• The Journal of Engineering Geology
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• v.33 no.4
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• pp.543-553
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• 2023

The current status of domestic a agalmatolite mines in South Korea was investigated with a view to establishing a stable supply of agalmatolite and managing its demand. Most mined agalmatolite deposits were formed through hydrothermal alteration of Mesozoic volcanic rocks. The physical characteristics of pyrophyllite, the main constituent mineral of agalmatolite, are as follows: specific gravity 2.65~2.90, hardness 1~2, density 1.60~1.80 g/cm³, refractoriness ≥29, and color white, gray, grayish white, grayish green, yellow, or yellowish green. Among the chemical components of domestic agalmatolite, SiO₂ and Al₂O₃ contents are respectively 58.2~67.2 and 23.1~28.8 wt.% for pyrophyllite, 49.2~72.6 and 16.5~31.0 wt.% for pyrophyllite + dickite, 45.1 and 23.3 wt.% for pyrophyllite + illite, 43.1~82.3 and 11.4~35.8 wt.% for illite, and 37.6~69.0 and 19.6~35.3 wt.% for dickite. Domestic agalmatolite mines are concentrated mainly in the southwest and southeast of the Korean Peninsula, with some occurring in the northeast. Twenty-one mines currently produce agalmatolite in South Korea, with reserves in the order of Jeonnam (45.6%) > Chungbuk (30.8%) > Gyeongnam (13.0%) > Gangwon (4.8%), and Gyeongbuk (4.8%). The top 10 agalmatolite-producing mines are in the order of the Central Resources Mine (37.9%) > Wando Mine (25.6%) > Naju Ceramic Mine (13.4%) > Cheongseok-Sajiwon Mine (5.4%) > Gyeongju Mine (5.0%) > Baekam Mine (5.0%) > Minkyung-Nohwado Mine (3.3%) > Bugok Mine (2.3%) > Jinhae Pylphin Mine (2.2%) > Bohae Mine. Agalmatolite has low thermal conductivity, thermal expansion, thermal deformation, and expansion coefficients, low bulk density, high heat and corrosion resistance, and high sterilization and insecticidal efficiency. Accordingly, it is used in fields such as refractory, ceramic, cement additive, sterilization, and insecticide manufacturing and in filling materials. Its scope of use is expanding to high-tech industries, such as water treatment ceramic membranes, diesel exhaust gas-reduction ceramic filters, glass fibers, and LCD panels.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.4
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• pp.1-15
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• 2016

Startups in Korea are experiencing for themselves the laws of survival through competition in the local and international market, and are performing active business movements based on these. Korea's economic growth rate is 2.6% due to the slump in the domestic demand and reduced exports brought by the MERSC incident in 2015. The Korea Development Institute has estimated the economic growth rate in 2016 to be around 3.0%. South Korea's economy is facing the crisis of low-growth solidification due to the decrease in economic growth, and it is forecasted that growth without employment and polarization will worsen. Startups in the high-tech industrial generation of a particular field wherein the market environment is rapidly changing must maintain a competitive advantage with the capabilities and functions exclusive to them. It is very important that they maintain a competitive edge by utilizing the capabilities exclusive to startup companies. Likewise, the accumulation of resources is also crucial in determining the success of a startup business. In a poor local startup ecosystem, majority of the startup companies are performing their business activities while striving for survival, rather than success. About 80% are struggling to survive and are failing to overcome the "Death Valley" faced 3-5 years after establishing the company. Since majority of the startups fail to achieve results during the initial stages of foundation, the importance of research on business activities and achievement during the early stages of establishment is being raised. In accordance to this, this research has performed an actual analysis on how the activities of startups during their preparation phase and early stages affect their achievements. A survey was done on the CEOs or executives (people in a position to make decisions) of local small and medium-sized enterprises that are considered start-ups, and 203 valid data were collected and analyzed. Results showed that the discoveries and utilized activities necessary for the businesses of startups have a significant impact on their achievement through the entrepreneur resources and external partners' cooperation; additionally, the related implications were discussed.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.47-56
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• 2008

Temporal changes of metal solubility have been repeatedly observed in soils equilibrated with metal salt solutions. This phenomenon is known as aging, yet factors that affect the degree of metal aging remain largely unexamined. In this study, we compared the extent of aging on metal partitioning depending on soil, metal, and metal loading. Five soils spiked with four levels of Cd (2.5-20 mg ${kg}^{-1}$), Cu, and Zn (50-400 mg ${kg}^{-1}$) salt solutions were aged in the laboratory up to 1 year. The partitioning coefficient ($K_d$) of each metal was calculated from the ratio of total to dissolved metal concentration in samples collected at times ranging from 1 day to 1 year. The highest $K_d$ values for Cd, Cu and Zn were recorded in a Histosol, Andisol, and fine-textured Alfisol, respectively, whereas the lowest $K_d$ was recorded for an Oxisol and coarsetextured Alfisol. For all soils, a pattern of increasing Kd with aging was evident for Cd and Zn, but not Cu. Rapid Cu sorption was limited when dissolved organic matter was high in soils. In highly-retentive soils, $K_d$ values seemed to be insensitive to metal loading, although a longer period was required for the higher metal loadings to reach the same degree of metal aging as the lower loadings. In soils with low sorption capacity, the $K_d$ values were determined more by metal loading than by aging. Therefore, marked differences can be expected in the degree of metal aging in spiked soils by the soil type, metal and amount of metal added.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.8-15
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• 2007

The morphology of gonad and reproductive cycle of ribbed gunnel (Dictyosoma burgeri) were investigated on the basis of histological observation. The specimens were monthly sampled in the coastal waters of Jeju from November 2001 to February 2003. The ovaries and testis of this species are categorized as cystovarian and lobule type, respectively. The gonadosomatic index (GSI) of female increased in November and maintained high values from December to February. The GSI of male was similar to that of female although it was decreased in February. The reproductive cycle can be grouped into the following successive stage in the ovary: growth (October to November), mature (November to February), spawning (January to February), and degenerating and recovery (March to September). And in the testis, the stage observed were: multiplication (August to November), growth (November to January), mature and spawning (November to February), and degenerating and recovery (January to September). The minimum maturation size of D. burgeri was over 15.0 cm and fecundity ranged from 2,194 to 6,581 eggs. The relationship between the fecundity and fish body was calculated in the fecundity (F) equation as: $F=0.4057TL^{3.1425}$ ($R^2=0.7621$) for total length (TL); $F=149.88BW^{0.9579}$ ($R^2=0.7982$) for body weight (BW), respectively. The fecundity was correlated positively with TL and BW. The histological observations of the gonads suggested that major spawning of this species probably occurs between January to February, when low water temperature ($13{\pm}0.3^{\circ}C$) period.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.207-220
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• 2012

There are around 7,500 manure tanks to treat the manures from pigs in Korea. In the tank, there are too much sediments deposited on the base and wall, which causes low efficiency of stock capacity and manure fermentation. In order to minimize sediments and to ferment manure effectively, we developed a 2-fluid jet mixer for mixing sediments in liquid livestock manure tank. For developing the prototype, we tested a factorial experimental system with various nozzles, and simulated CFD models with two kinds of nozzle arrangement. From the results of factorial experiment and CFD simulation, we concluded the dia. ratio of primary : secondary nozzle should be 1:2 and the nozzles should be arranged at the same distances toward to the circumferential direction. With this results, we manufactured a 2-fluid jet mixer which is consists of four 2-phase nozzles, centrifugal slurry pump and root's type air blower. And, we carried out the performance test of the prototype in the round shaped liquid manure tank in the farm. The performance test results showed that the uniformity of TS (Total Solid) and VS (Volatile Solid) was raised from 21.3 g/L, 13.3 g/L In steady state to TS and VS to 23.0 g/L, 14.1 g/L in the mixing operation. Therefore, we could conclude that the prototype of 2-fluid mixer could make the solid material which could be sediments in the tank not to be deposited in the tank and to be contacted to air bubbles which could enhance the efficiency of the fermentation of livestock manure.

• The Korean Journal of Food And Nutrition
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• v.25 no.1
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• pp.90-98
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• 2012

With the addition of ethanol to wax gourd extract and by acetic fermentation, 5.0% acidity vinegar was produced. After putting 10% extract(10% concentration) of Chrysanthemum zawadskii in this, and by dissolving shell, Chrysanthemum zawadskii-pearl vinegar was produced. When a 1% of ark shell, oyster shell, or ear shell was added to wax gourd vinegar, 95.6~98.4% of the shell dissolved, and when a 2% content of shell was added, 97.2~98.4% was dissolved. The acidity of vinegar which dissolved 1% shell was pH 3.0~3.17, and the acidity of vinegar which dissolved 2% shell was pH 1.11~ 1.20. The pH values of vinegar which dissolved 1%, and 2% shell contents were 4.54~4.55, and 4.86~4.95, respectively. When 1% shell was dissolved, the acidity was higher than that of commercial vinegar, with a high pH value and low level of free acid. This shows that when Chrysanthemum zawadskii 1% is added during acetic acid fermentation, the inhibition was 44.4%, and 22.2% respectively. In this regard, Chrysanthemum zawadskii should be added after the fermentation of acetic acid. The calcium content of 1% shell vinegar is 0.4%, and that of 2% vinegar is 0.78%. Non-heated native wax gourd shows an angiotensin converting enzyme inhibition rate of 21.7%, an antioxidant activity of 5.23%, and a tyrosinase inhibition rate of 5.5%. In the case of heated-extracted wax gourd, the angiotensin converting enzyme inhibition rate was 16.1%, superoxide dismutase activity was 20.5%, antioxidant activity was 23.2%, and the tyrosinase inhibition rate was 7.1%. Also, in the case of Chrysanthemum zawadskii, the angiotensin converting enzyme inhibition rate was 28.8%, the xanthine oxidase inhibition rate was 28.2%, the superoxide dismutase activity was 14.5%, the antioxidant activity was 3.2%, and the tyrosinase inhibition rate was 9.2% Data also revealed that when a 10% sample of the heated-wax gourd extract was added to A549 human lung cancer epithelial cells of, the number of cancer cells declined by 80% in 72 hours, When a 10% native extract was added, the number of cells declined by, 74% in 48 hours, and when a heated-extract of Chrysanthemum zawadskii was added, 100% of the cells died after 72 hours.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.7
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• pp.943-949
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• 2012

This study investigated the effects of diets with a supplement of Job's tears (JT) and Cudrania tricuspidata leaf (CTL) powder as a functional food ingredient on obesity and lipid profiles in diet-induced obese rats. Male Sprague-Dawley rats were fed a high-fat diet (D12492, 45 kcal fat) for 5 weeks during the first phase. In the second phase, which lasted 5 weeks, the rats were divided into four experimental groups. The groups were a high-fat diet group as a control (HFD), a high-fat diet with 10% JT powder supplement group (JT-10), a 10% CTL powder supplement group (CTL-10), and a 20% JT and CTL 1:1 mixed-powder supplement group (MIX-20). The adipose tissue (RFP, EFP) weights were significantly decreased in the CTL-10 and MIX-20 groups than in the HFD group (p<0.05). The fecal weight produced by the MIX-20 group was highest among all experimental groups (p<0.05), and it was significantly increased during the second phase compared to the first phase (p<0.05). The serum total cholesterol content was significantly decreased in the CTL-10 and MIX-20 groups, and the LDL-cholesterol content was significantly low in the JT-10 and MIX-20 groups than in the HFD group (p<0.05). The blood glucose levels were significantly decreased in all experimental diet supplement groups than in the HFD group (p<0.05). The findings show that a diet of mixed JT and CTL could improve lipid metabolism.

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.2
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• pp.151-158
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• 2011

This study was carried out in 2010 to investigate the utilization and nutritive value of native grasses, such as Phragmites communis and Miscanthus sinensis which might reduce the cost of feeding domestic cattle. The regions within the Civilian Control Line in Paju and Sihwa region in Ansan were surveyed. In Paju, the yearly silage production was 900 MT harvested from 90 ha (10 MT/ha). About 30~50% of these were sold out at the marketing price of 52,000~55,000 Won per roll (130~137.5 Won/kg). Regrown Miscanthus sinensis of 70 cm in length contained 9.6% of crude protein (CP), 82.4 of relative feed value (RFV), and 67.7% of in vitro dry matter digestibility (IVDMD). Regrown Phragmites communis of 70 cm in length contained 13.8% of CP, 84.3 of RFV, and 67.9% of IVDMD. As harvesting was delayed, the quality was decreased dramatically. In Ansan region, Phragmites communis plantation covers 100 ha. The silage production was 550 MT from the area of 50 ha (11 MT/ha) in 2009. And the marketing price was 50,000 Won per roll. But in 2010 only a small amount of grasses could have been baled due to frequent and much rainfall from spring to summer season. However, the good forage quality was observed from regrown Phragmites communis of 80 cm in length, 12.9% CP, 99.8 RFV and 66.6% IVDMD, while that of late matured grasses was very low, 2.2% CP, 52.9 RFV and 36.4% IVDMD, greatly lower than forage quality of rice straw. The quality of grasses at bloom stage of 150 cm in length was similar to that of rice straw, showing 4.5% CP, 59.9 RFV and 42.2% IVDMD. In conclusion, the overall quality of most native grasses in this survey were very poor. Therefore, we recommend that Phragmites communis and Miscanthus sinensis should be harvested during June or July to obtain better forage quality which is richer in forage values than rice straw. Production of high quality forage crops was also desirable for self sufficiency of forage.

• Journal of Intelligence and Information Systems
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• v.22 no.4
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• pp.157-176
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• 2016

For a long time, mobile phone had a sole function of communication. Recently however, abrupt innovations in technology allowed extension of the sphere in mobile phone activities. Development of technology enabled realization of almost computer-like environment even on a very small device. Such advancement yielded several forms of new high-tech devices such as smartphone and tablet PC, which quickly proliferated. Simultaneously with the diffusion of the mobile devices, mobile applications for those devices also prospered and soon became deeply penetrated in consumers' daily lives. Numerous mobile applications have been released in app stores yielding trillions of cumulative downloads. However, a big majority of the applications are disregarded from consumers. Even after the applications are purchased, they do not survive long in consumers' mobile devices and are soon abandoned. Nevertheless, it is imperative for both app developers and app-store operators to understand consumer behaviors and to develop marketing strategies aiming to make sustainable business by first increasing sales of mobile applications and by also designing surviving strategy for applications. Therefore, this research analyzes consumers' mobile application usage behavior in a frame of substitution/supplementary of application categories and several explanatory variables. Considering that consumers of mobile devices use multiple apps simultaneously, this research adopts multivariate probit models to explain mobile application usage behavior and to derive correlation between categories of applications for observing substitution/supplementary of application use. The research adopts several explanatory variables including sociodemographic data, user experiences of purchased applications that reflect future purchasing behavior of paid applications as well as consumer attitudes toward marketing efforts, variables representing consumer attitudes toward rating of the app and those representing consumer attitudes toward app-store promotion efforts (i.e., top developer badge and editor's choice badge). Results of this study can be explained in hedonic and utilitarian framework. Consumers who use hedonic applications, such as those of game and entertainment-related, are of young age with low education level. However, consumers who are old and have received higher education level prefer utilitarian application category such as life, information etc. There are disputable arguments over whether the users of SNS are hedonic or utilitarian. In our results, consumers who are younger and those with higher education level prefer using SNS category applications, which is in a middle of utilitarian and hedonic results. Also, applications that are directly related to tangible assets, such as banking, stock and mobile shopping, are only negatively related to experience of purchasing of paid app, meaning that consumers who put weights on tangible assets do not prefer buying paid application. Regarding categories, most correlations among categories are significantly positive. This is because someone who spend more time on mobile devices tends to use more applications. Game and entertainment category shows significant and positive correlation; however, there exists significantly negative correlation between game and information, as well as game and e-commerce categories of applications. Meanwhile, categories of game and SNS as well as game and finance have shown no significant correlations. This result clearly shows that mobile application usage behavior is quite clearly distinguishable - that the purpose of using mobile devices are polarized into utilitarian and hedonic purpose. This research proves several arguments that can only be explained by second-hand real data, not by survey data, and offers behavioral explanations of mobile application usage in consumers' perspectives. This research also shows substitution/supplementary patterns of consumer application usage, which then explain consumers' mobile application usage behaviors. However, this research has limitations in some points. Classification of categories itself is disputable, for classification is diverged among several studies. Therefore, there is a possibility of change in results depending on the classification. Lastly, although the data are collected in an individual application level, we reduce its observation into an individual level. Further research will be done to resolve these limitations.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.184-192
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• 2006

To investigate reproductive cycle of Tridentiger obscurus in Jeju, total 408 fish were collected in brackish area (May 2004 to August 2005) and total 271 fish were collected in tidal pool (July 2004 to August 2005), respectively. Water temperature ranged $11.0{\sim}21.6^{\circ}C$ in brackish area. Water temperature of tidal pool ($11.1{\sim}24.5^{\circ}C$) in 2005 was similar to that of brackish area although it were highest $30.1{\sim}29.2^{\circ}C$ from July to August in 2004. In brackish area, female gonadosomatic index (GSI) increased in April and maintained high values from May to August. The reproductive cycle can be grouped into the following successive stages in the ovary: immature (November to May), maturing (March to September), ripe and spawning (May to September), and degenerating (July to December). In the tidal pool, female GSI rapidly increased in April and maintained high values until July in 2005. However, it has been low in July 2004 when water temperature was highest. The reproductive cycle can be grouped into the following successive stages in the ovary: immature (August to April), maturing (March to August), ripe and spawning (March to July), and degenerating (July to August 2004 and August 2005). Fecundity of mature female ranged from 1,214 to 12,109 in brackish and ranged from 2,427 to 13,892 in tidal pool area. The fecundity of fish in the tidal pool was significantly higher than that of fish in brackish area. Fecundity was correlated positively with total length and body weigh. Although the large group (> 111 mm total length) in brackish area observed only in spawning season, one in the tidal pool observed from October 2004 until next spawning season. Frequency of the large group was 0 to 12% and 11.4 to 57.9% in brackish area and tidal pool, respectively. These results were indicated that gonadal development of T. obscurus was affected to water temperature and day length.