• Journal of Korea Water Resources Association
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• v.37 no.4
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• pp.341-352
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• 2004

In this study(II), the model developed in the previous study(I) has been tested on two cases of constant-slope areas to verify the model applicability. Firstly, an impervious one-dimensional runoff problem has been simulated. Secondly, an impervious two-dimensional runoff problem at a converging plain which consists of a V-shaped section plus a portion of the surface of a cone has been simulated. For each case, the simulation results have good agreements with the observed data. And the model has been applied to actual watersheds, which were the Sulma watershed with 8$\textrm{km}^2$ and the Donggok watershed with 33.2$\textrm{km}^2$, drainage area, respectively. The simulated results agree with observed in terms of discharges at several stations. Monte Carlo simulation was also performed on the same watersheds and the modeling results have been evaluated. The suggested model can be used for real-time forecasting of rainfall-runoff analysis, and will contribute for basinwide flood control in the future.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.545-550
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• 2010

Freeman-Sheldon Syndrome (FSS, also known as "Whistling Face Syndrome") is a rare genetic condition which characteristically includes a small "whistling" mouth, a flat mask-like face, club feet, joint contractures usually involving the fingers and hands, and under-development of the cartilage of the nose. Intelligence is usually normal. Most of the features of this syndrome are due to muscle weakness. The patient, 11 years old boy was consulted from pediatrics to pediatric dentistry due to dental management. After clinical & radiographic examinations, severe multiple problems were found. Dental problems were microsomia(whistling mouth) & micrognathia, perioral muscle contracture, restricted mouth opening, poor oral hygiene & care, generalized dental caries, high palatal vault, severe malocclusion & crowding. And Orthopedic problems, ophthalmic & respiratory, anesthetic problems were found. Then He also had psychiatric problem, hospital(dental) phobia due to previous medical history(frequent hospitalization). And he had genital problem, cryptochidism, too. Due to these intricate problems, he suffered with feeding, swallowing difficulties and showed growth retardation. For enhancing patient's oral health, pediatric dentist, orthodontist, oral surgeon, pediatrician, psychiatrist, orthopedist, they all agree with early, cautious intervention and treatment. So, he has been treated by multidisciplinary care, now he is recovering general health maintenance.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.248-262
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• 2016

The study documents the analysis on characters and symbols shown in the pavement markings in the perspective of mathematics educators. The purpose of this study is to propose a pavement marking method that can enhance readability from the driver's eye position. To this end, this study analyzed the figure of the pavement markings that can be actually recognized by the projective geometry perspective. As a result, it proposed alternatives to the current pavement markings by introducing the concept of the compression ratio. Results of the study are as follows. First, the rule was established to obtain the compression ratio. If the observation of two viewing angles are x and y, then the compression ratio S is ${\sin}y/{\cos}\(\frac{x-y}{2}\)$. Second, we presented two alternatives to the pavement marking method for the displayed information. One is a method for improving the pavement markings in terms of the compression ratio, the other is a method by varying vertical length of the pavement markings while holding its width constant. Based on the outcomes from this study, a mathematical analysis can be further studied for the perception of speed according to the types of pavement marking line.

• Applied Biological Chemistry
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• v.30 no.3
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• pp.242-249
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• 1987

Physicochemical properties on heat-moisture treatment of sweet potato starch were investigated. Starch granules of sweet potato observed by photomicroscope, polarized-light microscope and scanning electron microscope were round and polygonal. X-ray diffraction pattern was changed from Ca-pattern to A-pattern upon heat-moisture treatment. Water binding capacity was drastically increased as the moisture level was increased. The swelling power and solubility at the same temperature were decreased by heat-moisture treatment. Transmittance of 0.1% starch suspensions was increased rapidly from $65^{\circ}C$ in case of untreated starch and from $70^{\circ}C$ in case of treated starch. The starch on heat-moisture treatment was gelatinized over higher temperature range than the untreated starch.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.4
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• pp.297-302
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• 1999

Cotyledonary abnormalities were observed in secondary somatic embryos which were developed from calli cultured on MS medium with various concentrations of 2,4-D. In MS medium containing hormone-free or $0.1mg/{\ell}$ 2,4-D, the frequency of normal embryo formation with two cotyledons were above 57%. According to concentration of 2,4-D increment the frequency of normal embryos were decreased. In MS medium containing $4mg/{\ell}$ 2,4-D, the frequency of normal embryo formation was just 10%. The rate of germination was as follows; 37.7% of somatic embryos had one cotyledon, 85% two cotyledons, 38% three cotyledons, 35% four cotyledons, 25% five cotyledons and 29% trumpet-like cotyledons. About 80% of the embryos with two cotyledons were converted into normal plants, but one, three or four cotyledons were only 6.8~10%. The five or trumpet-like embryos were not developed into normal plants.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.506-511
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• 2006

ZnO nanorods were prepared by the hydrothermal reaction of a solution containing $Zn(NO_3)_2{\cdot}6H_2O$, NaOH, cyclohexylamine, ethanol and water, and their $NO_2$ and CO sensing behaviors were investigated. By the control of water concentration in solution, the morphology and agglomeration of ZnO nanorods could be manipulated, which is associated with the variation of $[OH^-]$ resulted from an interaction between water and cyclohexylamine. Sea-urchin-like and well-dispersed ZnO nanorods were prepared at low and high water content, respectively. Well-dispersed ZnO nanorods showed 1.8 fold change in resistance at 1 ppm $NO_2$ while there was no significant change in resistance at 50 ppm CO. This selective detection of $NO_2$ in the presence of CO can be used in automated car ventilation systems.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.603-608
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• 2005

The molded macroporous poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) rods produced by a facile molding process were polymerized in situ within a tubular mold, chromatographic column ($4.6{\times}100mm$) by free radical polymerization. It was complemented by epoxy derivatized monolithic column and chemical modification of the epoxide groups with the sulphuric acid. By variation of the polymerization conditions, such as the ratio of the monomers, the porogen (pore generating material), and the temperature, the pore size could be varied, so the retention time of the samples may be adjusted. For the mixture of caffeine and tryptophan in the prepared monolithic column, the influences of polymerization material compositions to the efficiency, selectivity, and resolution of the monolithic column were investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1199-1205
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• 2006

This paper proposes a wideband monopole antenna with improved band rejection characteristics by inserting two band notch slots with half wavelength in radiator. The designed antenna is composed of bow-tie patch fed electromagnetically with parasitic ground patch of a semicircular shape. We obtained band rejection filter-like characteristics by controlling coupling amounts between two horizontal resonance slots. Using this technique, we achieved the broad rejection bandwidth and improved skirt characteristics compared with only one notch slot. The measured bandwidth is from 2.7 GHz to 6.9 GHz for VSWR below 2.0 except the limited band of $4.96{\sim}5.51GHz$. This antenna shows a similar radiation pattern of the ideal monopole and the radiation gain reduction is more than $5{\sim}10dB$ on the x-z plane at rejection frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.510-515
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• 2011

In this paper, an artificial transmission line coupler with slotted-triangular patches, which is compact and spacesaving structure, is proposed. The proposed structure has specific features of not only convenience for adjusting the characteristic impedance and the phase of its coupled line by varying the lengths of the slots of the artificial transmission lines in designing a coupler but also the maximized coupling value at less than ${\lambda}$/4 electrical length so that it can be designed in compact and small dimensions, while conventional coupled line couplers are generally limited in compact and miniaturized designs by their ${\lambda}$/4 transmission lines. A fabricated 15 dB test-coupler at 2.4 GHz band by proposed design method shows good agreement with theory and simulation.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.299-299
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• 2014

기존의 고출력 광원들이 환경문제 등으로 외국에서 규제대상으로 지정되고 있는 가운데고체 상태의 광원인 Light-emitting diode (LED)는 기존의 광원에 비해 에너지 절감효과 크기 때문에 인해 널리 사용되고 있는 추세이다. 대부분의 백색 LED의 경우 청색 LED에 황색 형광체를 사용하는 것이 일반적이다. 그러나 이의 경우 빛의 흡수와 재방출 과정에서 생기는 에너지 변환손실의 문제가 불가피하다. 또한, 두 종류의 색을 섞어서 나타나는 낮은 연색성의 문제가 있고 사용할 수 있는 형광체의 종류와 조합도 일본 등 해외에 출원된 특허권으로 연구개발에 어려움이 있다. 이를 해결하기 위해 본 연구에서는 형광체를 사용하지 않는 단일 백색 LED를 개발을 위하여 극성과 반극성을 조합한 구조를 연구하였다. Photo-lithography를 이용하여 다양한 크기와 구조의 홀 패턴을 얻을 수 있었으며, metal organic chemical vapor deposition을 이용하여 다양한 형태의 피라미드 구조를 성장할 수 있었다. 패턴의 홀 크기와 홀 사이의 간격을 조절하면서 성장을 진행 하였고, 그 결과 pyramid와 truncated pyramid 모양의 GaN 구조를 성장할 수 있었다. [그림 1] Pyramid 구조의 반극성 면과 truncated pyramid 구조의 극성 면사이의 성장속도 차이 때문에 양자우물의 두께가 달라짐을 확인하였다. 이로 인해 양자구속효과가 달라져 다른 파장의 발광을 기대할 수 있었다. 뿐만 아니라 In의 확산거리가 Ga보다 길어서 홀사이 간격을 달리하면 In조성비가 달라지는 효과가 있음을 확인하였고 다양한 홀 사이 간격으로부터 각기 다른 파장의 발광을 얻을 수 있었다. 파장을 조금 더 상세하게 분석하기 위하여 Photoluminescence과 Cathodoluminescence을 사용하였다. 이로써 여러 파장을 발광하는 패턴을 섞어 넓은 영역의 발광 스펙트럼을 만들었다. 특히 패턴을 섞는 방법도 홀과 에피 구조를 섞는 방법, 크기가 다른 홀 패턴을 배열하는 방법등 다양히 하며 가장 좋을 패턴을 연구하였다. 그리하여 최적의 패턴과 구조, 성장조건을 찾아 백색의 CIE 좌표값을 얻을 수 있었다.