황-요오드 수소 제조 공정에서 초음파 조사를 이용한 분젠 반응의 특성

김효섭 ( Hyo Sub Kim ),이동희 ( Dong Hee Lee ),이종규 ( Jong Gyu Lee ),박주식 ( Chu Sik Park ),김영호 ( Young Ho Kim ) 한국공업화학회 2018 공업화학 Vol.29 No.1

황-요오드(SI) 공정의 통합 운전을 위한 분젠 반응 단계에서, I₂ 및 H₂O 반응물들은 HI_x 용액 내 용해된 성분들로써 공급된다. HI_x 용액과 SO₂ 공급을 이용하여 분젠 반응이 수행될 때 HI_x 상 내 대부분의 H₂SO₄ 생성물이 존재하며, 이에 따라 HI_x 상에 대한 H₂SO₄ 상의 부피 비가 매우 낮다. 본 연구에서 우리는 상 분리 성능을 향상시키기 위해 HI_x용액을 이용한 분젠 반응에 대한 초음파 조사의 효과들을 연구하였다. 분젠 반응과 함께 초음파가 조사될 때 HI_x 상으로부터 H₂SO₄ 상으로 이동된 H₂SO₄의 양은 최대 58.0 mol%까지 증가하였으며, H₂SO₄ 상의 부피 또한 최대 13.1 vol%까지 증가하였다. 특히, 상 분리에 대한 초음파 조사의 효과는 온도, I₂ 및 H₂O 공급 농도가 감소함에 따라 향상되었다. 초음파 조사는 HI_x 상 내 반응 평형을 미시적으로 이동시킴으로써 추가적인 H₂O 분자들의 형성을 유도하였다. 이로부터 추가적으로 생성된 H₂O 및 분리된 H₂SO₄ 분자들이 H₂SO₄ 상으로 이동할 수 있는 더 많은 H₂SO₄·xH₂O (x = 5-6) 착물들을 형성하였다. In Bunsen reaction section for the integrated operation of sulfur-iodine (SI) process, I₂ and H₂O reactants are supplied as dissolved species in an HI_x solution. Most of the H₂SO₄ product is found in the HI_x phase when Bunsen reaction is performed using the HI_x solution and SO₂ feed, so that the volume ratio of the H₂SO₄ phase to the HI_x phase is very low. In this study, we investigated the effects of ultrasound irradiation on Bunsen reaction using the HI_x solution to improve its phase separation performance. With ultrasound irradiation, the amount of H₂SO₄ moved to the H₂SO₄ phase from the HI_x phase increased by up to 58.0 mol% and the volume of H₂SO₄ phase also increased by up to 13.1 vol%. In particular, the effect of ultrasound irradiation on the phase separation was improved with decreasing operating temperature, I₂ and H₂O feed concentrations. The ultrasound irradiation induces the formation of additional H₂O molecules by shifting microscopically the reaction equilibrium in the HI_x phase. Afterward, the additionally generated H₂O and isolated H₂SO₄ molecules form more H₂SO₄·xH₂O (x = 5-6) clusters that can be moved to the H₂SO₄ phase.

Effects of operating parameters on the pressurized Bunsen reaction for the integrated operation of sulfur–iodine hydrogen production process

Kim, Hyo Sub,Park, Hyun Kyu,Kim, Young Ho,Park, Chu Sik,Bae, Ki Kwang Elsevier 2016 International journal of hydrogen energy Vol.41 No.34

<P><B>Abstract</B></P> <P>The sulfur–iodine hydrogen production process (SI process) is an efficient thermochemical process. Developing composition data of the Bunsen products that are obtained under pressurized conditions is important for the integrated operation of SI process. We investigated the characteristics of the pressurized Bunsen reaction by varying operating parameters (pressure, temperature, I<SUB>2</SUB> and H<SUB>2</SUB>O feed concentrations). An HI<SUB>x</SUB> solution that consisted of HI, I<SUB>2</SUB> and H<SUB>2</SUB>O was used as the reactant. When the pressure increased, the extent of Bunsen reaction was enhanced by increasing the solubility of SO<SUB>2</SUB> gas in the HI<SUB>x</SUB> solution. In addition, the amount of H<SUB>2</SUB>SO<SUB>4</SUB> phase solution increased due to the decrease in the amount of HI<SUB>x</SUB> complex, which has a high degree of hydration. Increasing temperature enhanced the separation performance of the Bunsen products, while the extent of Bunsen reaction decreased. When I<SUB>2</SUB> feed concentration increased, the occurrence of side reaction was inhibited, but the separation performance of the Bunsen products decreased. Although increasing H<SUB>2</SUB>O feed concentration was favorable for the pressurized Bunsen reaction, the H<SUB>2</SUB>O feed concentration should be controlled by considering the solubility of I<SUB>2</SUB> in the HI<SUB>x</SUB> solution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The characteristics of the pressurized Bunsen reaction was investigated. </LI> <LI> Increasing the pressure enhanced the separation performance of the products. </LI> <LI> The purity of the product improved as the temperature increased. </LI> <LI> Increasing I<SUB>2</SUB> feed concentration inhibited the occurrence of side reaction. </LI> <LI> The extent of Bunsen reaction improved by increasing H<SUB>2</SUB>O feed concentration. </LI> </UL> </P>

A convenient method for phase separation and composition determination of the Bunsen reaction products in sulfur-iodine hydrogen production process

Kim, Hyo Sub,Park, Hyun Kyu,Kim, Young Ho,Lee, Jong Gyu,Park, Chu Sik,Bae, Ki Kwang Elsevier 2017 International journal of hydrogen energy Vol.42 No.7

<P><B>Abstract</B></P> <P>During the integrated operation of the sulfur-iodine process, it is important to conveniently and quickly measure the composition of the Bunsen reaction products and to ascertain the location of each phase in the liquid–liquid phase separator. First, the method to determine each composition in HI<SUB>x</SUB> phase system which contains four components of HI, I<SUB>2</SUB>, H<SUB>2</SUB>O, and H<SUB>2</SUB>SO<SUB>4</SUB> was newly proposed using only the data of H<SUP>+</SUP> and I<SUP>−</SUP> contents and the density of the HI<SUB>x</SUB> phase. This method has the advantage to replace the complicated and time-consuming traditional titration step of I<SUB>2</SUB>. The calculated I<SUB>2</SUB>/HI molar ratios were within an error of ±5% at all temperature conditions, indicating that this method was suitable for I<SUB>2</SUB> composition analysis. Meanwhile, the use of an electrical conductivity sensor was discussed as a sensing technology during the phase separation of Bunsen reaction products. The electrical conductivity was measured using different compositions of the Bunsen reaction products. The conductivity difference between H<SUB>2</SUB>SO<SUB>4</SUB> and HI<SUB>x</SUB> phase solutions was approximately 478–822 mS/cm in the main compositional range of the Bunsen reaction products. Therefore, this method can replace the traditional phase separation method using a DP (differential pressure) cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The convenient determination method of the product composition was proposed. </LI> <LI> The I<SUB>2</SUB>/HI molar ratios calculated by the new method were within an error of ±5%. </LI> <LI> The use of an electrical conductivity sensor was discussed as a sensing technology. </LI> <LI> The electrical conductivity sensor can replace the traditional phase separation method. </LI> <LI> The schematic diagram of a liquid–liquid phase separator was proposed. </LI> </UL> </P>

TEOS/염기 및 MTMS/산 혼성 용액으로 제조한 반사방지 코팅막의 특성

박현규 ( Hyun-kyu Park ),김효섭 ( Hyo-sub Kim ),박주식 ( Chu-sik Park ),김영호 ( Young-ho Kim ) 한국공업화학회 2019 공업화학 Vol.30 No.3

반사 방지(anti-reflective; AR) 코팅막의 광학 특성 및 내오염성을 향상하기 위하여 tetraethylorthosilicate (TEOS)/염기 및 methyltrimethoxysilane (MTMS)/산 혼성 용액의 혼합비를 변화시키며 다양한 AR 코팅막을 제조하였다. 제조된 AR 코팅막은 UV-Vis, 접촉각 측정기, AFM, FT-IR 및 연필 경도 시험을 통해 특성을 분석하였다. MTMS/산 용액의 함량이 10 wt%인 혼성 용액으로 제조한 AR 코팅막에서 유리 기판은 매우 우수한 광학 특성(97.2%의 투과율), 우수한 내오염성(121°의 물 접촉각 및 90°의 CH₂I₂ 접촉각), 중간 정도의 기계적 강도(4 H의 연필 경도)를 나타내었다. 특히 우수한 내오염성은 기판의 표면 위에서 혼성 용액 내 소량의 MTMS/산 용액으로부터 유래된 메틸기(-CH₃)의 고른 분산에 기인한 것으로 고려되었다. 연필 경도 시험 결과로부터, AR 코팅막의 기계적 강도는 MTMS/산 용액의 함량이 증가할수록 향상되는 것으로 나타났다. To improve the optical characteristics and antifouling of anti-reflective coating (AR) films, various AR coating films were prepared by varying the mixing ratio of tetraethylorthosilicate (TEOS)/base and methyltrimethoxysilane (MTMS)/acid hybrid solution. Prepared AR coating films were characterized by UV-Vis spectroscopy, contact angle analyzer, atomic force microscope (AFM), FT-IR and pencil scratch hardness test. In an AR coating film that prepared from the hybrid solution with a 10 wt% MTMS/acid solution, the glass substrate showed an excellent optical property (97.2% transmittance), good antifouling (121° water contact angle and 90° CH₂I₂ contact angle) and moderate mechanical strength (pencil hardness of 4 H). In particular, it is considered that the good antifouling was due to the well dispersion of the methyl group (-CH₃), derived from a small amount of MTMS/acid solution in the hybrid solution, on the substrate surface. From results of the pencil hardness test, the mechanical strength of AR coating film was improved as the content of MTMS/acid solution increased.

Genetic Diversity of Common Reed in Korea Based on Morphological Characteristics and Random Amplified Polymorphic DNA Markers

Chu, Hyo-Sub,Cho, Won-Kyong,Rim, Yeong-Gil,Jo, Yeon-Hwa,Kim, Jae-Yean The Plant Resources Society of Korea 2011 한국자원식물학회지 Vol.24 No.6

To elucidate genetic diversity of common reed in Korea, we collected a total of 674 common reed plants from 27 regions in South Korea. Hierarchical clustering using 7 morphological traits divided the 27 common reed populations into 7 groups. Random amplified polymorphic DNA (RAPD) results identified three distinct groups of common reed. Common reed accessions in group I mostly inhabit coastal areas. Group II includes reeds mostly collected from inland areas. Group III consists of common reed accessions collected from inland and coastal areas, suggesting that this group might contain hybrids. In summary, we suggest that parapatric speciation might be an important factor in the genetic diversity of common reed and geographical speciation of common reed that might be also affected by environmental gradients.

CoAPSO-34 촉매상에서 DTO (Dimethyl Ether to Olefins) 반응에 미치는 Co/Al 및 Si/Al 몰 비의 영향

김효섭 ( Hyo Sub Kim ),이수경 ( Su Gyung Lee ),최기환 ( Ki Hwan Choi ),이동희 ( Dong Hee Lee ),박주식 ( Chu Sik Park ),김영호 ( Young Ho Kim ) 한국공업화학회 2015 공업화학 Vol.26 No.2

Effects of Co/Al and Si/Al molar ratios of cobalt incorporated SAPO-34 catalysts (CoAPSO-34) on their catalytic lifetime were investigated in dimethyl to olefin (DTO) reaction. The property of CoAPSO-34 catalysts was characterized using XRD, SEM, 29Si MAS NMR, and NH3-TPD techniques. First, the lifetime of CoAPSO-34 prepared by varying Co/Al molar ratios was improved than that of using the SAPO-34 catalyst, and the optimal Co/Al molar ratio was 0.0025. The total acid site amounts increased from 0.432 to 1.111 mmol/g with increasing Si/Al molar ratios from 0.05 to 0.20 while fixing a Co/Al molar ratio of 0.0025. However, the catalysts with too high acid site amounts were deactivated rapidly with blockages of the pores due to the fast accumulation of polycyclic aromatic hydrocarbons in the cage. Therefore, the CoAPSO-34 catalyst with a proper Si/Al molar ratio of 0.10 was the most superior in terms of the lifetime, which was improved by about 87% as compared with that of the SAPO-34 catalyst.

Methyltrimethoxysilane을 이용한 반사방지 코팅막의 성능 향상

금영섭 ( Young Sub Keum ),김효섭 ( Hyo Sub Kim ),박주식 ( Chu Sik Park ),김영호 ( Young Ho Kim ) 한국공업화학회 2015 공업화학 Vol.26 No.4

Traditional anti-reflective (AR) coating films prepared using tetraethylorthosilicate (TEOS) as a precursor absorbs water easily in addition to having a weak abrasion resistance. To improve the transmittance, hydrophobicity and abrasion resistance of AR coating film, various AR coating films were prepared using methyltrimethoxysilane (MTMS) as a precursor in addition to introducing a fluoroalkylsilane, acid catalyst, base catalyst and acid-base two step catalyst. The prepared AR coating films were then characterized by UV-Vis spectroscopy, contact angle analyzer, atomic force microscope (AFM), pencil scratch hardness test and cross-cut test. As a result, the transmittance of bare glass was 90.5%, while that of AR coating glass increased to 94.8% at curing temperature of 300 ℃. When the fluoroalkylsilane was added, the water contact angle of AR coating film increased from 96.3° to 108°, indicating that the hydrophobicity of the film was greatly improved. The abrasion resistance of AR coating film was also improved by the acid catalyst, whereas the transmittance increased by the base catalyst. In the case of AR coating film prepared using an acid-base two step catalyzed reaction, both the transmittance and abrasion resistance of the film was synergistically enhanced as compared with those of AR coating films prepared without introduction of a catalyst.

Optoelectronic and microwave transmission characteristics of indium solder bumps for low-temperature flip-chip applications

Kun-Mo Chu,Jung-Hwan Choi,Jung-Sub Lee,Han Seo Cho,Seong-Ook Park,Hyo-Hoon Park,Duk Young Jeon Institute of Electrical and Electronics Engineers 2006 IEEE transactions on advanced packaging Vol.29 No.3

<P>This paper describes low-temperature flip-chip bonding for both optical interconnect and microwave applications. Vertical-cavity surface-emitting laser (VCSEL) arrays were flip-chip bonded onto a fused silica substrate to investigate the optoelectronic characteristics. To achieve low-temperature flip-chip bonding, indium solder bumps were used, which had a low melting temperature of 156.7degC. The current-voltage (I-V) and light-current (L-I) characteristics of the flip-chip bonded VCSEL arrays were improved by Ag coating on the indium bump. The I-V and L-I curves indicate that optical and electrical performances of Ag-coated indium bumps are superior to those of uncoated indium solder bumps. The microwave characteristics of the solder bumps were investigated by using a flip-chip-bonded coplanar waveguide (CPW) structure and by measuring the scattering parameter with an on-wafer probe station for the frequency range up to 40 GHz. The indium solder bumps, either with or without the Ag coating, provided good microwave characteristics and retained the original characteristic of the CPW signal lines without degradation of the insertion and return losses by the solder bumps</P>

물-공기 횡류시 U 자형 튜브 다발에서의 유체탄성불안정

주인철(In-Cheol Chu),정흥준(Heung June Chung),이창희(Chang Hee Lee),윤영중(Young Jung Yun),정한섭(Han-Sub Chung),변형현(Hyung Hyun Byun),김무용(Moo Yong Kim),문효익(Hyo Ik Moon),이희남(Hui Nam Rhee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

In the present study, a series of experiments have been performed to investigate a fluid-elastic instability of an U-tube bundle in air-water two-phase cross-flow. A total of 39 prototypic U-bend tubes are arranged in a rotated square array with a p/d of 1.633, which is identical to U-bend tube bundle of OPR1000 steam generators. The present experimental facility has 2-span U-tubes in contrast to 9-span U-tubes of OPR1000 steam generators. However, modal analysis shows that the major vibration mode and corresponding natural frequencies are almost same to the full 9-span U-tubes. A total of 12 3-axis acceleromters are installed inside U-tubes to monitor a precise vibration motions. The following parameters were obtained throughout a series of experiments: tube vibration responses and critical velocity for fluid-elastic instability, two-phase damping ratio, hydrodynamic mass. Finally, the instability factor (K) of Connors’ relation was evaluated based on the above measured parameters.

미생물 혼입 자기치유 콘크리트의 균열 치유성능 및 내구성능

추인엽,우상균,이병재,이윤,이효섭,Chu, Inyeop,Woo, Sang-Kyun,Lee, Byung-Jae,Lee, Yun,Lee, Hyo-Sub 한국전력공사 2021 KEPCO Journal on electric power and energy Vol.7 No.2

Recently, interest in maintenance has been increasing due to the enlargement and aging of infra structures. Therefore, a new paradigm is required to secure and improve the durability of structures differentiated from the past. Accordingly, research on smart concrete incorporating the concept of self-healing into concrete is being actively conducted. In this study, the crack healing performance and durability performance of self-healing concrete applied with a hydrogel containing biomineral-forming microorganisms were evaluated. As a result of evaluating the dispersion of the hydrogel in concrete, it was confirmed that the hydrogel was well distributed in concrete matrix with a dispersion coefficient of 0.35 to 0.46. The crack healing performance evaluation was verified by a water permeability test, and showed a recovery rate of 95% or more at the age of 28 days, confirming the applicability of self-healing concrete. The durability performance of self-healing concrete was evaluated in terms of resistance to penetration of chloride ion and freezing and thawing. Regardless of the mixing of the hydrogel, the same level of durability performance was shown for various compressive strength level. Therefore, it was confirmed that the microbial admixture did not affect concrete durability. In the future, long-term crack healing performance and durability verification studies should be supplemented.