• Korean Journal of Medicinal Crop Science
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• v.23 no.5
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• pp.351-356
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• 2015

Background : Ginseng is mainly grown as a break crop in paddy fields after rice has been cultured for approximately 4 - 5 years, because it reduces the negative effects of continuous rice cropping. However, physiological disorders, such as leaf discoloration, occur in ginseng grown in paddy fields with poor drainage and excessive levels of inorganic components. Methods and Results : This study investigated the effect of ridge height on the growth characteristics and yield of 6 year old Panax ginseng. Ridge height was varied by making 20, 30, and 40 cm high ridges in a pooly drained paddy field. Soil moisture content decreased, while electrical conductivity (EC) as the ridge height increased. The $NO_3$, K, Ca, Mg, and Na levels also rose as ridge height increased, but organic matter and $P_2O_4$ levels did not. The leaf discoloration ratio rose as the ridge height increased, and root yield reached a peak when the ridge height was 30 cm. Conclusion : A ridge height of 30 cm in poorly drained paddy field improved ginseng growth by reducing leaf discoloration and increasing root survival, owing to more suitable soil moisture and EC levels.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.1
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• pp.11-16
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• 2004

Oxygen is an essential element for human beings' physical and mental activities, and in particular, plays an important role in brain functions. The present study attempted to investigate the effects of supply of highly concentrated (30%) oxygen on human ability of visuospatial cognition, compared to air of normal oxygen concentration (21%). This study sampled eight male university students (the average age: 23.5) as subjects. An equipment that supplies 21% and 30% oxygen at a constant rate of 8L/min was developed. Two types of questionnaire containing 20 questions were developed to measure the ability of visuospatial cognition, and accuracy and reaction time were calculated from the result of task performance. The average accuracy was $50.63{\pm}8.63$ [%] and $62.50{\pm}9.64$[%] for 21%and 30% oxygen respectively, and a statistically significant difference was found in the accuracy between the two types of oxygen. The average reaction time was $6.60{\pm}O.77$ [sec] and $7.23{\pm}0.69$ [sec] for 21%and 30% oxygen respectively, and a statistically significant difference was not found in the reaction time. The results showed that there is no difference in the average reaction time but the average accuracy rises with the supply of highly concentrated (30%) oxygen, indicating that the supply of highly concentrated oxygen has a partially positive effect on the ability of visuospatial cognition.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.437-447
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• 2012

Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance and to increase the duration of the membrane. In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) and the organic-inorganic blended composite membranes were prepared by sol-gel casting method with loading the highly dispersed ceria and cesium-substituted tungstophosphoric acid (Cs-TPA) with cross-linking agent contents of 0.01 mL. In conclusion, CL-SPEEK/Cs-TPA/ceria (1%) membrane showed the optimum results such as 0.130 S/cm of proton conductivity at $80^{\circ}C$, 2.324 meq./g-dry-membrane of ion exchange capacity and mechanical characteristics, and 65.03 MPa of tensile strength which were better than Nafion 117 membrane.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.143-149
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• 2018

The purpose of this study is to propose a management method to maintain the pleasant indoor air quality of the dental clinic by measuring and analyzing the indoor air quality of the dental clinic. The measurement was conducted in two rooms, a lobby where many residents stay in the reception room for waiting for medical treatment, and a VIP room where treatment activities are mainly performed. Measurement items are Temperature, Humidity, $CO_2$, CO, $NO_2$, $CH_2O$, VOC, $PM_{10}$ and measurement were taken on April 27, 2018. As a result of analyzing the temperature and humidity of the dental clinic, it was analyzed that the average indoor temperature was maintained at $25^{\circ}C$ and the humidity was kept at around 50%, maintaining proper indoor temperature and humidity environment. $CO_2$ was 855ppm in the VIP Room, which satisfied the maintenance standard. In the case of the lobby, it was analyzed to be 1,160ppm, which exceeded the maintenance standard and it is judged that the carbon dioxide generated by the respiration of the people staying in the lobby is the main reason. The mean concentration of formaldehyde in the VIP room was analyzed as $436{\mu}g/m^3$, exceeding the maintenance standard, and $2,100{\mu}g/m^3$ for the VOC exceeded the recommended standard. It was analyzed that the concentration was relatively higher due to the use of disinfectant and other drugs. The mean concentration of PM-10 in the lobby was analyzed as $65{\mu}g/m^3$ and it was analyzed that it satisfied the maintenance standard. To maintain a pleasant indoor air quality in a dental clinic it is necessary to minimize the effects of formaldehyde, VOC, $CO_2$ in the VIP rooms and lobby. For this purpose, the entire ventilation system and air purification system of the dental clinic should be installed. In case of the VIP room, local exhaust ventilation should be installed and workers should wear personal protective equipment.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.1-5
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• 2021

We have investigated the electrical transport properties of polycrystalline tantalum nitride (TaN_x) films. Various compositions of tantalum (nitride) thin films have been deposited on SiO₂ substrates by reactive DC magnetron sputtering while changing the ratio of nitrogen partial pressure. The substrate temperature was maintained at 283 K during deposition. X-ray diffraction analyses indicated the presence of α-Ta and β-Ta phases in the Ta film deposited in pure argon atmosphere, while fcc-TaN_x phases appeared in the sputtering gas mixture of argon and nitrogen. The N/Ta atomic ratio in the film increased ranging from 0.36 to 1.07 for nitrogen partial pressure from 7 to 20.7%. The superconducting transition temperatures of the TaN_x thin films were measured to be greater than 3.86 K with a maximum of 5.34 K. The electrical resistivity of TaN_x thin film was in the range of 177-577 𝜇Ωcm and increased with an increase in nitrogen content. The upper critical filed at zero temperature for a TaN_0.87 thin film was estimated to exceed 11.3 T, while it showed the lowest T_c = 3.86 K among the measured superconducting TaN_x thin films. We try to explain the behavior of the increase of the residual resistivity and the upper critical field for TaN_x thin films with the nitrogen content by using the combined role of the intergrain Coulomb effect and disorder effect by grain boundaries.

• Food Science and Preservation
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• v.23 no.7
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• pp.995-1003
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• 2016

Ulmus pumila L. bark underwent distilled water extraction under three temperature condition ($4^{\circ}C$, room temperature, or $80^{\circ}C$) and two extraction times (1, or 5 min) in order to develop a functional beverage products. Changes in yield, pH, color, total phenolic (TP) content, tannin content and antioxidant activity of the aqueous extracts were evaluated for each extraction temperature and duration. Extraction conditions did not affect yield or pH value of the extracts; however CIE $b^*$ values were high in extracts prepared under high extraction temperature ($80^{\circ}C$) and long extraction duration (5 min) conditions. Both extraction temperature and duration affected the TP and tannin contents of the extracts; however, all extraction conditions resulted in ${\geq}450\;mg\;GAE/g$ TP content and ${\geq}80\;mg\;CE/g$ tannin content. All extracts exhibited ABTS and DPPH radical scavenging ability similar to that of vitamin C. Nitric oxide inhibition activity was lower in the 5 min duration sample than in the 1 min sample. The $4^{\circ}C$ extraction temperature produced an extract with the highest reducing power and hydrogen peroxide values. Extraction temperature also affected sensory evaluation results with the $80^{\circ}C$ extraction temperature producing significantly higher flavor, bitterness, and color score, than those obtained under $4^{\circ}C$ and room temperature extraction conditions.

• Information Display
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• v.23 no.4
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• pp.12-21
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• 2022

반도체 기반 양자점 (QD)소재와 CsPbX3 (X=Cl, Br, I)기반 perovskite 양자점 또는 나노결정 소재(PNC)는 매우 우수한 양자효율과 좁은 발광 선폭으로 고색재현성 디스플레이 색변환 소재 또는 발광 소재로서 각광을 받고 있다. 그러나, 기존 화학적 합성법을 통해 제조되는 QD 및 PNC 소재는 취약한 열 및 화학적 안정성으로 인해 장기 내구성의 개선이 요구된다. 이들 QD 및 PNC 소재는 모두 완전 무기 소재인 산화물 기반 유리 소재내에 생성이 가능하며, 이를 통해 장기 내구성을 근본적으로 개선할 수 있다. 반도체 기반 QD 함유 유리소재 (QDEG)의 경우, 유리 내 core/shell 구조를 가진 QD의 생성으로 양자효율의 향상이 가능했으나, 콜로이드 기반 양자점 (cQD)과 달리 다중 shell의 형성이 어려워 양자효율이 제한되고, 발광 선폭이 넓어 고색재현성 디스플레이용 색변환 소재로 적용되기에는 아직 한계가 있다. 한편, Perovskite 양자점 (또는 나노결정) 함유 유리소재 (PNEG) 소재는 QDEG과 달리 콜로이드 기반의 PNC (c-PNC)가 가지는 우수한 양자효율과 20 nm 수준의 좁은 선폭을 유리 내에서도 가지며, c-PNC 대비 열적, 화학적 및 광학적 안정성이 획기적으로 향상되어 실질적인 응용 가능성을 높이고 있다. 특히, 일반적인 용융-급랭법으로 제조하여 대량생산에 용이하고, 분말 또는 판상 등 다양한 형태로의 제작이 가능한 장점이 있다. 현재까지 제조된 PNEG의 최대 PL-QY는 450 nm 여기 시 녹색 및 적색에서 약 60% 수준이며, Al₂O₃ 분말을 이용할 경우 최대 80% 수준까지 달성이 가능하다. 또한, PNEG과 blue LED를 이용하여 백색 LED를 구현할 경우 color filter를 적용하지 않을 때, NTSC 대비 최대 약 130 % 수준의 높은 색재현 영역을 보여 주고 있으며, 실제 LCD용 BLU로 적용 시 기존 상용 c-QD 소재와 동등 이상의 색재현 영역을 보이고 있어, 실질적인 응용 가능성이 매우 높음을 확인하였다. PNEG의 상업적인 응용을 위해서는 몇 가지 추가적인 연구 개발이 필요하다. 기존 c-QD 또는 c-PNC는 나노 수준 크기의 입자가 액상에 분산된 형태로 입도 제어가 용이하나, PNEG의 경우 분말 제조 시 유리 형성 후 분쇄를 통해 제조되며, 입도가 대개 수십 ㎛ 이하로 작아질 경우 PL-QY가 저하되어, 향후 잉크젯 공정 응용을 위해서는 고효율의 분말 제조공정 개발이 필요하다. 또한, 유리 소재의 경우 절연체로서 기존 QD 소재 대비 electro-luminescence(EL) 소자의 활성층으로 사용하는데 제약이 있어 PNEG을 이용한 EL 소자 제작에 대한 연구도 필요하다. 마지막으로, 기존 c-PNC 소재와 같이 Pb가 함유되지 않은 PNEG 소재의 개발이 선결되어야 할 것으로 판단된다. 이와 같은 해결 과제들에도 불구하고, PNEG 소재는 기존 c-QD 소재 대비 매우 우수한 안정성을 기반으로 고품위 고색재현 디스플레이용 색변환 소재로서 다양한 응용에 활용될 수 있을 것으로 기대된다.

• Journal of Pharmaceutical Investigation
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• v.23 no.1
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• pp.41-49
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• 1993

The bioequivalence of two omeprazole enteric-coated products was evaluated in 16 normal male volunteers (age 26-32 yr, body weight 57-75 kg) following single oral administration. Test product was enteric-coated KD-182 tablet (Chong Kun Dang Corp., Korea) and reference product was $Rosec^{\circledR}$ capsule containing enteric-coated pellets of omeprazole (Yuhan Corp., Korea). Both products contain 20 mg of omeprazole. One tablet or capsule of the test or the reference product was administered to the volunteers, respectively, by randomized two period cross-over study ($2\;{\times}\;2$ Latin square method). Average drug concetrations at each sampling time and pharmacokinetic parameters calculated were not significantly different between two products(p>0.05); the area under the concentrationtime curve to last sampling time (8 hr) $(AUC_{0-8hr})$ $(1946.5{\pm}675.3\;vs\;2018.3{\pm}761.6\;ng{\cdot}hr/ml)$, AUC from time zero to infinite $(AUC_{o-\infty})$ $(2288.6{\pm}1212.8\;vs\;2264.9{\pm}1001.3\;ng{\cdot}hr/ml)$, maximum plasma concentration $(C_{max})$ $(772.5{\pm}283.3\;vs\;925.8{\pm}187.7\;ng/ml)$, time to maximum plasma concentration $(T_{max})$ $(2.38{\pm}1.06\;vs\;2.34{\pm}1.09\;hr)$, apparent elimination rate constant $(k_{\ell})$ $(0.5339{\pm}0.2687\;vs\;0.5769 {\pm}0.2184\;hr^{-I})$, apparent absorption rate constant $(k_a)$ $(1.1536{\pm}0.5278\;vs\;0.9739{\pm}0.9507 hr^{-1})$ and mean residence time (MRT) $(3.13{\pm}0.73\;vs \;3.41{\pm}1.04\;hr)$. The differences of mean $(AUC_{0-8hr})$, $C_{max}$, $T_{max}$ and MRT between the two products (3.69, 19.83, 1.32 and 8.99%, respectively) were less than 20%. The power $(1-{\beta})$ and treatment difference $(\triangle)$ for $AUC_{o-8hr}$ $C_{max}$ and MRT were more than 0.8 and less than 0.2, respectively. Although the power for $T_{max}$ was under 0.8, $T_{max}$ of the two products was not significantly different each other(p>0.05). These results suggest that the bioavailability of KD-182 tablet is not significantly different from that of $Rosec^{\circledR}$ capsule. Therefore, two products are bioequivalent based on the current results.

• Animal Bioscience
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• v.37 no.2
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• pp.274-283
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• 2024

Objective: The aim of the study was to evaluate the physicochemical properties (nutrient composition, pH, water content and activity, sorption properties) and mechanical properties (compression force and energy) of granulated feed mixtures with various inclusion levels of crude fibre concentrates ARBOCEL and VITACEL for broiler chickens, i.e. +0.0% (control group - group C), +0.3%, +0.8%, +1.0%, +1.2%. Methods: The feed mixtures were analyzed for their physicochemical properties (nutrient composition by near-infrared spectroscopy, pH with the use a CP-401 pH meter with an IJ-44C glass electrode, water content was determined with the drying method and activity was determined with the Aqua Lab Series 3, sorption properties was determined with the static method) and mechanical properties (compression force and energy with the use TA-HD plus texture analyzer). The Guggenheim-Anderson-de Boer (GAB) model applied in the study correctly described the sorption properties of the analyzed feed mixtures in terms of water activity. Results: The fibre concentrate type affected the specific surface area of the adsorbent and equilibrium water content in the GAB monolayer (p≤0.05) (significantly statistical). The type and dose of the fibre concentrate influenced the dimensionless C and k parameters of the GAB model related to the properties of the monolayer and multilayers, respectively (p≤0.05). They also affected the pH value of the analyzed feed mixtures (p≤0.05). In addition, crude fibre type influenced water activity (p≤0.05) as well as compression energy (J) and compression force (N) (p≤0.001) (highly significantly statistical) of the feed mixtures. Conclusion: The physicochemical analyses of feed mixtures with various inclusion levels (0.3%, 0.8%, 1.0%, 1.2%) of crude fiber concentrates ARBOCEL or VITACEL demonstrated that both crude fiber types may be used in the feed industry as a feedstuff material to produce starter type mixtures for broiler chickens.

• Environmental Engineering Research
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• v.23 no.1
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• pp.36-45
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• 2018

The phosphogypsum (PG) is a byproduct of the phosphate fertilizers manufacture. The world production estimated to 200 million tons per year induces environmental threats and storage problems, which requires strict policies to limit pollution and encourage its valorization. This paper presents a purification process of the crude PG including treatment with a diluted sulfuric acid, floatation, filtration and washing. The purified PG is used to produce plaster. The process optimization was conducted using a full factorial design. The significant factors considered in the experimental study are temperature ($X_1$), volume of sulfuric acid solution ($X_2$) and PG quantity ($X_3$). The main effects and interaction effects of these factors on the responses of the % $P_2O_5$, % F, Total Organic Carbon (TOC) ($mg{\cdot}kg^{-1}$) and pH were analyzed. The optimum conditions for $X_1$, $X_2$ and $X_3$ were found to be $60^{\circ}C$, 3 L and 1 kg, respectively and the optimized pH values was found to be 6.2. Under these conditions, 60% of $P_2O_5$, 95% of Fluorine and 98% of TOC were removed from PG. The predicted values were found approximately the same as the experimental ones. The plaster produced with purified PG was found to have similar properties to that produced from natural gypsum.