• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.485-488
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• 2007

Riverbank filtration is a kind of artificial aquifer recharge for the fresh water supply. By construction of several production wells penetrating the riverbank, surface water withdrawn from the river would pass riverbed. This extracted water is well known to be cooler than surface water in summer and warmer than surface water in winter, showing more constant water temperature. This characteristic of extracted water is applied to geothermal energy utilization. Prediction of the annual temperature variation of filtrated water is the major concern in this study. In Daesan-myeon, Changwon-si, Gyeongsangnam-do, South Korea, riverbank filtration facility has been on its operation for municipal water supply and thermal energy utilization since 2006. Appropriate hydraulic and thermal properties were estimated for flow and heat transfer modeling with given pumping rate and location. With the calibrated material properties and boundary conditions, we numerically reproduced measured head and temperature variation with acceptable error range. In the numerical simulation, the change of saturation ratio and river stage caused by rainfall was calculated and the resulting variation of thermal capacity and thermal conductivity was considered. Simulated temperature profiles can be used to assess the possible efficiency of geothermal energy utilization using riverbank filtration facility. Influence of pumping rate, pumping location on the extracted water temperature will be studied.

• Health Policy and Management
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• v.30 no.1
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• pp.112-119
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• 2020

Suicide has been a long-standing problem for global public health, along with almost 800,000 deaths from suicide worldwide in 2016, accounting for 1.4% of all deaths. South Korea was ranked first in suicide mortality in 2018 among countries in the Organization for Economic Cooperation and Development. This study aimed to suggest up-to-date information about suicide-related indicators such as the rate of suicidal ideation, suicide attempt, and suicide death, and its trends by applying sampling weight to make it nationally representative. In this study, we used the data sources: Korea National Health and Nutrition Examination (KNHANES, '07-13, '15-18), Korean Community Health Survey (KCHS, '08-09, '13, '17), Korean Wealth Panel Study (KOWEPS, '12-18), Korea Health Panel Survey (KHP, '10-13), and Statistics Korea (1983-2017). The rate of suicidal ideation as recent year was 4.73% (KNHANES, '17), 6.96% (KCHS, '17), 2.29% (KOWEPS, '18), and 5.39% (KHP, '13). That of suicide attempt as recent year was 0.51% (KNHANES, '18), 0.32% (KCHS, '17), and 0.15% (KOWEPS, '18). Annual percentage change (APC) of suicidal ideation was -15.4% (KNHANES, '07-13, '15, '17), -2.5% (KCHS, '08-09, '13, '17), -10.8% (KOWEPS, '12-18), and -10.9% (KHP, '10-13). APC of suicide attempt was -4.4% (KNHANES, '07-13, '15-18), -4.4% (KCHS, '08-09, '13, '17), and -13.6% (KOWEPS, '12-18). APC of death by intentional self-harm was -1.25% (Statistics Korea, '07-18). All suicide-related indicators were found to be decreasing in the overall from 2009. Individuals with lower income level were more likely to experience suicidal ideation and suicide attempts. Even though suicide rate had been continuously decreasing from its highest point in 2011 (suicide rate: 31.7 per 100,000 population) to 2017 (suicide rate: 24.3 per 100,000 population), it increased again in 2018 (suicide rate: 26.6 per 100,000 population). This information would be grounded on policy implementation for suicide prevention, thus continuous data observation is necessary.

• Childhood Kidney Diseases
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• v.11 no.2
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• pp.239-246
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• 2007

Purpose : The progressive deterioration of renal function in children can impose a serious and lifelong impact on their lives. The ultimate goal in the management of children with chronic kidney disease(CKD) is to prolong survival, to prevent complications, and to promote growth and neurodevelopment. The aim of this study is to investigate the risk factors for the decline of renal function in pediatric CKD patients. Methods : Data from patients who met the criteria for the Kidney Disease Outcomes Quality Initiative(K/DOQI) CKD stage 2 to 4 between August 1999 and March 2007 were retrospectively analyzed. The estimated glomerular filtration rate(eGFR) was calculated by the Schwartz formula, using serum creatinine levels and height. We calculated the annual eGFR change from the difference between the baseline eGFR and the last eGFR divided by the duration(years) of the follow-up period. We analyzed the association between the annual eGFR change and factors such as age, gender, K/DOQI stage, underlying renal disease, serum calcium, and inorganic phosphorous during the follow-up period. Results : Sixty one children(44 boys & 17 girls) were enrolled. The age at entry was $7.1{\pm}4.7$ years. The annual eGFR change was $-1.2{\pm}11.9 mL/min/1.73m^2/year$. Our study showed that older age(P=0.005). hypocalcemia(P=0.012), and hypenhosphatemia(P=0.002) were significantly related to more rapid decline in renal function. Conclusion : In pediatric CKD, older age, hypocalcemia and hyperphosphatemia are related to more rapid deterioration of renal function.

• Journal of Ecology and Environment
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• v.41 no.12
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• pp.336-344
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• 2017

Background: Because of climate change, interest in the development of carbon pools has increased. In agricultural ecosystems, which can be more intensively managed than forests, measures to control carbon dioxide ($CO_2$) emission and absorption levels can be applied relatively easily. However, crop residues may be released into the atmosphere by decomposition or combustion. If we can develop scientific management techniques that enable these residues to be stocked on farmland, then it would be possible to convert farmlands from carbon emission sources to carbon pools. We analyzed and investigated soil respiration (Rs) rate characteristics according to input of carbonized residue of red peppers (Capsicum annuum L.), a widely grown crop in Korea, as a technique for increasing farmland carbon stock. Results: Rs rate in the carbonized biomass (CB) section was $226.7mg\;CO_2\;m^{-2}h^{-1}$, which was 18.1% lower than the $276.9mg\;CO_2\;m^{-2}h^{-1}$ from the red pepper residue biomass (RB) section. The Rs rate of the control was $184.1mg\;CO_2\;m^{-2}h^{-1}$. In the following year, Rs in the CB section was $204.0mg\;CO_2\;m{-2}h^{-1}$, which was 38.2% lower than the $330.1mg\;CO_2\;m^{-2}h^{-1}$ from the RB section; the control emitted $198.6mg\;CO_2\;m^{-2}h^{-1}$. Correlation between Rs and soil temperature ((Ts) at a depth of 5 cm) was $R^2=0.51$ in the RB section, which was higher than the other experimental sections. A comparison of annual decomposition rates between RB and CB showed a large difference, 41.4 and 9.7%, respectively. The results showed that carbonization of red pepper residues reduced the rates of decomposition and Rs. Conclusions: The present study confirmed that the Rs rate can be reduced by carbonization of residue biomass and putting it in the soil and that the Rs rate and Ts (5 cm) were positively correlated. Based on the results, it was determined that approximately $1.2t\;C\;ha^{-1}$ were sequestered in the soil in the first year and $3.0t\;C\;ha^{-1}$ were stored the following year. Therefore, approximately $1.5t\;C\;ha^{-1}year^{-1}$ are expected to be stocked in the soil, making it possible to develop farmlands into carbon pools.

• Korean Journal of Environment and Ecology
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• v.36 no.5
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• pp.496-506
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• 2022

The growth of trees planted through transplantation rapidly decreases immediately after planting due to extreme disturbances such as root cutting and crown damage. Although the growth rate is recovered as time elapses, the time required to restore the original growth varies by species. Therefore, it is necessary to set an appropriate tree management period for survival after transplantation by analyzing each species' annual growth change. In this study, we analyzed the growth amount of deciduous broad-leaf species planted in the area where the riparian ecological belt was formed and proposed the management period based on the results. Slowed growth immediately after planting is a common phenomenon due to root cutting and pruning, the pre-works performed to increase tree survival rate during the transplantation process. Afterward, the original growth rate is recovered as time passes, but the time required may vary depending on the species and planting environment. Most of the trees showed a rapid decrease in growth immediately after transplantation. After that, although it is different for each species, most of them showed a gradual recovery from 2 years onwards. The analysis of the growth rate by tree species confirmed that it took 2 to 4 years, depending on the tree species, to recover the growth level before transplantation after a rapid decrease in growth immediately after transplantation. The results suggest that improving the defect rate of planted trees is necessary to meet the project objectives: ecological restoration and pollutant reduction. It requires setting a tree management period of at least two years and creating an appropriate base environment.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.160-167
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• 1994

Meteorological elements such as air temperature, relative humidity, rainfall, sunshine duration, and so on observed by Korea Meteorological Administration, were analyzed to estimate the climatic change and to establish countermeasures in agriculture. Climatic differences were compared between two periods, early($1931{\sim}1960$) and late($1961{\sim}1990$), by calculating climatic resource indices, coldness index and warmth index of the two periods. Annual mean air temperatures of Seoul, Taegu, and Pusan in 1910's were 10.7, 12.3, and $13.4^{\circ}C$, respectively, having increased by $1.3^{\circ}C$ in Seoul and Taegu and by $0.9^{\circ}C$ in Pusan in 1990's. Mean air temperature in the spring($March{\sim}May$) increased by $0.69^{\circ}C$, which is a higher increasing rate than in the other seasons ($0.26{\sim}0.33^{\circ}C$). Regional differences exist in annual mean air temperature between the early and late part of the 20th century with little increase in this experiment did not germinate at pH 1.0. At pH 2.0, the flowering cabbage and geranium in the middle northern area, while in the southern part about $1^{\circ}C$increase was recorded during the last period. In the late period the annual rainfall increased by 100mm, except for the western coast area and the middle northern area. The P/E ratio showed a trend of an annual increase in the late period, being higher in the summer and lower in the winter. Relative humidity showed slight differences in seasons and regions but annual values did not. Duration of sunshine decreased by about an hour in the spring. Coldness index and warmth index of the late period were higher by 3.7 and 1.0 than those of the early period, respectively.

• Journal of Distribution Science
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• v.14 no.3
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• pp.73-83
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• 2016

Purpose - The parcel delivery service(courier) industry all over the world has been expanding its market so far, but its growth has been declining in recent years. In this situation, most parcel delivery companies are having trouble with managing themselves because of the pressure from the customer to increase service level and decrease the rate. The purpose of this study is to provide ways to improve competitive advantages of the parcel delivery service industry by evaluating the multi-period operating efficiency of Korea, Japan and global service providers. Research design, data, and methodology - The data for the period of 2011 to 2014 were collected from the annual reports published by parcel delivery companies. In this study, we analyze the marketability (revenue), profitability (operating profits), and management conditions (net profits) of parcel service companies by combining information on human resources (number of employees) and material resources (total assets and equity). Therefore, the number of employees, total assets, and equity are selected as input variables, and revenue, operating profits, and net profits as the output variables. In this study, DEA (Data Envelopment Analysis) is used to measure the comparative efficiency and MPI (Malmquist Productivity Index) is used to analyze the trend of change of the efficiency for a multi-year period. Results - The operational efficiency scores of medium-sized parcel delivery companies in Korea are higher than other larger competitors such as Korean, Japan and Global larger companies. As of 2014, Logen(1.878) was found to be the most efficient parcel delivery enterprise, followed by KGB (1.224), and Kyoungdong(1.002). Otherwise, Hanjin(0.235), CJ(0.262), Hyundai Logistics(0.657), DHL(0.611), UPS(0.766), FedEx(0.498), TNT(0.350), Yamato(0.762) and Sagawa(0.520), larger sized companies, were done inefficiently. The productivity of parcel delivery companies is influenced by endogenous factors as well as exogenous ones such as changes in business environment and technological advances. Conclusions - Korean medium-sized companies have relatively high efficiency scores in operation. That is why they still survive the competitive market in Korea where market restructuring on the industry has been expected to be conducted for many years. The reason why medium-sized couriers had higher efficient scores than larger couriers is that most of couriers spend more operating expenses versus unit price of delivery which is the amount of money that is needed in order to send a package by parcel service. So the delivery unit price must be taken into account by all the expenses associated with the cost of fuel, labor and maintenance expenses for facilities, etc. therefore, the unit price must be increased to strengthen business competitive power. In order for the industry to have more competitive advantage, the companies need to make profits by increasing demand volume and raising the delivery rate to provide high-quality delivery service to customers. And both endogenous and exogenous change must take precedence in order to strengthen their competitiveness.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.2
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• pp.123-129
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• 2011

A study on the occurrence and movement of marine debris is required for protecting the marine environment and ecosystem from marine pollution. The aim of this study is to show annual production and movement characteristics through analysis for the flow path, composition and the sources of marine debris. This study analyzed the distribution and characteristics of marine debris collected in the region of $100\;m{\times}20\;m$($=2,000\;m^2$) at the Daekwang Beach in the Yellow Sea. During the collection period from 2008 to 2010, the total weight of the marine debris was 1,445 kg in this site. The most marine debris was plastic amounting to 46.5% of the whole collection; the rest were styrofoam(20%) and wooden material(12.6%). The amount of marine debris mused from foreign country observed 155.5 kg, more than 90% of them was plastic came from China such as buoys. Additionally, this study analyzed seasonal change if marine environment to understand occurrence amount change if marine debris. 2009 and 2010 was high occurrence ratio in season that the north wind is very strong and the occurrence rate appeared highest by 40% in the summer(July) of 2008 that appeared westbound tidal current. Overall, marine Debris mused from foreign country was high occurrence ratio in January, May and then November has a lot of quantity secondly. While, occurrence ratio was the highest by 46% summer(July) in 2008, but in 2009 and 2010 showed the lowest rate to 4%.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.2
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• pp.229-238
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• 2023

The objective of this study was to investigate trends in ankyloglossia and its surgical treatment among pediatric patients in South Korea from 2011 to 2020. Data from Health Insurance Review and Assessment Service (HIRA)'s Healthcare Bigdata Hub were used for analysis of the ankyloglossia diagnosis rate and frenum surgery rate. Considering annual population change, crude rates per 100,000 were calculated and analyzed. To investigate other factors of frenum surgery incidence besides gender and age, pediatric patient sample data from HIRA were used. The diagnosis rate of ankyloglossia increased from 204.4 in 2011 to 356.6 per 100,000 people in 2020, while the frenum surgery rate increased from 26.8 to 34.3 per 100,000 people. Males were more likely to receive frenum surgery than females. Surgeries were more likely to be done at a hospital instead of a clinic or a general hospital. In the age group of 0 - 4 years, the largest number of frenum surgeries were performed in pediatrics, and in the age group of 5 - 9 years, the largest number of surgeries were conducted in pediatric dentistry. In the older age groups, the largest proportion of frenum surgeries were performed in the departments of conservative dentistry and oral and maxillofacial surgery. The diagnosis of ankyloglossia and the operation of frenum surgery among South Korean children increased during the last decade. Since the function of the tongue can affect maxillofacial development in many aspects, pediatric dentists should pay more attention to the functional management of intraoral soft tissue in growing children.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.566-573
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• 2016

The age-adjusted incidence rate (AAR) of colorectal cancer in Korea peaked in 2011 and then began to decline. However, the AAR of colorectal cancer in Jeju increased continually from 1999 to 2013. Compared with the 16 major cities in Korea, the inhabitants of Jeju-do have a low cancer screening program participation rate, high alcohol consumption rate and high BMI. The present study aimed to provide a statistical basis for the lowering of the incidence of colorectal cancer in Jeju-do. The Jeju regional cancer institute data from 1999 to 2013 was used to analyze the between Jeju-do and Korea using the Joinpoint Regression program (Statistical Methodology and Applications Branch, Surveillance Research Program, National Cancer Institute) Version 4.2.0 - April 2015. The AAR of colorectal cancer in Jeju-do has being increasing because of the increase in the rates of male colon cancer (average annual percent change 8.422%, p-value<0.000), female colon cancer (AAPC 6.136%, p-value<0.000), male rectal cancer (AAPC 4.221%, p-value 0.003) and colon cancer in people aged over 50 years (AAPC 7.986% p-value<0.000). The results of this study suggest that the treatment of precancerous lesions of the male rectum and lowering of the incidence of colon cancer in people aged over 50 years are necessary to reduce the colorectal cancer incidence rate in Jeju-do.