• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.357-367
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• 2022

Sleep disordered breathing (SDB) is a disease characterized by repeated hypopnea and apnea during sleep due to complete or partial obstruction of upper airway. The prevalence of pediatric SDB is approximately 12 - 15%, and the most common age group is preschool children aged 3 - 5 years. Children show more varied presentations, from snoring and frequent arousals to enuresis and hyperactivity. The main cause of pediatric SDB is obstruction of the upper airway related to enlarged tonsils and adenoids. If SDB is left untreated, it can cause complications such as learning difficulties, cognitive impairment, behavioral problems, cardiovascular disease, metabolic syndrome, and poor growth. Pediatric dentists are in a special position to identify children at risk for SDB. Pediatric dentists recognize clinical features related to SDB, and they should screen for SDB by using the pediatric sleep questionnaire (PSQ), lateral cephalometry radiograph, and portable sleep monitoring test and refer to sleep specialists. As a therapeutic approach, maxillary arch expansion treatment, mandible advancement device, and lingual frenectomy can be performed. Pediatric dentists should recognize that prolonged mouth breathing, lower tongue posture, and ankyloglossia can cause abnormal facial skeletal growth patterns and sleep problems. Pediatric dentists should be able to prevent these problems through early intervention.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.175-186
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• 2023

The buffer materials in disposal hole are exposed to the decay heat from spent nuclear fuels and groundwater inflow through adjacent rockmass. Since understanding of thermal-hydro-mechanical-chemical (T-H-M-C) interaction in buffer material is crucial for predicting their long-term performance and safety of disposal repository, it is necessary to investigate the heating-hydration characteristics and consequent T-H-M-C behavior of the buffer materials under disposal conditions considering geochemical factors. In response, the Korea Atomic Energy Research Institute developed a laboratory-scale 'Lab.THMC' experiment system, which characterizes the T-H-M behavior of buffer materials under different geochemical conditions by analyzing heating-hydration process and stress changes. This technical report introduces the detail design of the Lab.THMC system, summarizes preliminary experimental results, and outlines future research plans.

• Korea Trade Review
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• v.43 no.3
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• pp.125-145
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• 2018

The Baltic Shipping Exchange is reporting the Baltic Dry Index (BDI) which represents the average charter rate for bulk carriers transporting major cargoes such as iron ore, coal, grain, and so on. And the current BDI index is reflected in the proportion of capesize 40%, panamax 30% and spramax 30%. Like mentioned above, the capesize plays a major role among the various sizes of bulk carriers and this study is to analyze the influence of the factors influencing on charter rate of capesize carriers which transport iron ore and coal as the major cargoes. For this purpose, this study verified causality between variables using Vector Error Correction Model (VECM) and tried to derive a long-run equilibrium model between the dependent variable and independent variables. Regression analysis showed that every six independent variable has a significant effect on the capesize charter rate, even at the 1% level of significance. Charter rate decreases by 0.08% when capesize total fleet increases by 1%, charter rate increases by 0.04% when bunker oil price increases by 1%, and charter rate decreases by 0.01% when Yen/Dollar rate increases by 1%. And charter rate increases by 0.02% when global GDP increases by one unit (1%). In addition, the increase in cargo volume of iron ore and coal which are major transportation items of capesize carriers has also been shown to increase charter rates. Charter rate increases by 0.11% in case of 1% increase in iron ore cargo volume, and 0.09% in case of 1% increase in coal cargo volume. Although there have been some studies to analyze the influence of factors affecting the charterage of bulk carriers in the past, there have been few studies on the analysis of specific size vessels. At present moment when ship size is getting bigger, this study carried out research on capesize vessels, which are biggest among bulk carriers, and whose utilization is continuously increasing. This study is also expected to contribute to the establishment of trade policies for specific cargoes such as iron ore and coal.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.192-199
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• 2024

Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

• Journal of Korea Water Resources Association
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• v.57 no.3
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• pp.195-207
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• 2024

This study selected major drought events that occurred in the Jeonnam region from 1991 to 2023, examining both meteorological and hydrological drought occurrence mechanisms. The daily drought index was calculated using rainfall and dam storage as input data, and the drought propagation characteristics from meteorological drought to hydrological drought were analyzed. The characteristics of the 2022-23 drought, which recently occurred in the Jeonnam region and caused serious damage, were evaluated. Compared to historical droughts, the duration of the hydrological drought for 2022-2023 lasted 334 days, the second longest after 2017-2018, the drought severity was evaluated as the most severe at -1.76. As a result of a linked analysis of SPI (StandQardized Precipitation Index), and SRSI (Standardized Reservoir Storage Index), it is possible to suggest a proactive utilization for SPI(6) to respond to hydrological drought. Furthermore, by confirming the similarity between SRSI and SPI(12) in long-term drought monitoring, the applicability of SPI(12) to hydrological drought monitoring in ungauged basins was also confirmed. Through this study, it was confirmed that the long-term dryness that occurs during the summer rainy season can transition into a serious level of hydrological drought. Therefore, for preemptive drought response, it is necessary to use real-time monitoring results of various drought indices and understand the propagation phenomenon from meteorological-agricultural-hydrological drought to secure a sufficient drought response period.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.160-168
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• 2003

Purpose : To analyze the anterior stability and functional results after the arthroscopic ACL reconstruction and meniscectomy based on meniscus status at the time of surgery. Materials and Methods : From October 1997 to October 2002, 78 patients (male 64 female 14) were treated by arthroscopic ACL reconstruction and meniscectomy and followed more than 12 months (range, $12\~72$ months, average: 32 months). Average age was 32 years old (range, $18\~57$ years old). We divided the patients into 4 groups; Both menisci was intact (BMI, control group), lateral meniscus removed (LMR), medial meniscus removed (MMR) and both menisci removed (BMR). Anterior passive displacement (objective stability) was estimated using KT-2000 arthrometer under the loading of 15lb,20lb and 30lb and evaluated anterior drawer test, Lachman test, range of motion, thigh circumference. Functional evaluation system of IKDC, OAK and Lysholm knee score was used. Results : Average anterior displacement under the loading of 30lb were 2.47 mm, 2.96 mm, 2.96 mm and 3.57 mm in each group(BMI, LMR, MMR, BMR) and it was statistically significant difference (p<0.05). There is no statistically significant difference in average anterior displacement under the loading of 15lb and 20lb in each group but it has showed decreasing tendency in meniscal removed groups. The mean anterior displacement was within 3 mm in 21 cases, 15 cases, 24 cases and 12 cases (total 72 cases, $94\%$) under the loading of 15lb and 20 cases, 15 cases, 24 cases and 11 cases (total 70 cases, $91\%$) under the loading 20lb of in each group and postoperative knee joint stability has showed increasing tendency (p>0.05). The mean score was 94.5, 93.2, 92.2 and 90.4 points in each group and 71 cases $(91\%)$ were more than excellent or good with a OAK score and fair results were noted 4 cases in both meniscal removed group. There were 65 cases $(83\%)$ with a Lysholm knee score more than excellent or good, and IKDC grading were more than normal or nearly normal in 74 cases $(95\%)$ except 4 cases (2 cases in MMR group and 2 cases in BMR group). Conclusion : Long-term anterior stability and functional results of a successful ACL reconstruction affected by tile status of the menisci at the time of surgery and KT-2000 arthrometer was good for estimation of objective follow up.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.711-720
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• 2003

Bakground : Complete resection by the surgery has been selected as the treatment of choice in lung cancer patients, but in cases of recurrence after excision or inoperable cases, the importance of anticancer chemotherapy has been emphasized. If one can select a set of the sensitive chemotherapeutic agents before anticancer chemotherapy, it will give more favourable results. Subrenal capsular assay has been recognized as a useful in-vivo chemosensitivity test of thoracic and abdominal tumors and it can be done in a short time for a rapid interpretation of tumor responsiveness to anticancer chemotherapeutic drugs. It has been reported that various kinds of cancer cells can be implantable to the kidney, but so far there is no comparative study of xenogeneic cell implantation on liver, spleen and kidney. The author implanted the human lung cancer cells under the capsule of S.D rat's liver, spleen and kidney respectively and compared the pattern of growth and histology. Material and Method: After incubation of human lung cancer cell line (SW-900 G IV) in RPMI 1640 (Leibovitz L-15 medium) culture media, 3${\times}$3${\times}$3 mm size fibrin clots which contain 108 cancer cells were made. Thereafter the fibrin clots were implanted at subcapsule area of liver, spleen and kidney of S.D. female rat. For immune suppression, cyclosporin-A (80 mg/Kg) was injected subcutaneously daily from post-implantation first day to sixth day. The body weight was measured at pre and post implantation periods. The growth pattern and the size of tumor mass were observed and the pathologic examination and serum tumor marker tests were performed. Result: Body weight increased in both of control and experimental groups. Serum Cyfra 21-1 was not detected. Serum levels of CEA and NSE revealed no significant change. The SCC-Ag increased significantly in implanted group. The growth rate of human lung cancer cells which was implanted on spleen was higher than on liver or kidney. The surface area, thickness, and volume of tumor mass were predominant at spleen. The success rates of implantation were 80% on kidney, 76.7% on spleen and 43.3% on liver. Pathologic examination of implanted tumors showed characteristic findings according to different organs. Tumors that were implanted on kidney grew in a round shape, small and regular pattern. In the spleen, tumors grew well and microscopic neovascularization and tumor thrombi were also found, but the growth pattern was irregular representing frequent daughter mass. Human lung cancer cells that were implanted in the liver, invaded to the liver parenchyme, and had low success rate of implantation. Microscopically, coagulation necrosis and myxoid fibrous lesion were observed. Conclusion: The success rate of implantation was highest in the kidney. And the mass revealed regular growth that could be measured easily. The SCC-Ag was presented earlier than CEA or Cyfra21-1. The Cyfra21-1 was not detected at early time after implantation. The best model for tumor implantation experiment for chemosensitivity test was subrenal capsular analysis than liver and spleen and the useful serum tumor marker in early period of implantation was the SCC-Ag.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.123-131
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• 2009

Purpose: We tested a sample of nuclear medicine workers at Korean healthcare institutions for internal contamination with radioactive isotopes, measuring concentrations and evaluating doses of individual exposure. Materials and Methods: The detection and measurement was performed on urine samples collected from 25 nuclear medicine workers at three large hospitals located in Seoul. Urine samples were collected once a week, 100~200 mL samples were gathered up to 6~10 times weekly. A high-purity germanium detector was used to measure gamma radiations in urine samples for the presence of radioactive isotopes. Based on the detection results, we estimated the amounts of intake and committed effective doses using IMBA software. In cases where committed effective doses could not be adequately evaluated with IMBA software, we estimated individual committed effective doses for radionuclides with a very short half life such as $^{99m}Tc$ and $^{123}I$, using the methods recommended by International Atomic Energy Agency. Results: Radionuclides detected through the analysis of urine samples included $^{99m}Tc$, $^{123}I$, $^{131}I$ and $^{201}Tl$, as well as $^{18}F$, a nuclide used in Positron Emission Tomography examinations. The committed effective doses, calculated based on the radionuclide concentrations in urine samples, ranged from 0 to 5 mSv, but were, in the majority of cases, less than 1 mSv. The committed effective dose exceeded 1 mSv in three of the samples, and all three were workers directly handling radioactive sources. No nurses were found to have a committed effective dose in excess of 1 mSv. Conclusions: To improve the accuracy of results, it may be necessary to conduct a long-term study, performed over a time span wide enough to allow the clear determination of the influence of seasonal factors. A larger sample should also help increase the reliability of results. However, as most Korean nuclear medicine workers are currently not necessary to monitored routinely for internal contamination with radionuclides. Notwithstanding, a continuous effort is recommended to reduce any unnecessary exposure to radioactive substances, even if in inconsequential amounts, by regularly surveying workplace environments and frequently monitoring atmospheric concentrations of radionuclides.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.213-227
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• 2005

This study aims to assess the problems with investigation method and to suggest the complementary solutions by comparing the predicted data from surface investigation with the outcome data from underground cavern. In the study area, one(NE-1) of 6 fracture zones predicted during the surface investigation was only confirmed in underground caverns. Therefore, it is necessary to improve the confidence level for prediction. In this study, the fracture classification criteria was quantitatively suggested on the basis of the BHTV images of NE-1 fracture zone. The major orientation of background fractures in rock mass was changed at the depth of the storage cavern, the length and intensity were decreased. These characteristics result in the deviation of predieted predicted fracture properties and generate the investigation bias depending on the bore hole directions and investigated scales. The evaluation of hydraulic connectivity in the surface investigation stage needs to be analyze by the groundwater pressures and hydrochemical properties from the monitoring bore hole(s) equipped with a double completion or multi-packer system during the test bore hole is pumping or injecting. The hydraulic conductivities in geometric mean measured in the underground caverns are 2-3 times lower than those from the surface and furthermore the horizontal hydraulic conductivity in geometric mean is six times lower than the vertical one. To improve confidence level of the hydraulic conductivity, the orientation of test hole should be considered during the analysis of the hydraulic conductivity and the methodology of hydro-testing and interpretation should be based on the characteristics of rock mass and investigation purposes.

• Journal of Nutrition and Health
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• v.44 no.3
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• pp.231-242
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• 2011

The objective of this study was to investigate the effects of nutrition education based on ubiquitous healthcare (u-health) service on changes in dietary habits, nutrition intake, and risk factors for metabolic syndrome in male workers. In total, 72 male office workers with at least three risk factors of the National Cholesterol Education Program-Adult Treatment Panel III were recruited as subjects. Anthropometric measurements and biochemical analyses were conducted on all subjects. Dietary habits and nutrient intake were determined by a questionnaire using the 24-hour dietary recall method before and after nutrition education. Subjects measured their body composition, blood pressure, and physical activity more than once per week during the 12 weeks using the u-health care equipment and sent these data to a central database system using a personal computer. Individual nutrition counseling was provided four times on the first, fourth, eight, and twelfth weeks. The results showed significant decreases in abdominal circumference, body fat (%), diastolic blood pressure, serum triglycerides, and serum total cholesterol during the 12 weeks. Subjects with more than 12 measurements showed significant reductions in abdominal circumference, body fat (%), serum triglyceride, and serum total cholesterol. Mean intake of dietary fiber, animal calcium, potassium, vitamin C, and folic acid after nutrition education were higher than those before nutrition education. Participants showed significant increases in the frequencies of consuming protein foods (meat, fish, eggs, beans, tofu, etc.) and vegetables. In conclusion, nutrition education through the u-health service resulted in positive effects on the risk factors for metabolic syndrome, nutrient intake, and dietary habits.