change impact was assessed using the future wthe fu data was downscaled by nge impFactor method throuih bias-correction, the future land uses wtre predicted by modified CA-Markov technique, and the future ve potentiacovfu information was predicted and considered by the linear regression bpowten mecthly NDVI from NOAA AVHRR ima ps and mecthly mean temperature. The future (2020s, 2050s and 2e 0s) reservoir inflow, the temporal changes of reservoir storaimpand its impact to downstream streamflow watershed wtre analyzed for the A2 and B2 climate change scenarios based on a base year (2005). At an annual temporal scale, the reservoir inflow and storaimpchange oue, anagricultural reservoir wtre projected to big decrease innautumnnunder all possiblmpcombinations of conditions. The future streamflow, soossmoosture and grounwater recharge decreased slightly, whtre as the evapotransporation was projected to increase largely for all possiblmpcombinations of the conditions. At last, this study was analysed contribution of weather, vegetation and land use change to assess which factor biggest impact on agricultural reservoir and stream watershed. As a result, weather change biggest impact on agricultural reservoir inflow, storage, streamflow, evapotranspiration, soil moisture and groundwater recharge.

• Journal of the Korean Society of Food Culture
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• v.21 no.1
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• pp.86-98
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• 2006

This study was conducted to investigate factors affecting bone density of food and nutrition vegetarian and non-vegetarian university students in Seoul area. Data for food habits, dietary and health-related behaviors were obtained by self administered questionnaires. BQI(bone quality index) of the subjects was measured by an Quantitative Ultrasound (QUS). The results are summarized as follows: The average height, weight, BMI and osteopenia percentage of the vegetarian and non-vegetarian male and female student were 172.61cm, 62.42kg, 20.98 and 24.2%; 175.38cm, 72.52kg, 23.71 and 16.7%; 160.47cm, 55.76kg, 21.66 and 55.9%; 161.77cm, 56.34kg, 21.53 and 37.6%, respectively. The BQI of the subjects were 101.73 and 107.43 in male student group, and 84.15, 89.64 in female student group, respectively. The BQI, Z-score value of bone density was significantly different in female group. Weight and BMI were positively related with BQI in male and female group. BQI was positively affected by nutrition supplement and negatively affected by seafood in vegetarian male student group. In vegetarian female student group, amount of meal was positively related with BQI and meal regularity was negatively related BQI. The result of this study revealed that the desirable food habits, dietary behaviors and health-related lifestyles may have a beneficial effect on bone density. They should have practically and systematically organized nutritional education on optimum body weight, good eating habits, weight bearing exercise and intakes of good quality nutrient for higher bone density level.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.565-575
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• 2009

In recent years, there have been numerous explosion-related accidents due to military and terrorist activities. Such incidents caused not only damages to structures but also human casualties, especially in urban areas. To protect structures and save human lives against explosion accidents, better understanding of the explosion effect on structures is needed. In an explosion, the blast load is applied to concrete structures as an impulsive load of extremely short duration with very high pressure and heat. Generally, concrete is known to have a relatively high blast resistance compared to other construction materials. However, normal strength concrete structures require higher strength to improve their resistance against impact and blast loads. Therefore, a new material with high-energy absorption capacity and high resistance to damage is needed for blast resistance design. Recently, Ultra High Strength Concrete(UHSC) and Reactive Powder Concrete(RPC) have been actively developed to significantly improve concrete strength. UHSC and RPC, can improve concrete strength, reduce member size and weight, and improve workability. High strength concrete are used to improve earthquake resistance and increase height and bridge span. Also, UHSC and RPC, can be implemented for blast resistance design of infrastructure susceptible to terror or impact such as 9.11 terror attack. Therefore, in this study, the blast tests are performed to investigate the behavior of UHSC and RPC slabs under blast loading. Blast wave characteristics including incident and reflected pressures as well as maximum and residual displacements and strains in steel and concrete surface are measured. Also, blast damages and failure modes were recorded for each specimen. From these tests, UHSC and RPC have shown to better blast explosions resistance compare to normal strength concrete.

• Exercise Science
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• v.21 no.2
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• pp.231-242
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• 2012

The purpose of this study was to develop the prediction model of VO₂max using submaximal metabolic responses from the Bruce protocol, HR responses at several stages and 1,200 m running record, and to compare and analyse the validity of these prediction models. The subjects were consisted of 255 male(133 male for 1,200 m running). They were participated maximal exercise testing with Bruce protocol, and the metabolic responses were measured in the end of the first(3 minute), second stage(6 minute), and 1,200 m running record. Measurement items were VO₂(㎖/kg/min), VCO₂(㎖/kg/min), VE(L/min), HR(bpm) of 3 and 6 minute, time to HR 150 bpm and 170 bpm, HR difference between Bruce protocol 6 and 3 minute, 1,200 m running record. Analyzing with all variables using enter method, the multiple R of total variable model was 0.642(p<.01), SEE was 4.38 ㎖/kg/min, CV was 10.8 %, but multicolinearity was appeared. The multiple R of 3 minutes model 1 and model 2 were 0.341 and 0.461, SEE was 6.05 and 5.72 ㎖/kg/min, CV was 14.9 and 14.1%, and multicolinearity did not appeared. The multiple R of 6 minutes model 1 and model 2 were 0.350 and 0.456, SEE was 6.03 and 5.74 ㎖/kg/min, CV was 14.9 and 14.2%, and multicolinearity did not appeared. The R of HR 170 and HR 170 model were 0.151 and 0.154, SEE were 6.36~6.37 ㎖/kg/min, CV were 15.7%. The R of 1,200 m running model was 0.444, SEE was 4.82 ㎖/kg/min, CV were 11.9%. In conclusion, with considering usefulness and convenience through the validity of these prediction models, the prediction model of VO₂max recommended 6 and 3 minute model, and the validity of HR model and 1,200 m running model were moderately low.

• Korean Journal of Legislative Studies
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• v.26 no.3
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• pp.37-83
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• 2020

This paper presents the results of 'The Survey on the 21^st National Assembly members' conducted by the Korean Association of Party Studies (KAPS) and the Hankyoreh following the 21^st Korean National Assembly Election. Since the 16^th Korean National Assembly Election, the KAPS has surveyed the candidates and/or the elected regarding their views on major policy issues and perceived self-ideology, which has contributed to our understanding of overtime changes in ideology of political parties in South Korea and their members. This year's survey includes 21 questions on the four major policy issue areas including foreign policy, economy, social issues and cultural issues as well as their perceived ideology. Among the 300 elected, 197 participated in the survey. The results suggest that the Justice Party is most liberal, the United Future Party is most conservative, and the Democratic Party is in the middle on average in terms of issue preference and perceived ideology. Compared to the preceding National Assembly, the partisan gap continues to appear salient in foreign policy, economy, and the cultural issues. In contrast, the gap narrows down in the social issues because the members of the Democratic Party embrace more conservative preference. It is noteworthy to examine whether this shift leads to cooperative decision making on social policies between liberal and conservative parties in the upcoming National Assembly. The composite policy preference index of individual assembly members, on the other hand, shows significant difference among members of different parties. Political parties in South Korea has evolved from a group of people from the same region into a group of people with distinctive policy preferences.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.29-40
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• 2019

In Korea kiwifruit growing area is limited to southern coastal region and Jeju island, partly due to the lack of information on their cold hardiness in winter. This study was carried out to investigate cold hardiness of Korean kiwifruit cultivars in a period of dormancy for using it as preliminary data to expand the cultivation area of kiwifruit in Korea. A total of five kiwifruit cultivars in two species and hybrid, Actinidia deliciosa ('Hayward' and 'Garmrok'), A. chinensis ('Goldone') and A. arguta hybrid ('Bangwoori' and 'Skinny Green') were subjected to five freezing treatments of -12℃, -15℃, -18℃, -21℃ and -24℃. Cell membrane damage in all cultivars initiated in -18℃/32h and cell membrane stability was lost in -24℃ in most cultivars, except for 'Skinny Green'. Cold hardiness was estimated by 50% lethal temperature (LT₅₀) which was determined by triphenyl tetrazolium chloride (TTC) reduction. In branches, LT₅₀ was -15℃ in 'Hayward' and 'Garmrok', -18℃ in 'Bangwoori' and -21℃ in 'Goldone.' The LT₅₀ of buds on 'Hayward' and 'Garmrok' was 56 and 42 hours in -15℃ and 4 and 11 hours in -18℃, respectively; however, LT₅₀ of buds on 'Goldone' was 51 hours in -18℃ and that on 'Bangwoori' was 3 hours in -24℃. Cold hardiness results imply that it may be difficult for cultivars in A. deliciosa such as 'Hayward' and 'Garmrok' to be grown in the north of southern coastal region in Korea; however, it can be possible for several cultivars in A. chinensis and A. arguta hybrid to be grown in the northern part of Korean kiwifruit belt if cold tolerance in the thaw is confirmed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.346-358
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• 2023

Due to the acceleration of climate change or global warming, it is important to predict rice productivity in the future and investigate physiological changes in rice plants. The research aimed to explore how rice adapts to climate change by examining the response of nitrogen absorption and nitrogen use efficiency in rice under elevated levels of carbon dioxide and temperature, utilizing the SPAR system for analysis. The temperature increased by +4.7 ℃ in comparison to the period from 2001 to 2010, while the carbon dioxide concentration was held steady at 800 ppm, aligning with South Korea's late 21st-century RCP8.5 scenario. Nitrogen was applied as fertilizer at rates of 0, 9, and 18 kg 10a^-1, respectively. Under conditions of climate change, there was an 81% increase in the number of panicles compared to the present situation. However, grain weight decreased by 38% as a result of reduction in the grain filling rate. BNUE, indicative of the nitrogen use efficiency in plant biomass, exhibited a high value under climate change conditions. However, both NUEg and ANUE, associated with grain production, experienced a notable and significant decrease. In comparison to the current conditions, nitrogen uptake in leaves and stems increased by 100% and 151%, respectively. However, there was a 25% decrease in nitrogen uptake in the panicle. Likewise, the nitrogen content and NDFF (Nitrogen Derived from Fertilizer) in the sink organs, namely leaves and roots, were elevated in comparison to current levels. Therefore, it is imperative to ensure resources by mitigating the decrease in ripening rates under climate change conditions. Moreover, there seems to be a requirement for follow-up research to enhance the flow of photosynthetic products under climate change conditions.