• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.106-110
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• 2006

If drugs are made from nanoparticles, their formulations can be more effective than the conventional ones. Especially, water insoluble drugs having low absorption rates into our body could show improvement in their adsorption and bioavailability by decreasing their particle sizes to nanometers. In this study, polyvinylpyrrolidone (PVP) and various sugars were employed as stabilizers for the nanoparticles of a water insoluble drug, Itraconazole. Nanoparticles were successfully produced by the wet slurry process for five days. Then, spray drying converted the aqueous dispersions into dry powders, and the redispersibility of dried nanoparticles into water was investigated. The effects of temperature, pressure, and flow rate were studied to understand the importance of processing variables on redispersibility. It was found in particle size analysis that nanoparticles containing sugars have better redispersibility than those without sugars. Additionally, the mainly spherical morphology of dried nanoparticles was identified by SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy).

• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.272-277
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• 1990

Some additives were applied to improve Yukwa(Popped rice snack) quality and process modifications were tested for cutting down soaking time and application of rice flour. Addition of soaked soybean (3%, w/w) to dough showed higher expansion rate and better physical properties with more acceptable quality by sensory evaluation of Yukwa. Baking powder, modified starch and alcoholic liquor, Mackeali(rice wine, turbid). Soju(distilled liquor) and Yakju(rice wine, clear), were no positive effect on quality of Yukwa but alcoholic liquor gave more fine texture than others. High temprature soaking $(60^{\circ}C)$ of rice for 3 hours which is near gelatinization temperature of rice starch. gave same quality of Yukwa comparing with long time soaking (12 hours) at room temperature. Extention of high temperature soaking (12 hours) did not improve the quality of Yukwa. The 100 mesh of rice flour by dry milling method was better in expansion rate and hardness than 40 and 80mesh but it was worse than ordinary wet milling. It was notified that milling method and milling mechines for Yukwa preparation should be studied in more detail.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.35-43
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• 2016

With the development of construction technology, constructions of dam and levee (dike) as well as the environmental problems are becoming issues. Recently, many countries have tried to develop and used CSG (Cemented Sand and Gravel), which needs fewer requirements than others in aggregates, constructability and ground condition during the dam construction. Mixing up with small amount of cement, CSG is able to increase the strength and proceed accelerated construction without artificial gradation adjustment of riverbed aggregate and crushed rock on construction site. Thus, CSG can minimize environmental damage resulted from quarries mining and reduce cost of construction. Unlike heat of hydration condition that regular concrete usually met, CSG exposes to repeated dry-wet and freezing and thawing environment. Thus, consider the importance of structure of dam or levee, intensive study on the durability of CSG is needed. In this study, freezing and thawing experiment was carried out to evaluate the durability of CSG. In results, the durability factor of CSG is 30~40 or >40 when the amount of cement is $0.4{\sim}0.6kN/m^3$ or $0.8{\sim}1.0kN/m^3$, respectively. The unconfined compressive strength is reduced to 30~50% or 40~70% when the amount of cement is $0.4{\sim}0.6kN/m^3$ or $0.8{\sim}1.0kN/m^3$, respectively. Taken together, the strength and durability of CSG is reliable when the amount of cement is over $0.8kN/m^3$.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.463-480
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• 2009

The weathering properties and provenance of loess-paleosol sequence deposited on gravel layer of river terrace in Bongdong-eup, Wangju-gun, Jeonbuk Province are examined using soil analysis, magnetic susceptibility measurement, grain size and element analysis. The Bongdong section consists of, from top to bottom, Layer 1(paleosol), Layer 2(loess), Layer 3(paleosol) and the gravel layer of river terrace. The magnetic susceptibility values show the systematic variations in the sequence and the results of grain size analysis reveal that the sequence was deposited by not fluvial or slope process, but eolian process, and that contains finer materials than the Daecheon loess and Chinese Loess Plateau. Among the results of soil analysis, organic contents indicate systematic variations similar to the magnetic susceptibility. The wet soil colors further reflect the characteristics of the sequence rather than the dry soil colors. Based on the analytical results of major and rare earth elements, the eolian materials contained in the sequence were deposited by the materials originated from the areas where the Chinese Loess Plateau has been originated or the reworked materials from the Chinese Loess Plateau, and after the depositions, the materials experienced the intensive chemical weathering under the humid-warm climatic conditions in the Korean Peninsula.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.157-169
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• 2009

The aim of this study was to evaluate effect of implant abutment screw coating treatment on joint stability, investigating mechanical properties of these. For this study used $ExFeel^{(R)}$ external hexed implant system and $15mm{\times}1mm$ discs. Experimental group was $1{\mu}m$ TiN, TiCN, TiC coated abutment screws and discs. To know mechanical property, i evaluated adhesion strength, surface hardness, using disc, corrosion test using screw. The results were as follows : rotation angle of coated screws increased than that of non-coated screw because of lower friction coefficient, especially TiC coated screw group had the largest value, but removal torque decreased in all coated screws (p<0.05). Torque loss before and after fatigue test was the smallest in TiC-coated screws, and the largest in non-coated screws (p<0.05), and there was no statistically significant difference between dry condition and wet condition of screws because of higher surface hardness and lower friction coefficient. From the above results, TiN, TiCN, TiC coating group had high abrasion resistance, especially TiC coated group which had low torque-consuming, high rotation angle as low friction coefficient will be considered to influence on implant abutment screw joint stability positively.

• Tuberculosis and Respiratory Diseases
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• v.53 no.2
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• pp.148-160
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• 2002

배 경 : 쥐를 고농도의 산소에 60시간 이상 노출시켰을 때 급성 폐손상이 유발되지만 내독소를 저용량으로 투여시에는 이러한 폐손상이 경감된다고 알려져 있으나 그 기전에 대하여는 확실히 밝혀지지 않고 있다. 산화질소(nitric oxide, NO)는 내독소나 염증성 사이토카인(cytokine) 등의 자극에 의해서 폐내 여러 염증세포에서 만들어지며 이 산화질소는 경우에 따라 우리 몸에 이롭거나 해로운 양면성을 지니고 있다. 저자들은 쥐에서 고농도의 산소에 의한 폐손상이 저농도의 내독소 투여로 경감되는 기전에, 산화질소가 중요한 역할을 하는지 또는 황산화효소나 다른 항염증성 사이토카인이 중요한 역할을 하는지를 규명하고자 하였다. 방 법 : 총 120마리의 쥐 (Sprague-Dawley rat)를 24마리씩 5군으로 나누어 대조군은 실내 공기를, 고농도 산소군은 100%의 산소를 100%의 산소를 60시간 투여하였고 내독소군은 100% 산소 투여시 2일간 저용량의 내독소를 투여하였다. 다른 두 군은 산화질소 합성 억제물인 aminoguanidine(AG)과 N-nitro-L-arginine methyl ester (L-NAME)를 각각 2일간 고농도 산소와 내독소에 더하여 투여하였다. 각각의 군에서 폐손상의 정도와 사망률을 관찰하고 superoxide dismutase(SOD), catalase, nitric oxide, IL-6, IL-11을 기관지폐포세척액에서 측정하고, 고농도산소 투여군의 폐조직에서 iNOS synthase rnRNA의 발현을 비교하였다. 결 과: 1. 100%의 산소에 60시간 노출시켰을 때 쥐의 사망률은 8.3% 이었고 내독소 투여군은 4.2%, NAME 투여군이 37.5%, AG 투여군이 25%로 산화질소 합성 억제제에 의하여 사망률의 증가가 관찰되었다. 2. 폐의 손상 정도를 나타내는 폐의 wet/dry 중량비와 늑막액도 100%의 산소에 노출된 군에서 증가되었고 내독소 투여에 의하여 감소되었으며 NAME나 AG 투여군에서는 오히려 증가되었다. 3. 이러한 내독소에 의한 폐손상 억제효과가 항산화효소인 SOD나 catalase, 또는 protective cytokine인 IL-6나 IL-11등의 증가와 관련이 있는지를 관찰하였으나 이들 모두에서 유의한 변화를 관찰하지 못하였다. 4. 산화질소는 100% 산소에 노출시킨 군에서도 증가하였으나 내독소 투여군에서 유의하게 더욱 증가하였고 이는 L-NAME 나 aminoguanidine의 투여시 감소하였다. 5. iNOS mRNA의 발현도 내독소 투여군에서 유의하게 증가하였다. 결 론 : 쥐의 고농소 산소 투여에 의한 폐손상은 저용량의 내독소 투여로 경감되며, 이는 주로 내독소 투여에 의한 iNOS mRNA의 발현을 유도하여 생성된 산화질소의 증가에 기인하는 것으로 생각된다.

• Tuberculosis and Respiratory Diseases
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• v.60 no.1
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• pp.49-56
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• 2006

배경 : 급성 폐손상은 폐내, 외의 원인질환들에 의해 폐포-모세혈관의 투과성이 증가하며, 폐부종에 의해 급성 저산소성 호흡곤란이 유발되는 증후군이다. 헤파린은 항응고작용 외에 자체적으로 항염증효과를 가지고 있으나, 염증성질환에 헤파린을 투여하면 출혈성 합병증이 발생하기 때문에 실제로 임상에서 이용하는데 제약이 있다. 하지만 헤파린에서 2-O와 3-O sulfate를 제거하면, 항응고 효과가 제거되고 항염증효과는 지니고 있는 비항응고성 헤파린 (nonanticoagulant heparin)으로 변화한다. 본 연구에서는 흰쥐에게 내독소 (LPS)를 투여하거나, 출혈성 쇼크를 일으켜서 유발된 급성폐손상에서 비항응고성 헤파린의 치료효과를 살펴보았다. 방법 : 각 군당 5 마리 이상의 흰쥐 (Balb/c mouse)를 이용하였다. 미정맥 (tail vein)을 통해 생리식염수 또는 비항응고성 헤파린 (50 mg/kg)을 투여한 직후에 내독소를 복강으로 투여하거나 (1 mg/kg), 심장천자를 통해 총 혈액의 1/3 정도로 제거하여 출혈성 쇼크를 유도하여 급성폐손상을 유발하였다. 내독소 투여 또는 출혈성 쇼크 유발 1 시간 후에 흰쥐를 희생시키고 폐를 적출하였고, 폐의 염증성 변화는 사이토카인 ($TNF-{\alpha}$, MIP-2, $IL-1{\beta}$)을 측정하여 살펴보았고, 폐손상의 정도는 myeloperoxidase (MPO) assay와 wet-to-dry weight ratio를 측정하여 알아보았다. 결 과 : 내독소를 투여한 흰쥐의 폐에서 대조군의 폐에 비해 사이토카인의 발현이 증가하고 ($TNF-{\alpha}$; $196.1{\pm}10.8$ vs $83.7{\pm}18.4pg/ml$, MIP-2; $3,000{\pm}725$ vs $187{\pm}26pg/ml$, $IL-1{\beta}$; $6,500{\pm}1167$ vs $266{\pm}25pg/ml$, p<0.05, respectively), 폐의 MPO 활성이 증가하였다 ($27.9{\pm}6.2$ vs $10.5{\pm}2.3U/g$ of lung protein, p<0.05). 출혈성 쇼크를 일으킨 흰쥐의 폐에서 대조군의 폐에 비해 사이토카인의 발현은 증가되지 않았으나, MPO 발현은 증가되었다 ($16.5{\pm}3.2$ vs $10.5{\pm}2.3U/g$ of lung protein, p<0.05). 내독소 투여 또는 출혈성 쇼크에 의해 급성폐손상이 유발된 흰쥐에서 생리적 식염수를 투여하거나 비항응고성 헤파린을 투여한 군 사이에 사이토카인의 발현이나 MPO 활성에 의미있는 차이는 관찰되지 않았다. 결론 : 이상의 결과로 비항응고성 헤파린은 내독소를 투여하거나 출혈성 쇼크를 일으키고 한 시간 뒤에 측정한 흰쥐의 급성폐손상에서 의미있는 치료효과를 보이지 않았다.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.315-320
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• 2015

Burcucumber (Sicyos angulatus) is an annual invasive plant species originated from North America. This species grows by twining around tree trunks, and blocks other plants from photosynthesis. Thus, it has caused the destruction of the ecosystem and biological diversity by threatening native plants. This study was performed to find out the effect of different soil water content (20%, 13%, 10%, 3%) and various shading degrees (0%, 60%, 80%) on the growth and photosynthesis-related activity of burcucumber. In the responses of burcucumber to soil water content, plant height (PH), leaf length (LL), leaf width (LW) and photosynthetic efficiency (PE) were lower at 20% water content than 10% reflecting that burcucumber plant grow well in the less dry soil and shows poor growth under wet soil condition. In shading experiment, PH, LL, LW and PE were lower at 80% than 60% shading and in general, the growth characteristics were lowered as the shading intensity increased. The improved growth of burcucumber under highly or moderately shaded condition implies that the plant can grow well without growth retardation and can be adapted to shading condition with other tall plant species including tree. Further study on the combination effects of above factors should be conducted in future for effective ecological control of burcucumber.

• Journal of Korea Water Resources Association
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• v.48 no.10
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• pp.857-868
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• 2015

Hydraulic and water quality models with high reliability are necessary for the efficient management of water quality in the reservoir. The model capacity can be demonstrated by the application for the various hydrological conditions. CE-QUAL-W2 model is laterally averaged two-dimensional hydraulic and water quality model. The W2 model, which is suitable for the narrow reservoir like the Jinyang reservoir as compared with the depth and length of waterbody, has been frequently used by many researchers. Namgang watershed is expected to increase the water demand. In this study, the W2 model is validated under two different hydrological conditions; wet year (2011) and normal year (2009). Using hydrological and water quality condition for calibration, 2011, the effect of water intake increase was simulated. The simulation results showed that the increase of water intake led to increase the concentrations in total nitrogen, total phosphorus and Chlorophyll-${\alpha}$ concentration. Especially the concentration increase was appeared during the dry season in each of up to 62.53% (Total nitrogen), 39.07% (Total phosphorus) and 232.19% (Chlorophyll-${\alpha}$). The changes of chlorophyll-${\alpha}$ is similar to those of total phosphorus concentration.

• Membrane Journal
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• v.22 no.3
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• pp.224-233
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• 2012

To improve permeation performance of gas separation membrane, polysulfone hollow fiber membrane was prepared by wet-dry phase inversion method using Triton X-100 as non-ionic additive. And variation of gas permeation behavior by additive was investigated. Various spinning conditions such as air gap, concentration of polymer, dope tank temperature were controlled and these effects were studied. The morphology and gas permeation property of hollow fiber membranes were investigated using scanning electron microscope (SEM) and bubble flow meter respectively. We confirmed that the membranes added with Triton X-100 had a smooth external skin at various air gap length conditions. The macrovoids of these hollow fiber membranes were more developed with increase of air-gap from 4 to 90 cm and that induced higher permeance. The permeance of polysulfone membranes has the higher value at comparatively lower concentration polymer (30 wt% polysulfone) and lower concentration of additive (15 wt% Triton X-100). When temperature in dope tank was controlled, the membranes prepared at $100^{\circ}C$ showed low permeance because of volatilization of additive and solvent.