• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.245-245
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• 2015

In the recent years, due to long-lasting heavy rainfall events, a large number of landslides have been observed in the mountainous area of the world. Such landslides can also form a dam as it blocks the course of a river, which may burst and cause a catastrophic flood. Numerical analysis of landslide dam formation is rarely available, while laboratory experimental studies often use assumed shape to analyze the landslide dam failure and flood hydraulics in downstream. In this study, both experimental and numerical studies have been carried out to investigate the formation of landslide dam. Two case laboratory experiments were conducted in two flumes simultaneously. The first flume (2.0 m 0.6 m 0.5 m) was set at $22^{\circ}$ and $27^{\circ}$ slope to generate the landslide using rainfall intensity of 70.0 mm/hr. On the other hand, the second flume (1.5 m 0.25 m 0.3 m) was set perpendicularly at the downstream end of the first flume to receive the landslide mass forming landslide dam. The formation of landslide dam was observed at $15^{\circ}$ slope of the second flume. The whole processes including the landslide initiation and movement of the landslide mass into the second channel was captured by three digital cameras. In numerical analysis, a two-dimensional (2D) seepage flow model, a 2D slope stability model (Spencer method) and a 2D landslide dam-geometry evaluation model were coupled as a single unit. This developed model can determine the landslide occurrence time, the failure mass and the geometry of landslide dam deposited in the second channel. The data obtained from numerical simulation results has good agreement with the experimental measurements.

• 한국방재학회 논문집
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• 제11권3호
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• pp.127-132
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• 2011

본 연구에서는 강원도 인제군 산간지역에 대해 토사량 예측모형을 이용하여 산정한 토사량과 실제 준설량을 비교하였다. MSDPM과 LADMP를 한국지형에 맞게 보정하고 수정하여 사용하였다. 두 식 모두 토사 유발 강우강도와 토사 유발 강우량 개념을 도입하였으며 보정계수를 사용하여 식을 보정하였다. 계산 결과와 준설량을 비교한 결과, MSDPM의 계산결과가 LADMP보다 더 잘 일치하는 것으로 나타났다. MSDPM의 계산결과는 준설량과 약 27.6% 절대치 차이가 났으며 LADMP의 계산결과는 준설량과 약 50.6%의 절대치 차이를 나타냈다. 본 연구에서 보정된 두 개의 토사량 예측모형은 우리나라 산간지역의 토사량 예측을 위해서 사용 가능할 것으로 판단된다.

• The Journal of Advanced Prosthodontics
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• 제13권5호
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• pp.292-303
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• 2021

PURPOSE. The aim of this in vitro study was to evaluate the effect of silane and universal adhesive applications on the micro-shear bond strength (µSBS) of different resin-matrix ceramics (RMCs). MATERIALS AND METHODS. A total of 120 slides (14 × 12 × 1 mm) were produced from 5 different RMC materials (GC Cerasmart [GC]; Brilliant Crios [BC]; Grandio blocs [GB]; Katana Avencia [KA]; and KZR-CAD HR 2 [KZR]) and sandblasted using 50 ㎛ Al₂O₃ particles. Each RMC material was divided into six groups according to the surface conditioning (SC) method as follows: control (G1), silane primer (G2), silane-free universal adhesive (G3), silane-containing universal adhesive (G4), silane primer and silane-free universal adhesive (G5), and silane primer and silane-containing universal adhesive (G6). Three cylindric specimens made from resin cement (Bifix QM) were polymerized over the treated surface of each slide (n = 12). After thermal cycling (10000 cycles, 5 - 55℃), µSBS test was performed and failure types were evaluated using a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey tests (α = .05). RESULTS. µSBS values of specimens were significantly affected by the RMC type and SC protocols (P < .001) except the interaction (P = .119). Except for G2, all SC protocols showed a significant increase in µSBS values (P < .05). For all RMCs, the highest µSBS values were obtained in G4 and G6 groups. CONCLUSION. Only silane application did not affect the µSBS values regardless of the RMC type. Moreover, the application of a separate silane in addition to the universal adhesives did not improve the µSBS values. Silane-containing universal adhesive was found to be the best conditioning method for RMCs.

• 천문학회지
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• 제51권6호
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• pp.197-206
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• 2018

We present the analysis of KMT-2016-BLG-0212, a low flux-variation ($I_{flux-var}{\sim}20mag$) microlensing event, which is in a high-cadence (${\Gamma}=4hr^{-1}$) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf (q = 0.037) and sub-Neptune (q < $10^{-4}$) companions. Future high-resolution imaging should easily distinguish between these solutions.

• Nutrition Research and Practice
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• 제13권2호
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• pp.141-149
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• 2019

BACKGROUND/OBJECTIVES: This study examined the association between refined grain consumption by subtype and the incidence of hypertension from the Korean Genome and Epidemiology Study data. SUBJECTS/METHODS: In total, 5,018 participants (2,439 men and 2,579 women) from 40 to 69 years without hypertension were recruited at the beginning (2001-2002). Blood pressure and antihypertensive medication use were assessed biennially for the incidence of hypertension during the 8-year follow-up period (2009-2010). Hypertension was diagnosed as systolic blood pressure ${\geq}140mmHg$ or diastolic blood pressure ${\geq}90mmHg$ or antihypertensive medication use. Dietary intake including refined grains was assessed by a food frequency questionnaire at baseline and the follow-up (2005-2006). A multivariate Cox proportional hazard model was used to examine hazard ratios (HRs) and 95% confidence intervals (CIs) for incident hypertension according to refined-grain consumption. RESULTS: A total of 1,377 cases of hypertension (710 men and 667 women) were newly ascertained. Frequent noodle consumers (${\geq}5servings/week$) among the women had a 2.3-fold higher risk of hypertension than infrequent noodle consumers after adjustment for potential confounders (HR = 2.31, 95% CI = 1.33-4.01, P for trend = 0.0001). However, no significant association was found among the men. The intake of other refined grain products such as white rice and breads was not associated with the incidence of hypertension. CONCLUSION: Frequent noodle consumption was positively associated with a risk of incident hypertension in South Korean women.

• Journal of Korean Neurosurgical Society
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• 제62권2호
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• pp.256-262
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• 2019

Objective : Pituitary adenomas (PAs) are often detected as incidental findings. However, the natural history remains unclear. The objective of this study was to evaluate the natural history and growth pattern of untreated PAs. Methods : Between 2003 and 2014, 59 PAs were managed with clinico-radiological follow up for longer than 12 months without any kind of therapeutic intervention. Tumor volumes were calculated at initial and last follow-up visit, and tumor growth during the observation period was determined. Data were analyzed according to clinical and imaging characteristics. Results : The mean initial and last tumor volume and diameter were $1.83{\pm}2.97mL$ and $13.77{\pm}6.45mm$, $2.85{\pm}4.47mL$ and $15.75{\pm}8.08mm$, respectively. The mean annual tumor growth rate was $0.33{\pm}0.68mL/year$ during a mean observation period of $46.8{\pm}32.1months$. Sixteen (27%) PAs showed tumor growth. The initial tumor size (HR, 1.140; 95% confidence interval, 1.003-1.295; p=0.045) was the independent predictive factor that determined the tumor growth. Six patients (11%) of 56 conservatively managed non-symptomatic PAs underwent resection for aggravating visual symptoms with mean interval of 34.5 months from diagnosis. By Cox regression analysis, PAs of last longest diameter over 21.75 mm were a significant prognostic factor for eventual treatment. Conclusion : The initial tumor size of PAs was independently associated with the tumor growth. Six patients (11%) of conservatively managed PAs were likely to be treated eventually. PAs of last follow-up longest diameter over 21.75 mm were a significant prognostic factor for treatment. Further studies with a large series are required to determine treatment strategy.

• 한국물환경학회지
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• 제27권5호
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• pp.572-579
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• 2011

We have examined the runoff characteristics of nonpoint source (NPS) in fields. Two monitoring sites were equipped with an automatic velocity meter and water sampler. Monitoring was conducted at fields 1 and field 2 during the rainfall event. Ten rainfall-runoff events were monitored and analyzed during the study period. The results show that runoff occurred if daily rainfall and intensity were higher than 40 mm and 1.6 mm/hr except a few extreme rainfall events with very high intensity. Runoff of field 1 was approximately twice of that of field 2. Event mean concentrations (EMC) and pollution load of analyzed water quality indices were also higher in field 2 than in field 1. Especially, TN load from field 2 was $75.4 mg/m^2$ and was about 5 times higher than that from field 1. Analysis of Pearson correlation coefficient of water quality parameter indicates that besides of TN all items in fields 1 have tight relationship respectively (p < 0.01). But those of fields 2 have a significant (p < 0.05). Estimating units loading of NPS, we suggested that variable such as soil texture, rainfall amount and intensity and slope were needed to be considered from agricultural landuses. The results of this study can be used as a basic data in the development and implementation of total maximum daily loads (TMDL) in Korea.

• Animal Bioscience
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• 제34권4호
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• pp.759-769
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• 2021

Objective: This study aimed to investigate the effect of stocking density on the behavior, productivity, and metabolism of periparturient Holstein cows as well as calf performance. Methods: A total of 48 periparturient cows were randomly assigned into three groups at 28 days (±3 days) before their expected calving date. The stocking densities of the groups, relative to the standard cubicle and feed bunk number, were i) 80% (13 cows), ii) 100% (16 cows), and iii) 120% (19 cows). Lying and rumination behavior was recorded using electronic data loggers and HR-Tags from d -21 ("d-" means days before calving) until the calving date, d 0. Lying time was assessed to determine the diurnal total hours spent lying per day. Rumination time was averaged in 2 hours interval periods over 24 hours during the experimental period. Results: Cows in the 80% group spent more time lying and ruminating between d -21 and d -7 and tended to ruminate more between d -14 and d 0. Calcium levels tended to be higher for cows in the 80% group, no other observable differences were found in monitored blood parameters. Moreover, 3.5% fat corrected milk and energy corrected milk yields were higher in 80% group in the first month of lactation. No other observable differences were found in the yield and composition of colostrum and milk in the first 10 months of lactation. The growth and performance of calves in the first week of life was not affected by stocking density of the dams. Conclusion: We concluded that lower stocking density may increase lying and ruminating behavior of prepartum Holstein cows. However, this did not translate into improved productivity and metabolism.

• Natural Product Sciences
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• 제26권4호
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• pp.317-325
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• 2020

A new dimer stilbene [Monalittorin (1)] and ten known compounds [engeletin (2), aurantiamide acetate (3), lupeol (4), friedelin (5), quercetin (6), tiliroside (7), rutoside (8), astragalin (9), isoquercitrin (10) and quercimeritroside (11)] have been isolated from the leaves of Monanthotaxis littoralis (Annonaceae). The structures of these compounds were established by interpretation of their data, mainly, HR-TOFESIMS, 1-D NMR (1H and 13C) and 2-D NMR (1H-1H COSY, HSQC, HMBC and NOESY) and by comparison with the literature. The evaluation of their antimicrobial activities against three bacteria (Staphylococcus aureus ATCC 25923, Escherichia coli S2 (1) and Pseudomonas aeruginosa PA01) and three fungal strains (Candida albicans ATCC10231, Candida tropicalis PK233 and Cryptococcus neoformans H99) using broth micro dilution method, showed the largest antimicrobial activities of EtOAc fraction and compounds 1, 5, 6, 8 and 11 (MIC = 8 - 64 ㎍/mL). In addition, EtOAc fraction presented synergistic effect with Vancomycin and fluconazole against the tested microorganisms.

• 아태비즈니스연구
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• 제13권1호
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• pp.19-36
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• 2022

Purpose - Previous studies tried to find antecedents of innovative behavior. However, research on knowledge hiding behavior, psychological mechanism, and perception of organizational justice has been relatively limited. In this sense, this study has investigated the impact of organizational justice on employees' innovative behavior and explored the factors that affect the above relationship. Especially, this study tested the direct effect of organizational justice on innovative behavior. This study also examines the mediating roles of knowledge hiding behavior in this causal relationship. Moreover, the process of organizational justice to innovative behavior is assumed to be influenced by leadership style. Therefore, we examined the moderating effect of authentic leadership on the relationship between organizational justice and knowledge hiding behavior. Design/methodology/approach - For the empirical test, we collected data via a questionnaire survey of a sample of 252 employees from Korean firms. We conducted a hierarchical regression analysis to test hypotheses. Results - The results of the empirical analysis revealed that organizational justice was positively related to innovative behavior and negatively related to knowledge hiding behavior. The results also showed that knowledge hiding behavior negatively mediated the relationship between organizational justice and innovative behavior. In addition, we found the moderating role of authentic leadership. More importantly, we found that the conditional indirect effect of organizational justice on innovative behavior via knowledge hiding behavior was depending on authentic leadership. Uncovering the relationship between organizational justice and innovative behavior through the mediating role of knowledge hiding behavior and the moderated mediating role of authentic leadership has useful theoretical and practical implications. We also suggest directions for future research by providing several limitations.