• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.23-32
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• 2022

This paper performs two-dimensional numerical simulation of surface water-groundwater coupled flow and solute transport to investigate the effect of the hyporheic exchange at the sediment-water interface (SWI) on surface solute transport. For the impermeable bed case in the absence of hyporheic flow, the trapping effect of flow recirculation associated with the ripple bed controls the shape of breakthrough curves (BTCs). However, the permeable bed case with hyporheic flow stimulates the extended tailing of the BTCs more significantly due to the elevated concentration of the BTC tailing resulting from slow hyporheic velocity. Also, the increased bottom pressure at the SWI with an increase in surface velocity shortens the BTC tailing because of increasing hyporheic velocity. These results infer that hyporhiec flow is critically important in predicting solute residence times in surface water.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.361-369
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• 2015

A general linear mixed-effects model is often used to analyze repeated measurement experiment data of a continuous response variable. However, a general linear mixed-effects model can give improper analysis results when simultaneously detecting heteroscedasticity and the non-normality of population distribution. To achieve a more robust estimation, we used a heavy-tailed linear mixed-effects model for a more exact and reliable analysis conclusion than a general linear mixed-effects model. We also provide reliability analysis results for further research.

• Communications for Statistical Applications and Methods
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• v.3 no.3
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• pp.83-92
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• 1996

확률화 블록 계획법에서 우산형 대립가설에 대한 점근 분포 무관 검정법을 제시하고 제안된 검정통계량의 점근적 정규성과 모수적 방법 및 비모수적 방법의 점근상대효율을 관찰하였다. 검점통계량은 블록 효과를 추정하여 제거한 관측치의 전체 블록 순위를 사용하여 제안하였으며 제안된 검정통계량의 소표본 Monte Carlo 연구를 통해 실험 검정력을 비교하였다. 그 결과 본 논문에서 제안된 검정통계량이 꼬리가 두꺼운 분포에서는 전반적으로 우수하고 로버스트한 것으로 나타났다.

• Korean Journal of Plant Resources
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• v.34 no.4
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• pp.270-277
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• 2021

Veronica rotunda var. subintegra (Nakai) T. Yamaz. is perennial herb belonging to the family Scrophulariaceae, native to Korea. Plant growth regulators, cutting mediums, cutting position, and leaf size were examined to investigate the requirements for cutting propagation of V. rotunda var. subintegra. This study was conducted over a period of 6 weeks from March to May 2017 in the Division of Plant Resources, Korea National Arboretum. For all treatments, survival and rooting percentage was 100%. In PGRs experiment, the number of roots and shoot length treated with 100 mg/L IBA treatment was significantly higher than that of NAA treatment. The shooting percentage was decreased with an increase of the PGRs concentration. In growing substrates experiment, the number of roots on commercial soil (61.2) was the highest, followed commercial + kanuma soil (45.7), and the lowest was kanuma soil (41.8). The shoot length treated with commercial soil (8.9 cm) was significantly greater than that of kanuma soil (4.1 cm). In cutting positions experiment, the number of roots treated with apical (56.6) was significantly higher than that of basal (38.8). In leaf-cut experiment, the number of roots and of shoot length treated with full leaf was significantly higher than that of half leaf. As a result, we recommend treating cuttings with 100 mg/L IBA treatment, commercial soil, apical position, and full leaf for successful cutting propagation of V. rotunda var. subintegra.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.379-386
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• 2015

The solubilization of p-chlorobenzoic acid in aqueous solutions of pure cationic, nonionic, amphoteric, and their mixed surfactant systems have been measured by the UV-Vis spectrophotometric method. The effects of hydrophobic tail-group with different chain length and the hydrophilic head-group on the solubilization of p-chlorobenzoic acid have been studied and also thermodynamic parameters have been calculated from the dependence of K_s values on the temperature. The results show that the values of ΔG^o for the solubilization by all surfactant systems are negative and the values of ΔH^o and ΔS^o are all positive.

• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.987-998
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• 2013

This paper considers the statistical characteristics on the air quality (PM10) of Korea collected hourly in 2011. PM10 in Korea exhibits very strong correlations even for higher lags, namely, long range dependence. It is power-law tailed in marginal distribution, and generalized Pareto distribution successfully captures the thicker tail than log-normal distribution. However, slowly decaying autocorrelations may confuse practitioners since a non-stationary model (such as changes in mean) can produce spurious long term correlations for finite samples. We conduct a statistical testing procedure to distinguish two models and argue that the high persistency can be explained by non-stationary changes in mean model rather than long range dependent time series models.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.7
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• pp.1035-1040
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• 2015

4-Hexylresorcinol (4-HR) has been used for prevention of melanosis in shrimp. Recently, 4-HR in EU and other countries was authorized with maximum residue levels of 1~2 mg/kg but remains unauthorized in Korea. Therefore, the aim of this study was to investigate the effect of 4-HR on melanosis inhibition and residual levels in Korean shrimp according to various concentrations and soaking times. We previously reported that the HPLC-FLD method can be used for detection of 4-HR at maximum levels of 1~2 mg/kg in shrimp. Our results show that residual levels of 4-HR in peeled and unpeeled shrimps were in the range of 0.86 to 13.46 mg/kg and 0.02 to 2.33 mg/kg, respectively. In addition, 4-HR treatment at concentrations of 10 and 20 mg/L for 72 h were effective for inhibition of melanosis in peeled shrimp compared with unpeeled shrimp. These results provide basic data for the establishment of guidelines and regulation related to 4-HR.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.899-904
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• 2007

During the conceptual design phase of fighter class aircraft, the high speed wind tunnel test with 1/20 scale wing-body-tail model has been conducted to investigate the effects of leading edge flap deflection on the supersonic cruise performance of the aircraft. To select the proper leading edge flap deflection for the wind tunnel test, the aerodynamic characteristics due to various leading edge flap deflections have been analyzed by using corrected supersonic panel method. Based on the results obtained from the experimental and numerical approaches, the effects of leading edge flap deflection have shown to be useful to enhance the supersonic cruise performance of fighter class aircraft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.575-580
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• 2007

During the conceptual design phase of a canard type high maneuverable aircraft, the low speed small scale wind tunnel test was conducted to investigate the high angle-of-attack static stability of the aircraft. In this study, 1/50th scale generic canard-body-wing model was used for the small scale wind tunnel test. For the analysis of static stability including high angle-of-attack nonlinear characteristics, the vertical tail effects were studied due to canard deflections. In addition, the nose chine effects were studied at high angle-of-attack. Based on the results obtained from the experimental study, the configuration change effects for canard type aircraft on high angle-of-attack static stability have been able to analyze.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.167-174
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• 2021

Computational Fluid Dynamics (CFD) was performed under low-speed wind tunnel test conditions using a 29.7% scale model of the NASA common research model. A wind tunnel test was conducted to measure the aerodynamic coefficient of the CRM with Belly sting model support configuration at a low Reynolds number of 0.3×106 and it was compared with the aerodynamic coefficient of CFD analysis. In order to verify the validation of the analysis, a computational analysis under the conditions of the advance research was performed and compared. The interference effect of the Belly sting model support affected not only the fuselage but also the main and tail wings.