• Korean Journal of Materials Research
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• v.15 no.2
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• pp.115-120
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• 2005

The aim of this research is to develop the TRIP aided high strength low carbon steels using reverse transformation process. The $4\~8\%$ Mn steel sheets were reversely transformed by slow heating to intercritical temperature region and furnace cooling to room temperature. The stability of retained austenite depends on the enrichment of carbon and manganese by diffusion during the reverse transformation. The amount of retained austenite formed after reversely transformed at $625^{\circ}C$ for 6 hrs was about $50\;vol.\%$ in the $8\%Mn$ steel. The change in volume fraction of retained austenite with a holding temperature was consistent with the changes in elongation and the strength-ductility combination. The maximum strength-ductility combination of 40,000 $MPa{\cdot}\%$ was obtained when the $8\%Mn$ steel reversely transformed at $625^{\circ}C$ for 12 hrs. However, it's property was significantly decreased at higher holding temperature of $675^{\circ}C$ resulting from the decrease of ductility.

• Membrane Journal
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• v.18 no.4
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• pp.294-305
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• 2008

This study was focused on the investigation of the effects of membrane module configuration and the temperature of feed retentate flowing along with module length on membrane performance through model simulation. A simulation model of pervaporative dehydration through membrane module assemble in which a number of unit modules are connected in parallel or in series has been established. In this study, ethanol/water mixture was used as model mixture. Some of permeation parameters in the model were quantified directly from the real dehydration pervaporation of ethanol through a lab-made membrane. By adopting the coefficients determined empirically the simulation model could be of more practical value. The simulation of pervaporation with two basic module configurations, that is, parallel connection and series connection, could present the importance of process parameters such as feed rate, module connection mode, number of stages, and inter-stage heating.

• Clean Technology
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• v.26 no.1
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• pp.79-87
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• 2020

The bio-oil produced from the fast pyrolysis of lignocellulosic biomass contains a high amount of oxygenates, causing variation in the properties of bio-oil, such as instability, high acidity, and low heating value, reducing the quality of the bio-oil. Consequently, an upgrading process should be recommended ensuring that these bio-oils are widely used as fuel sources. Catalytic fast pyrolysis has attracted a great deal of attention as a promising method for producing upgraded bio-oil from biomass feedstock. In this study, the fast pyrolysis of tulip tree was performed in a bubbling fluidized-bed reactor under different reaction temperatures, with and without catalysts, to investigate the effects of pyrolysis temperature and catalysts on product yield and bio-oil quality. The system used silica sand, ferric oxides (Fe₂O₃ and Fe₃O₄), and H-ZSM-5 as the fluidized-bed material and nitrogen as the fluidizing medium. The liquid yield reached the highest value of 49.96 wt% at 450 ℃, using Fe₂O₃ catalyst, compared to 48.45 wt% for H-ZSM-5, 47.57 wt% for Fe₃O₄ and 49.03 wt% with sand. Catalysts rejected oxygen mostly as water and produced a lower amount of CO and CO₂, but a higher amount of H₂ and hydrocarbon gases. The catalytic fast pyrolysis showed a high ratio of H₂/CO than sand as a bed material.

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.310-316
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• 2010

Nanoparticle with antimicrobial property has been applied to various fields. This study added silver/platinum nanoparticles to HEMA (2-hydroxyethylmethacrylate), NVP (N-vinyl pyrrolidone) and MMA (methylmethacrylate) in various concentrations and copolymerized by heating at $70^{\circ}C$ for 40 minutes, $80^{\circ}C$ for 40 minutes, and finally, $100^{\circ}C$ for 40 minutes. The particle size of used nano silver and platinum was 10 ~ 20 nm respectively. Using the polymer produced through the copolymerization process, the authors have produced a contact lens and measured the physical characteristics which showed water content of 34.29 ~ 39.00%, refractive index of 1.422 ~ 1.430, visible transmittance of 78.8 ~ 92.5% and tensile strength of 0.149 ~ 0.179 kgf. The ophthalmic lens material produced using silver/platinum nanoparticles satisfied the basic physical properties required for contact lens application.

• Journal of Hydrogen and New Energy
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• v.19 no.6
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• pp.514-519
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• 2008

In the present study, biomass pyrolysis was done using five different kinds of catalysts with change in the support species and their compositions. Ni was loaded on alumina, ceria and alumina-ceria supports using co-precipitation method. In all the catalysts, 30wt% of nickel was loaded on the support materials. The paper used in daily writing purposes was taken into account as biomass sample. In the experiment, 19 of biomass was mixed with o.1g of each catalyst separately. Thermogravimetric analysis (TGA) was performed with all the catalysts diminished the initial degradation temperature of paper biomass sample considerably. During the pyrolysis process, the temperature was raised from room temperature to $800^{\circ}C$ with the heating rate of $10^{\circ}C$/min in the furnace. The cumulative $H_2$ volume had reached the best value of l4.02ml with the Ni/$Al_2O_3-CeO_2$ 30wt%/(50wt%-50wt%) catalysts. In presence of all the catalysts, the highest amount of $H_2$ was produced at $800^{\circ}C$, 10min. of residence time.

• Physical Therapy Korea
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• v.3 no.2
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• pp.19-28
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• 1996

The purpose of this study was to asses and compare the effects of superficial heating on the pain threshold at limbs in healthy adult and adult hemiplegia. We used hot pack for superficial heat and applied to healthy adult(n=12) and adult hemiplegia(n=12) on lumbar region. Pain treshold was quantatively measured by an electrical stimulator and measured before hot pack application, immediatly and post 30 minutes after hot pack application on the distal parts of limbs(styloid process of radius, medial malleoulus of tibia). The results were as follows 1) A statically significant defference in pain treshold were not found at limbs of healthy adult and adult hemiplegia that have an affected side and a non-affected side before hot pack application, immediatly and post 30 minutes after hot pack apllication(p>0.05). 2) In comparance of pain threshold of upper and lower limbs in the all subjects, pain threshold was significantly increase at lower limbs(p<0.01). 3) In comparance of pain threshold of limbs between healthy adult and adult hemiplegia, pain threshold was showed a significant defferance at the upper and lower limbs of affected side before hot pack application(p<0.05, p<0.01).

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.985-997
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• 2016

The objectives of this study, which filled gaps in previous studies, were: (1) to find the optimal mixing condition of nanoemulsions containing oleoresin capsicum (OC), Tween 80, propylene glycol (PG), and sucrose monostearate (SES) by microfluidization; (2) to investigate their properties and stability depending on such factors as pH, temperature, and heating time; (3) to measure the effect of adding ascorbic acid. In order to test these objectives, the following three experiments were conducted: Firstly, in order to find the optimal mixing ratio, nanoemulsions containing OC - the mean diameter of which is smaller than 100 nm - were prepared through the process of microfluidization; and their mean particle size, zeta potential, and capsaicinoids were measured. The test results indicated that the mixing ratio at OC : Tween 80 : PG + water(1:2) = 1 : 0.2 : 5 was optimal. Secondly, the properties and stability of nanoemulsions were investigated with varying parameters. The test results illustrated that single-layer nanoemulsions and double-layer nanoemulsions coated with alginate were stable, irrespective of all the parameters other than/except for pH 3. Thirdly, the properties of nanoemulsions were then analyzed according to the addition of ascorbic acid. The results demonstrated that the properties of single-layer nanoemulsions were not affected by addition of ascorbic acid. In case of alginate double-layer nanoemulsions, the particle size was reduced, and zeta potential increased with the addition of ascorbic acid. In conclusion, the demonstrated stability of various nanoemulsions under the different conditions in the present study suggests that these findings may constitute a basis in manufacturing various food-grade products which use nanoemulsions-and indicate that food nanoemulsions, if adopted in the food industry, have the potential to satisfy both the functionality and acceptability requirements necessary to produce commercially marketable food-grade products.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.84-92
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• 2010

현재 가동 중인 몇몇 가압 경수로 원전 안전 1등급 설비의 이종금속 용접부는 일차수응력부식균열(PWSCC : Primary Stress Corrosion Cracking) 발생의 세가지 조건(민감 재질, 부식 환경, 인장응력)을 동시에 충족하고 있다. 즉, 이종금속 용접부는 PWSCC에 민감한 재질인 Alloy 600 계열 합금으로 제작 또는 용접되어 있으며 고온 수화학 부식 환경 하에 놓여있다. 아울러 오스테나이트 스테인리스 강의 예민화 예방을 위한 용접 후열처리 미실시로 높은 인장 용접 잔류응력이 작용하고 있다. 이러한 이종금속 용접부의 특성상 PWSCC가 발생할 잠재성이 있을 뿐만 아니라 국내외적으로 Alloy 600 계열 합금으로 제작 및 용접된 가압 경수로 원전 안전 1등급 설비의 이종금속 용접부에 실제 PWSCC가 발생된 사례들이 다수 보고되고 있다. 운전 환경 및 재질 변화 없이 PWSCC 발생을 예방하기 위해서는 인장 잔류응력을 이완시켜 낮은 인장 또는 압축 응력화하여야 한다. 이러한 인장 잔류응력 이완방법들로는 PWOL(Pre-emptive Weld Overlay), 레이저 피닝(Laser Peening), MSIP(Mechanical Stress Improvement Process), 워터 제트 피닝(Water Jet Peening), IHSI(Induction Heating Stress Improvement) 방법들이 있는데 공정 시간이 짧고 열 에너지 원이 필요 없으며 전체적인 소성 변형을 야기시키지 않는 레이저 피닝을 본 연구의 대상 방법으로 한다. 본 연구에서는 동적 유한요소 해석을 통해 용접 잔류응력을 이완시키는 레이저 피닝의 효과를 검증하고 용접 잔류응력에 미치는 레이저 피닝 변수의 영향을 고찰하고자 한다. 내부 보수용접이 수행된 경수로 원전 가압기 노즐 이종금속 용접부에 레이저 피닝을 적용한 경우에 대해 상용 유한요소 해석 프로그램인 ABAQUS를 이용하여 동적 유한요소해석을 수행한 결과, 고온 수화학 일차수와 접하는 Alloy 600 계열 합금 내면에서의 인장 잔류응력이 상당히 이완됨을 확인하였다. 또한, 최대충격 압력이 증가할수록, 충격압력 지속시간이 증가할수록, 레이저 스팟 직경이 증가할수록 내표면 인장 잔류응력 이완 정도는 감소하나 이완되는 영역의 깊이는 증가함을 알 수 있다. 또한, 레이저 피닝 방향이 잔류응력 이완에 미치는 영향은 미미함을 알 수 있다.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.53.1-53.1
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• 2018

During a major solar eruption, the erupting plasma is possibly out of the equilibrium ionization state because of its rapid heating or cooling. The non-equilibrium ionization process is important in a rapidly evolving system where the thermodynamical time scale is shorter than the ionization or recombination time scales. We investigate the effects of non-equilibrium ionization on EUV and X-ray observations by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory and X-ray Telescope (XRT) on board Hinode. For the investigation, first, we find the emissivities for all the lines of ions of elements using CHIANTI 8.07, and then we find the temperature responses multiplying the emissivities by the effective area for each AIA and XRT passband. Second, we obtain the ion fractions using a time-dependent ionization model (Shen et al. 2015), which uses an eigenvalue method, for all the lines of ion, as a function of temperature, and a characteristic time scale, $n_et$, where $n_e$ and t are density and time, respectively. Lastly, the ion fractions are multiplied to the temperature response for each passband, which results in a 2D grid for each combination of temperature and the characteristic time scale. This is the set of passband responses for plasma that is rapidly ionized in a current sheet or a shock. We investigate an observed event which has a relatively large uncertainty in an analysis using a differential emission measure method assuming equilibrium ionization state. We verify whether the observed coronal plasmas are in non-equilibrium or equilibrium ionization state using the passband responses.

• Journal of architectural history
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• v.21 no.1
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• pp.83-98
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• 2012

The starting point of this study is the concerning of simple behavioral pattern that whoever enters the inner space with taking off his shoes should go out from the position where he laid his shoes. The using of Ondol (floor heating room) and Maru (lifted wood floor) had changed the architectural space from chair-sitting to floor-sitting space, and it also made the behavior of taking off the shoes at the entrance of building and stepping on the lifted floor. This simple behavior has possibility to make lots of changes to the culture of architectural design. With this noticeable point, this paper is talking about the cultural feature of Korean traditional architecture, especially about the influence of tanking off and putting on shoes. The matter of shoes has changed diverse aspects of building and layout planning. It maximized the difference between front and rear part of building and characterized the lateral extension of Korean traditional house. The ritual space also had evolved from chair-sitting to floor-sitting space according to the type of ritual behavioral pattern. The change on the single building level had influenced on the layout planning of architectural complex. For examples, the parallel layout of ChangDeok-gung palace and the long sequential process to the main pavilion of Buddhist temple are the result of the matter of shoes. And NuGak(樓閣), the double-storied pavilion, on the axis of entering sequence's node is one of the unique planning elements that makes possible to go through the building without taking off the shoes and also makes upper level space for staying. In short, Korean traditional architecture that has the chair-sitting spatial origin of the East Asian cultural sphere has pursued new architectural issues and planning methods according to evolution to the floor-sitting culture.