• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.313-324
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• 2011

The purpose of this study is to present the raw data for establishing the plan of top soil conservation in soil environment and preventing the soil loss by establishing the potential amount of soil loss using RUSLE. The results are as follows. To apply the RUSLE model, we calculated the potential amount of soil loss by using 5 factors; rainfall erosion factor(R), topographical factor(LS), soil erosion factor(K), land cover factor(C) and erosion control factor(P). The assessment map of soil loss was drawn up by classifying 5 grades. According to the soil loss estimation by the RUSLE, it showed that approximately 83.9% of the study area had relatively lower possibility of soil loss which was the 1 ton/ha in annual soil loss. Whereas, the 7.0% of the study area was defined as high risk area which was the 10 ton/ha in annual. Therefore, this area was needed that there was environment-friendly construction of farm land, improvement of cultivation environment and so forth. In future, if we will analyze the amount of soil loss of Gyeongju national park and Hyeongsan river watershed, we will offer the help to establishing the conservation plan of soil environment in Gyeongsangbuk-do.

• Journal of Biosystems Engineering
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• v.10 no.2
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• pp.1-11
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• 1985

A double pipe grain heater using engine exhaust gas as a heat source was developed. The performance of the grain heater was examined with soybeans as a test material experimentally and numerically using a mathematical model constructed. The following conclusions were drawn: 1. The modified screw conveyor used in the grain heater has a characteristic of decreasing capacity with increasing speed at speeds above 60 rpm. Operation with speeds below 60 rpm is recommended. 2. Heating soybeans by the heater at soybean flow rate up to 100 kg/hr, inlet temperature of the exhaust gas to the heater are recommended as above $400^{\circ}C$, $300^{\circ}C$, and $200^{\circ}C$ roughly for a 2, 5, and 10 kW engine, respectively. 3. Temperature increments of soybean by the heater at soybean flow rates ranged from 25 to 100 kg/hr are in the ranges of $6^{\circ}C-35^{\circ}C$, $15^{\circ}C-88^{\circ}C$, and $15^{\circ}C-140^{\circ}C$ with exhaust gas from a 2, 5, and 10 kW engine, respectively, at an exhaust temperature of $500^{\circ}C$. 4. Thermal efficiency of the heater at soybean flow rates ranged from 25 to 100 kg/hr are in the ranges of 35-37%, 28-34%, and 20-29% with exhaust gas from a 2, 5, and 10 kW engine, respectively. 5. The grain heater can be used to heat the other grain, also, without any bad effect from the exhaust gas used as a heat source.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.431-435
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• 2008

Thanks to the development of internet, on-line market expands exponentially and corresponding solid business models are drawn attentions. Most of on-line trading items are limited with selling game related items however, Linden Lab made its turning point by introducing cyber reality game to shape the cyber life with creating his own Avatar in 2003. After 2003, Second life has grown sharply that over 12 million users around the world. While former games are progressed within fixed scenario, the concept of avatars who live his or her own lives at the cyber space that successfully differentiate from former online game. Further, cyber money, Linden Dollar can be used to buy real estate, cloth, shoes just like at real economy system. Not only for using corporate marketing, various areas of activities; promotion of public sector, politics, education are also functioned at the cyber life. In Korea, Korean version of Second life was introduced at the end of 2007 that draws attentions from the users. In this study, I examine various business models of cyber through Second life and suggest feasible culture-contents applying models.

• Journal of Korean society of Dental Hygiene
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• v.18 no.2
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• pp.165-175
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• 2018

Objectives: This study aims to examine the factors that influence the organizational citizenship behavior of clinical dental hygienists to use them as basic data for improving effectiveness and efficiency of dental clinics and hospitals. Methods: A self-reported questionnaire was answered by 250 clinical dental hygienists in Seoul, Gyeonggi, Chungcheong, Jeolla and Gyeongsang province areas who were chosen using convenient sampling method from May 1st to June 30th of 2017. The data was analyzed using IBM SPSS/WIN 22.0 factor analysis on clinical dental hygienists' organization citizenship behavior, organizational commitment, empowerment, self-leadership and job satisfaction. T-test and one-way ANOVA were performed for subjects' general characteristics and organizational citizenship behavior, organizational commitment, empowerment, self-leadership and job satisfaction depending on their job characteristics. The mean comparison was drawn using the Scheffe test. Pearson's correlation and multiple regression analysis were performed to examine the relation of clinical dental hygienists' organizational citizenship behavior, organizational commitment, empowerment, self-leadership and job satisfaction Also, the significance level was set at 0.05. Results: Clinical dental hygienists' organizational citizenship behavior was 3.84 points with organizational commitment of 3.27, empowerment of 3.41, self-leadership 3.45 and job satisfaction of 3.57. Factors that influence clinical dental hygienists' organizational citizenship behavior appeared in the order of organizational commitment, job satisfaction, self-leadership, empowerment and job intensity, and the model's explanation power was 45.6%. Conclusions: Clinical dental hygienists' organizational citizenship behavior was correlated to career, organizational commitment, empowerment, self-leadership and job satisfaction, where organizational commitment had the biggest influence. Therefore, clinical dental hygienists organizational citizenship behavior needs further studies and investigtae more ways to promote factors that influence organizational citizenship behavior.

• Journal of Korean society of Dental Hygiene
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• v.18 no.2
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• pp.205-215
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• 2018

Objectives: The purpose of the study is to investigate the relationship between the number of remaining teeth and bone health status among adults over 65 years old. Methods: The study subjects were 1,843 adults over 65 years old drawn from the Korea National Health and Nutrition Examination Survey (KNHANES) in 2008-2010. Oral health status included the number of remaining teeth, and prosthetic appliance status. Bone health statuses were assessed using dual-energy X-ray absorptiometry (DEXA). Bone health statuses were classified into normal (T-score ${\geq}-1.0$), osteopenia (-2.5 < T-score < -1.0), and osteoporosis (T-score ${\leq}-2.5$). Complex samples chi-square test was used to estimate the relationship between the number of remaining teeth and bone health status, and related factors included in the model were analyzed with the complex samples logistic regression analysis. Results: Using the multinomial logistic regression analytic method, the elderly having 20 or more remaining teeth and those having less than 20 remaining teeth with prosthesis were compared. The latter group had 1.89 times higher rate of being diagnosed as having osteoporosis. Conclusions: This study suggests that oral health is an important factor for geriatric osteoporosis. Therefore, in order to prevent fractures due to osteoporosis and osteoporosis in old age, it is necessary to be aware of the relationship between oral health and osteoporosis, and oral health should be considered when preparing preventive management strategies.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.1
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• pp.17-28
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• 2011

This study was performed to ascertain the possibility of securing inflows to reservoir with low ratio of watershed to paddy field areas by outside diversion weir. The case of Maengdong reservoir and Samryong diversion weir was selected. Most of inflows to Maengdong reservoir with watershed area of $7.06\;km^2$ and total storage capacity of $1,269{\times}10^4\;m^3$ are filled with intake water from outside Samryong diversion weir. Only using water storage data in Maengdong reservoir from 1991 to 2009, the range of water intake in Samryong diversion weir to Maengdong reservoir was optimized to 0.135~30 mm/d, from which water intake to Maengdong reservoir was $1,672.9{\times}10^4\;m^3$ (70.1 %) and downstream outflow to Weonnam reservoir was $714.4{\times}10^4\;m^3$ (29.9 %). The parameters of DAWAST model for reservoir inflow were determined to UMAX of 313.8 mm, LMAX 20.3 mm, FC 136.8 mm, CP 0.018, and CE 0.007. Inflows to Maengdong reservoir were $427.1{\times}10^4\;m^3$ (20.3 %) from inside watershed, and $1,672.9{\times}10^4\;m^3$ (79.7 %) from outside. Paddy irrigation water requirements were estimated to $1,549{\times}10^4\;m^3$ on annual average. Operation rule curve was drawn by using daily inflow and irrigation requirement data. By securing the amount of inflow to Maengdong reservoir to about 80 % from outside Samryong diversion weir, water supply capacity for irrigation of $1,549{\times}10^4\;m^3/yr$ was analyzed to be enough. Additional water supplies for instream flow were analyzed to $1,412\;m^3/d$ in normal reservoir operation, $36,000\;m^3/d$ in withdrawal limit operation by operation rule curve from October to March of non irrigation period.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.251-262
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• 2003

LCP(Life Cycle Profiles) of bridge structures are indispensable for the LCC(Life Cycle Cost) evaluations of bridge system. The bridge under considerations may be newly-designed one or one in service. Thus, a systematic study of LCP is essential for both reliable LCC evaluation and strategic bridge management. LCP is mainly influenced by the structural environment in nature. However, in Korea, LCC evaluation has been performed with the LCP of foreign research results or only with the pieces of professional engineers' opinion. Therefore, to alleviate the drawbacks of foreign LCP and to enhance the reliability of current LCP, LCP should be established using the available data in bridge management system(BMS). In this study, LCP along with a subset of the BMS data was investigated and several mathematical expressions were proposed and evaluated. The condition ratings of a bridge were trasformed into the numerical indices through fuzzy logics with real field data. From the numerical results, it is concluded that the mathematical LCP model of $y=\sqrt{y^2_0-at}$ is shown to be the fittest one (R=0.815) to express the condition rating varied with the age. This has been drawn from the case study of slab bridges under the similar conditions.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.36-54
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• 1992

The purpose of this study was to compare the shear bond strengths to ground dentin surfaces of four dentinal bonding agents in 193 teeth. Various dentin surfaces treated with four dentin bonding agents were attached with two restorative composite resins. The effectiveness of the bonding were tested by the monitoring the shear bond strength. The shear bond strengths were measured after 2 hours and 24 hours after surface conditioning with four dentin bonding agents. Effects of EDTA, the additive illumination, and sealer treatments without primer on bond strength to dentin surfaces were assessed. In addition the effects of the thickness of specimens ranging from 0.65 mm to 1.95 mm and the ratio of catalyst and base paste on the bond strength of chemical cure composite resin were estimated. The shear bond strength was determined by testing specimens in the Instron universal testing machine (Model No. 1122) at a crosshead speed of 1.0 mm/min. Following condusions were drawn: 1. The highest mean shear bond strengths of chemical cure composite resin to dentin conditioning with dentin bonding agents aged 2 hours were obtained, and then that was decreased with time followed by EDTA treatment. 2. In light cure composite resin, the shear bond strength was increased following dentin conditioning with bonding agents with time, irradiation time and EDTA treatment except in SB group. 3. The thicker the composite resin specimen was, the less the shear bond strength in chemical cure composite resin was. 4. In light cure composite resin, there was a little change in shear bond strength following dentin conditioning with bonding agents. 5. In chemical cure composite resin, the shear bond strength was the highest in the ratio of 1/1 of catalyst and base part. 6. Without a dentin primer, shear bond strength to dentin conditioned only with UB sealer was the highest among four sealers in light cure composite resin.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.45-63
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• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.117-129
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• 2020

The purpose of this study is to verify the effect of the authentic leadership of social enterprise leaders on the happiness and job crafting of employees, the mediation effect of job crafting in the authentic leadership of the leader and the happiness of the employees, and the coordination effect by the Grit of the employees. For verification, the relationship between authentic leadership and job crafting, happiness and grit and seven research theories were established. In addition, 47 questionnaires were drawn through prior research on happiness, authentic leadership, job crafting, and grit, and five executives and workers of social enterprises in Chungcheongbuk-do(Province) were surveyed on a five-point Likert scale. The collected survey data were conducted through the SPSS and AMOS for basic statistical analysis. The Macro Process of the bootstrap method was used to verify the mediation effects, the regulated effects. This study has conducted exploratory and confirmatory factor analysis, correlation analysis, structural model analysis through the survey results and the analysis results verify the hypothesizes. The study found that authentic leadership affects the happiness and job crafting of employees, and that job crafting affects the happiness of employees, and the relationship between authentic leaders and employees affects job crafting. It has also been shown that the Grit of its employees affects their job crafting and happiness and also has a mediation effect on job crafting and happiness. In the policy environment of the changing rural development project, the social economy establishment plan for the virtuous circle of resources in the region should be considered, and education programs should be introduced to improve the authentic leadership of the leaders.