Separation of tetrahydrofuran and water using pressure swing distillation: Modeling and optimization

Jihwan Lee,조정호,김동민,박상진 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

Computer simulations were performed to obtain highly pure tetrahydrofuran (THF) with over 99.9 mole%from the mixture of THF and water. Pressure swing distillation (PSD) was used since the azeotropic point between tetrahydrofuran and water can be varied with pressure. A commercial process simulator, PRO/II with PROVISION release 8.3, was used for the simulation studies. The Wilson liquid activity coefficient model was used to simulate the low pressure column, and the Peng-Robinson equation of state model was added to correct the vapor phase non-idealities for the modeling of the high pressure column. The most optimal reflux ratios and the most optimal feed stage locations that could minimize the total reboiler heat duties were determined.

Effects of Maternal Thermal Stress on the Number of Retrieved Oocytes by Ovum Pick Up and Subsequent Embryo Development in Dairy Cattle

Jihwan LEE,Kyungsuk LEE,Doosan KIM,Junkyu SON,Jian LEE,Jinju KIM,Gulwon JANG,Manhye HAN 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10

High environmental temperatures observed during the summer month reduce bovine reproduction and fertility. In this study, we examined the effect of maternal thermal stress on the number of immature oocytes retrieved by OPU procedure from Jersey heifers and their subsequent embryo developmental competence. Total 57, 69, 81 immature oocytes were retrieved from same donors (n = 3) in May (spring), June (early summer) and July (summer), respectively. Blastocyst rates were 33.3, 34.8 and 24.8% in spring, early summer and summer, respectively. Interestingly, we observed that the number of retrieved oocytes from donors were higher under extreme hot temperature (summer) than moderated temperature (spring). In contrast, blastocyst rates were lower under the hot weather. It is presumed that the reason for the increased number of retrieved oocytes in summer is associated with increased FSH levels by reduced progesterone levels due to impaired corpus luteum. And reduced embryo developmental competence in hot weather is thought to be associated with disruption of nuclear and cytoplasmic maturation. Taken together, our result suggest that maternal thermal stress affects the number of retrieved oocytes from dairy heifers and embryo developmental competence.

A Case Study on Clearance of Radioactive Material and Removal of Non-radioactive Material From the Decommissioning NPPs in Germany

Jihwan Yu,Hyung-woo Seo,Gi-lim Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

The operation and decommissioning of nuclear power plants (NPPs) creates waste in the process of handling radioactively contaminated material, which must be disposed of in a repository or can be recovered of in the same way as conventional waste in the course of handling radioactively contaminated materials. For buildings or sites of NPPs it also has to be decided under what conditions they can continue to be used for other, conventional purposes or demolished. This decision is referred to as “release from supervision under nuclear and radiation protection law” or “clearance” in short. The clearance levels applicable in Germany according to the Radiation Protection Ordinance have been defined such that a radiation dose (hereinafter referred to as “dose”) of 10 μSv per year is not exceeded. The vast majority of the materials resulting from the dismantling of a nuclear power plant (e.g. most of the massive concrete structures) are neither contaminated nor activated. Thus, there is no need to treat these materials as radioactive waste. Emplacement of uncontaminated masses which in Germany is essentially several million tonnes of building rubble in a repository would require additional construction of such facilities, which, in view of the negligible hazard potential, from the point of view of the Nuclear Waste Management Commission (ESK) is clearly to be rejected both economically and, in particular, ecologically. Alternative ways are increasingly discussed in public, such as the abandonment of buildings after gutting, i.e. refraining from demolition of the controlled area buildings of NPPs. Also, another proposal discussed in public, the landfilling or the long-term storage of cleared material at the site, does not offer any safety-related advantages either in the view of the ESK. If, after completion of all dismantling work, the building has been decontaminated such that the clearance levels for buildings are complied with further use of the building rubble resulting from demolition is harmless from a radiological point of view. For these reasons, Germany has deliberately decided to use clearance as an essential measure in the dismantling of NPPs. If it is intended to conventionally reuse or depose of virtually contaminant-free material from controlled areas, it must first undergo a clearance procedure. The prerequisites that must be fulfilled for clearance are regulated in the Radiation Protection Ordinance, which includes two basic clearance pathways: unrestricted and specific clearance. In the following, the basic process of clearance is briefly presented and illustrated for a better understanding. It comprises five steps. Step 1-Radiological characterization by sampling, Step 2-Dismantling of plant components in the controlled area, Step 3- Decontamination, Step 4-Decission measurements, Step 5-Clearacnce and further management. The entire clearance process is governed by a clearance notice and is carried out under the supervision of the competent authority under nuclear and radiation protection law or the independent authorized expert commissioned by it. The clearance pathways contained in the Radiation Protection Ordinance have proven themselves in practice. They permit safe and proper management of material from dismantling and release of the site from supervision under nuclear and radiation protection law. These German regulatory procedures should be taken into account and deregulation and removal should be used as appropriate and necessary tools in the process of decommissioning NPPs in order to return non-hazardous materials to the material cycle or for conventional disposal.

Effect of sintering temperature on the formation of epsilon Fe₂O₃ nanoparticles encapsulated by SiO₂

Jihwan Seol,Phuoc Cao Van,Trinh Nguyen Thi,Jong Ryul Jeong 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Coded-aperture based Dual Particle Imager for the Measurement of Dose Rate of Both Gamma-ray and Neutron

Jihwan Boo,Seoryung Park,Suyeon Hyeon,Chae minki,Manhee Jeong 대한방사선방어학회 2021 대한방사선방어학회 학술발표회 논문요약집 Vol.2021 No.11

Isolation of Temperature-sensitive Mutant Escherichia coli YrdC Involved in Universal t<SUP>6</SUP>A tRNA Synthesis

Jihwan Hwang(황지환) 한국생명과학회 2018 생명과학회지 Vol.28 No.2

YrdC 수퍼 패밀리는 지금까지 유전 서열이 알려진 거의 모든 생명체에서 매우 잘 보존 된 단백질 중 하나이다. Escherichia coli의 YrdC는 리보솜 생합성, 번역 종결, 저온 적응, tRNA에서 threonylcarbamoyl adenosine의 형성에 관여하는 것으로 제안되었다. 이 연구에서, yrdC 유전자가 대장균에서 필수적이라는 것을 명확하게 증명하기 위해, 대장균에서 두 개의 yrdC 결손 돌연변이 균주를 만들고 그 표현형을 조사하였다. 특히 온도에 민감한 yrdC 돌연변이 균주는 42°C 온도 조건 하에서 거의 즉시 세포 성장을 멈추었으며 30S 리보솜 단위체의 상당한 축적없이 16S rRNA 전구체를 축적하는 것으로 나타났다. 또한 효모와 인간의 yrdC 유전자를 클로닝하여 이들이 대장균 yrdC 결손 균주의 성장억제를 회복 할 수 있다는 것을 입증하였다. 이밖에도 여러 돌연변이 연구에 의해, 우리는 YrdC 단백질의 중간에 위치한 오목한 표면이 대장균, 효모 및 인간의 YrdC 단백질에서 중요한 역할을 한다는 것을 보여주었다. 따라서, 두 개의 yrdC 결손 균주를 비교하여, yrdC 유전자가 대장균에서 생존력에 필수적이며, 효모 및 인간 동족체의 기능이 대장균 YrdC의 기능과 중복된다는 것을 규명하였고, 이 균주를 이용하여 아직까지 밝혀지지 않은 대장균 YrdC 단백질이 tRNA 형성에 관여한다는 것을 증명할 수 있는 토대를 제공한다는데 의의가 있다. The YrdC superfamily is a group of proteins that are highly conserved in almost all organisms sequenced so far. YrdC in Escherichia coli was suggested to be involved in ribosome biogenesis, translation termination, cold adaptation, and threonylcarbamoyl adenosine formation in tRNA. In this study, to unambiguously demonstrate that yrdC is essential in E. coli, we constructed two yrdC mutant strains of E. coli and examined their phenotypes. In the temperature-sensitive yrdC mutant strain, cell growth stopped almost immediately under nonpermissive conditions and it appeared to accumulate 16S ribosomal RNA precursors without significant accumulation of 30S ribosomal subunits. We also cloned yeast and human homologs and demonstrated that they complement the E. coli yrdC-deletion strain. By mutational study, we demonstrated that the concave surface in the middle of the YrdC protein plays an important role in E. coli, yeast, and human versions. By comparison of two yrdC-deletion strains, we also unambiguously demonstrated that yrdC is essential for viability in E. coli and that the functions of its yeast and human homologs overlap with that of E. coli YrdC.

Normalization of Inter-Korean Relations to Lay Foundations of Unification

Jihwan Hwang Ewha Institute of Unification Studies 2014 Journal of peace and unification Vol.4 No.2

The Park Geun Hye government has explained the trust-building process on the Korean Peninsula as “a policy to develop South-North relations by building trust based on solid security, settling peace on the peninsula, and further building foundations for unification.” However, the tasks of normalization of inter-Korean relations have been dealt not for unification in the long-term level but short-term development, staying in improving the relations of two Koreas. So, most of the policy issues have not successfully introduced and implemented from a long-term strategic perspective on unification due to the constraints that inter-Korean relations have. In view of this, the detailed and various tasks of normalizing inter-Korean relations to build unification foundation need to be re-arranged as new promotion strategy. Under the diverse principles of pushing them ahead and the basics of driving directions, the works to be done for normalizing inter-Korean relations are necessary to be presented in phases separated by three steps. The principles of the normalizing relationship between South and North may present their methodological directions based on the three promotional principles of the Korean Peninsula trust-building process proposed by the government in terms of policy coherence and efficiency in the process of unification.

Business Model Mining : Analyzing a Firm’s Business Model with Text Mining of Annual Report

Jihwan Lee,Yoo S. Hong 대한산업공학회 2014 Industrial Engineeering & Management Systems Vol.13 No.4

As the business model is receiving considerable attention these days, the ability to collect business model related information has become essential requirement for a company. The annual report is one of the most important external documents which contain crucial information about the company’s business model. By investigating business descriptions and their future strategies within the annual report, we can easily analyze a company’s business model. However, given the sheer volume of the data, which is usually over a hundred pages, it is not practical to depend only on manual extraction. The purpose of this study is to complement the manual extraction process by using text mining techniques. In this study, the text mining technique is applied in business model concept extraction and business model evolution analysis. By concept, we mean the overview of a company’s business model within a specific year, and, by evolution, we mean temporal changes in the business model concept over time. The efficiency and effectiveness of our methodology is illustrated by a case example of three companies in the US video rental industry.

Wireless remote controled excavator using haptic technology

( Jihwan Kwon ),( Migyung Park ),( Chaeyoung Lee ),( Seongjin Han ),( Seungnam Min ) 한국감성과학회 2017 한국감성과학회 국제학술대회(ICES) Vol.2017 No.-

Excavators or loaders are widely used in construction sites. The excavator or loader operator does not have an overall vision from the cabin to the area around the machine. Hence, there are possibilities for collision accidents between the machine and humans or obstacles. Another issue with excavator or loader is vibration and noise. Reducing the exposure to human body vibration is one of the most significant ways to improve the ride quality. Recent technological developments have aimed to increase the operator visibility from the cabin to the area around the machine through direct or indirect visibility aids. Our work aimed to approach the problem of excavators’ operator visibility in an alternative way. We are developing a haptic hand to control or operate the machine from the outside of the machine instead of from the cabin. The haptic hand is a greatly simplified robotic hand which is designed to mirror the human hand. This development can improve the operator visibility as well as can avoid exposure to vibration to the operator.

Distributed Coding Scheme for Multi-view Video through Efficient Side Information Generation

Jihwan Yoo,Min Soo Ko,Soon Chul Kwon,Young-Ho Seo,Dong-Wook Kim,Jisang Yoo 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

In this paper, a distributed image coding scheme for multi-view video through an efficient generation of side information is proposed. A distributed video coding technique corrects the errors in the side information, which is generated with the original image, by using the channel coding technique at the decoder. Therefore, the more correct the generated side information is, the better the performance of distributed video coding. The proposed technique is to apply the distributed video coding schemes to the image coding for multi-view video. It generates side information by selectively and efficiently using both 3-dimensional warping based on the depth map with spatially adjacent frames and motion-compensated temporal interpolation with temporally adjacent frames. In this scheme the difference between the adjacent frames, the sizes of the motion vectors for the adjacent blocks, and the edge information are used as the selection criteria. From the experiments, it was observed that the quality of the side information generated by the proposed technique was improved by the average peak signal-to-noise ratio of 0.97dB than the one by motion-compensated temporal interpolation or 3-dimensional warping. The result from analyzing the rate-distortion curves revealed that the proposed scheme could reduce the bit-rate by 8.01% on average at the same peak signal-tonoise ratio value, compared to previous work.