Novel method for investigation of a K-Mg-based CO₂ sorbent for sorption-enhanced water-gas shift reaction

Byun, C.K.,Kwon, S.J.,Im, H.B.,Ahn, H.S.,Ryu, H.J.,Yi, K.B. Pergamon Press 2016 RENEWABLE ENERGY Vol.87 No.1

CO<SUB>2</SUB> sorption reactions at 20 bar and two different temperatures (i.e., 180 and 220 <SUP>o</SUP>C) using a K-Mg-based CO<SUB>2</SUB> sorbent were carried out in a custom-designed high-pressure thermogravimetric analyzer (pressurized bubbling fluidized bed reactor on a scale) coupled with a gas chromatograph. The experimental apparatus, including the thermogravimetric analyzer, was custom-designed to measure weight changes caused by either CO<SUB>2</SUB> sorption or water sorption or both. Analysis of the CO<SUB>2</SUB> sorption reaction revealed that water sorption takes place rapidly with a moderate CO<SUB>2</SUB> sorption rate at the early stage of the reaction. Then, the reaction migrates to CO<SUB>2</SUB> sorption with simultaneous water desorption. Therefore, the mechanism of the CO<SUB>2</SUB> sorption reaction is assumed to consist of fast hydration of K<SUB>2</SUB>CO<SUB>3</SUB> and MgO, formation and decomposition of KHCO<SUB>3</SUB>, and finally carbonation of Mg(OH)<SUB>2</SUB> resulting in MgCO<SUB>3</SUB> as the main product. K<SUB>2</SUB>CO<SUB>3</SUB> is assumed to provide an efficient pathway for CO<SUB>2</SUB> and water to travel into the core region of the sorbent via a reversible reaction between K<SUB>2</SUB>CO<SUB>3</SUB> and KHCO<SUB>3</SUB>.

PET 영상의 잡음개선을 위한 적응적 공간 필터 개발

우상근,최용,임기천,송태용,정진호,이경한,김상은,최연성,박장춘,김병태,Woo, S. K.,Choi, Y.,Im, K. C.,Song, T. Y.,Jung, J. H.,Lee, K. H.,Kim, S. E.,Choe, Y. S.,Park, C. C.,Kim, B. T. 대한의용생체공학회 2002 의공학회지 Vol.23 No.3

양전자방출단층촬영기(Positron emission tomography, PET) 영상 개선을 위하여 적응적 공간 필터를 개발하였으며. 개발한 필터의 성능을 시뮬레이션데이터. 모형 PET 영상과 환자 PET 영상을 이용하여 평가하였다. 경계화소로 검출된 화소와 윈도우내의 모든 화소값이 동일한 화소는 보존하고. 그 외 화소에 대하여 2:7:2 비율로 가중치를 주어 정열한 후 중앙의 9개 화소에 대한 평균값으로 대치하였다. 경계화소를 검출하기 위하여 두 개의 임계값(TH7, TH2)을 이용하였으며. 다음의 조건을 만족하면 경계화소로 판단하였다 . THl ($pix_max{\times}0.1/log_2(NPM)$, NPM :주변값중 최상위 값과 최하위 값을 제외한 주변값들의 평균) 보다 작은 ADs (중앙값과 주변값의 차에 대한 절대값) 개수는 8-k이고. TH2 ($NPM{\times}0.1$) 보다 큰 ADs 개수는 k. 여기서 k는 2, 3 ‥‥ 6의 값을 가진다 성능평가 결과 이 연구에서 제안한 필터가 가우시안 필터, 가중메디안 필터, 부분집합평균메디안 필터 등과 비교하여 우수한 성능을 제공하는 것을 관찰하였다. 본 논문에서 개발한 간단한 적응적 공간 필터는 공간 분해능 저하는 최소화하면서 균일도와 대조도를 향상시키는데 효과적 이여서 정확한 PET 영상 해석에 기여할 것으로 기대된다 A spatially adaptive falter was formulated to imrove PET image qualify and the Performance of the filter was evaluated using simulation and phantom and human PET studies. In the proposed filter. if a pixel was identified as the edge Pixel, the Pixel value was Preserved. Otherwise a Pixel was replaced by the mean of the pixel values weighted by 2:7: 2. A Pixel was identified as the edge Pixel. if it satisfies the following conditions : the number of ADs (absolute difference between center and neighborhood pixels) which is smaller than THl (($pix_max{\times}0.1/log_2(NPM)$, NPM : mean of 6 neighborhood pixels excluding minimum and maximum) is 8-k and the number of ADs which is lager than TH2 ($NPM{\times}0.1$) is k. where k : 2, 3, …, 6. The results of this study demonstrate the superior performance of the Proposed titter compared to Gaussian fitter, weight median filter and subset averaged median filter. The proposed tittering method is simple but effective in increasing uniformity and contrast with minimal degradation of spatial resolution of PET images and thus. is expected to Provide improved diagnositc quality PET images .

Analysis of $Si_3N_4$ Ultra Fine Powder Using High-pressure Acid Digestion and Slurry Injection in Inductively Coupled Plasma Atomic Emission Spectrometry

김K.H.,김H.Y.,임H.B.,Kim, K.H.,Kim, H.Y.,Im, H.B. Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.2

Si3N4 powder has been analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sample was dissolved by high-pressure acid digestion with HF, H2SO4 (1+1), and HNO3 mix ture. This technique is well suited for the impurity analysis of Si3N4 because the matrix interference is eliminated. A round-robin samples trace elements, such as Ca, W, Co, Al, Fe, Mg, and Na, were determined. For the direct analysis, slurry nebulization of 0.96 mm Si3N4 powder also has been studied by ICP-AES. Emission intensities of Fe were measured as ICP operational conditions were changed. Significant signal difference between slurry particles and aqueous solution was observed in the present experiment. Analytical results of slurry injection and high-pressure acid digestion were compared. For the use of aqueous standard solution for calibration, k-factor was determined to be 1.71 for further application.

BREAKUP MODELING OF A LIQUID JET IN CROSS FLOW

K.-S. IM,K.-C. LIN,M.-C. LAI,M. S. CHON 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.4

We propose a novel breakup model to simulate the catastrophic breakup regime in a supersonic cross flow. A developed model has been extended from an existing Kelvin-Helmholtz/Rayleigh-Taylor (K-H/R-T) hybrid model. A new mass reduction rate equation, which has critical effects on overall spray structure, is successfully adopted, and the breakup length, which is an important parameter in existing model, is replaced by the breakup initiation time. Measured data from the supersonic wind tunnel with a dimension of 762×152×127 mm was employed to validate the newly developed breakup model. A nonaerated injector with an orifice diameter of 0.5 mm is used to inject water into a supersonic flow prescribed by the momentum flux ratio of the liquid jet to free stream air, q0. The conservation-element and solution-element (CE/SE) method, a novel numerical framework for the general conservation law, is applied to simulate the supersonic compressible flow. The spray penetration height and average droplet size along with a spray penetration axis are quantitatively compared with data. The shock train flow structures induced by the presence of a liquid jet are further discussed.

Comparison study on neutronic analysis of the K-DEMO water cooled ceramic breeder blanket using MCNP and ATTILA

Park, J.S.,Kwon, S.,Im, K. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

A comparison study of main parameter calculations: neutron wall loading (NWL), tritium breeding ratio (TBR), and nuclear heating, on a Korean fusion demonstration reactor (K-DEMO) neutronic analysis model using MCNP and ATTILA was performed to investigate the feasibility of using ATTILA for the main parameter calculations. The model was created by commercial CAD program (Pro-Engineer(TM)) as a 22.5<SUP>o</SUP> sector of tokamak consisting of major components such as blankets, shields, divertors, vacuum vessels (VV), toroidal field (TF) coils, and others, which was directly imported into ATTILA by Parasolid file. The discretizing in space, angle, and energy variables were refined for application of the K-DEMO neutronic analysis model through an iterative process since these variables greatly impact on accuracy, solution times, and memory consumptions in ATTILA. The main parameter calculations using ATTILA and the result of comparison studies indicate that the NWL distributions by two codes were almost agreed within discrepancy of 3.3%; the TBR distribution using ATTILA was slightly bigger than MCNP with a difference 3.9%; the nuclear heating values on TF coils and VV were bigger than MCNP with relatively high difference (17% and 28%). As a result of comparisons, ATTILA shows close agreement with MCNP within reasonable discrepancy ranges (3.3-28%).

2단계 급속동결 및 초자화 동결한 토끼상실배의 체외생존성에 관한 연구

정구민,이창규,임경순,김수헌 서울대학교농과대학농업개발연구소 1990 서울대농학연구지 Vol.15 No.1

본 시험은 수정란 급속동결보존기술의 개발을 위한 기초자료를 얻기 위하여 2단계 급속동결 및 초자화동결이 토끼 상실배의 체외발생등에 미치는 영향을 검토하고자 실시하였으며, 얻어진 결과는 다음과 같다. 1. 토끼 상실배를 1.5, 2.0, 2.5 및 3.0 M glycerol과 0.5 M sucrose가 포함된 동결액에 실온에서 10분간 노출후 -30℃에서 30∼40분간 정치하여 급속동결하였을 때 발생율은 각각 36.4, 83.3, 92.3 및 84.2%로 2.5 M glycerol에서 가장 높았다. 2. 토끼 상실배를 1.5, 2.0, 2.5 및 3.0 M 1,2-propanediol과 0.5 M sucrose가 포함된 동결액에 실온에서 10분간 노출 후 -30℃에서 30∼40분간 정치하여 급속동결하였을 때 발생율은 각각 26.6, 55.6, 65.0 및 52.9%로 2.5 M 1,2-propanediol에서 가장 높았으나, glycerol을 사용했을 때 보다 낮았다. 3. 토끼 상실배를 2.5, 3.0 및 3.5 M glycerol과 0.5 M trehalose가 포함된 동결액에 실온에서 10분간 노출후 액체질소에 침지하여 초급속동결한 결과 회수율은 각각 87.5, 92.5 및 92.5%, 형태적으로 정상인 수정란의 비율은 각각 37.5, 55.5 및 60.0%, 그리고 발생율은 각각 13.3, 36.4 및 37.5%로 3.5 M glycerol에서 가장 높았으나 초자화동결법보다 현저하게 낮았다. 4. 토끼 상실배를 25% glycerol과 25% 1,2-propanediol을 함유한 동결액에 실온에서 10분간 노출후 초자화동결했을 때 발생율은 75.0%로 실온에서 형평한 후 초자화동결이 가능하였다. This experiment was carried out to investigate on in vitro development of rabbit monla frozen by 2-step feezing and vitrification. The results obtained from this experiment are as follows; 1. When rabbit morula in m-PBS containing 1.5, 2.0, 2.5 or 3.0 M glyceral and 0.5 M sucrose for 10 min at room temperature were cooled at -30℃ for 30 to 40 min and plunged into liquid nitrogen, the proportion of embryo developed to expanded blastoyst was 36.4, 83.3, 92.3 and 84.2%, respectively. Glycerol 2.5 M showed higher survival than others. 2. When rabbit morula in m-PBS containing 1.5, 2.0, 2.5 or 3.0 M 1, 2-propanediol and 0.5 M sucrose for 10 min at room temperature were cooled at -30℃ for 30 to 40 min and plunged into liquid nitrogen, the proportion of embrye developed to expanded blastocyst was 26.6, 55.6, 65.0 and 52.9%, respectively. 1, 2-propanediol was less effective than glycerol. 3. When rabbit morula in m-PBS containing 2.5, 3.0 or 3.5 M glycerol and 0.5 M trehalose for 10 min at room temperature were plunged into liquid nitrogen and thawed rapidly, the recovery rate of embryo was 87.5, 92.5 and 92.5%, the proportion of morphologically normal embryo was 37.5, 55.5 and 60.0%, and the proportion of embryo developed to expanded blastocyst was 13.3. 36.4 and 37.5%, respectively. The proportion of embryo developed to expanded blastocyst was higher in vitrification than in plunging into liquid nitrogen. 4. When rabbit morula were frozen by vitrification in m-PBS containing 25% glycerol. 25% 1, 2-propanediol, the proportion of embryo developed to expanded blastocyst was 75.0%, the result suggested that rabbit embryos could be frozen by vitrification after equilibration at room temperature.

Bioconversion of major ginsenosides Rg₁ to minor ginsenoside F₁ using novel recombinant ginsenoside hydrolyzing glycosidase cloned from Sanguibacter keddieii and enzyme characterization

Kim, J.K.,Cui, C.H.,Yoon, M.H.,Kim, S.C.,Im, W.T. Elsevier Science Publishers 2012 Journal of biotechnology Vol.161 No.3

This study focuses on the cloning, expression, and characterization of recombinant ginsenoside hydrolyzing glycosidase from Sanguibacter keddieii in order to biotransform ginsenosides efficiently. The gene, termed bglSk, consists of 1857bp and revealed significant homology to that of glycoside hydrolase family 3. The enzyme was over-expressed in Escherichia coli BL21 (DE3) using a GST-fused pGEX 4T-1 vector system. The over-expressed recombinant enzymes could convert six major ginsenosides Rb<SUB>1</SUB>, Rb<SUB>2</SUB>, Rc, Rd, Re and Rg<SUB>1</SUB> into more pharmacologically active rare ginsenosides such as C-Y, C-Mc, C-K, Rg<SUB>2</SUB>(S), and F<SUB>1</SUB>. Especially, BglSk could completely convert the Rg<SUB>1</SUB> into F<SUB>1</SUB>. The GST-fused BglSk was purified with GST.bind agarose resin and then characterized. The kinetic parameters for β-glucosidase had apparent K<SUB>m</SUB> values of 0.456+/-0.009 and 0.167+/-0.003mM and V<SUB>max</SUB> values of 30.2+/-0.7 and 4.1+/-0.1μmolmin<SUP>-1</SUP>mg of protein<SUP>-1</SUP> against p-nitrophenyl-β-d-glucopyranoside and Rb<SUB>1</SUB>, respectively.

Nuclear analysis of structural damage and nuclear heating on enhanced K-DEMO divertor model

Park, J.,Im, K.,Kwon, S.,Kim, J.,Kim, D.,Woo, M.,Shin, C. International Atomic Energy Agency 2017 Nuclear fusion Vol.57 No.12

<P>This paper addresses nuclear analysis on the Korean fusion demonstration reactor (K-DEMO) divertor to estimate the overall trend of nuclear heating values and displacement damages. The K-DEMO divertor model was created and converted by the CAD (Pro-Engineer<SUP>™</SUP>) and Monte Carlo automatic modeling programs as a 22.5° sector of the tokamak. The Monte Carlo neutron photon transport and ADVANTG codes were used in this calculation with the FENDL-2.1 nuclear data library. The calculation results indicate that the highest values appeared on the upper outboard target (OT) area, which means the OT is exposed to the highest radiation conditions among the three plasma-facing parts (inboard, central and outboard) in the divertor. Especially, much lower nuclear heating values and displacement damages are indicated on the lower part of the OT area than others. These are important results contributing to thermal-hydraulic and thermo-mechanical analyses on the divertor and also it is expected that the copper alloy materials may be partially used as a heat sink only at the lower part of the OT instead of the reduced activation ferritic-martensitic steel due to copper alloy’s high thermal conductivity.</P>

Characteristic enhancement of white LED lamp using low temperature co-fired ceramic-chip on board package

Sim, J.K.,Ashok, K.,Ra, Y.H.,Im, H.C.,Baek, B.J.,Lee, C.R. Elsevier 2012 CURRENT APPLIED PHYSICS Vol.12 No.2

In this paper, we propose low temperature co-fired ceramic-chip on board (LTCC-COB) package with improved thermal characteristics; no insulation layer exists between the LED chip and metal base. In actual measurement as well as in thermal simulation, the proposed LED lamp structure showed excellent thermal properties, compared with surface mound device-printed circuit board (SMD-PCB) package LED lamp. The optical output power, thermal distribution, current-voltage (I-V) and electroluminescence (EL) were measured and compared to analyze the characteristics of LTCC-COB package LED lamp with SMD-PCB package LED lamp. EL peak intensity of LTCC-COB package LED lamp is 1.75 times better than that of SDM-PCB package LED lamp. The thermal resistance between packing area and air was found to be 7.3 K/W and 7.9 K/W for LTCC-COB package and SMD-PCB package respectively. The proposed LTCC-COB packaged LED lamp is not only suitable for high power LED package due to its low thermal resistance but also a promising solution for illumination modules.

동결속도와 평형시간이 소 미성숙 난자의 동결 융해후 생존율에 미치는 영향

양병철,양보석,성환후,임기순,최선호,장원경,진동일,임경순 한국가축번식학회 2001 Reproductive & developmental biology Vol.25 No.1

The present study was undertaken to investigate the effects of cooling rate and equilibration time on the survival, in vitro maturation and development to embryos of frozen-thawed bovine immature oocytes(Germinal Vesicle Stage). The cryoprotectants are used 10% ethylene glycol(EG) as permeating cryoprotectant and 0.05M sucrose(S) or trehalose(T) as low molecular weight nonpermeating cryoprotectants and 5% ficoll(F) or polyvinylpyrrolidone(PVP) as high molecular weight nonpermeating cryoprotectants. Four freezing solution were uysed in this experiment(EFT: 10% EG + 5% F + 0.05M T, EFS: 10% EG + 5% F + 0.05M S, EPT: 10% EG + 5% P + 0.05M T, EPS: 10% EG + 5% P + 0.05M S). The best equilibration time and freezing solution was 15 min in EPT(83% survival rate of frozen-thawed bovine immature oocytes). When frozen-thawed bovine oocytes were cultured following IVM and IVF, there was no significant difference in cleavage and development rates among the EFT, EFS, EPT and EPS solutions. When 9 blastocysts derived from frozen bovine oocytes were transferred to 6 recipients, two recipients were pregnant. And one was aborted at 45 days of pregnancy and the other had a stillbirth.