• 한국미생물·생명공학회지
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• 제51권4호
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• pp.333-352
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• 2023

Transaminase represents the most important biocatalysts used for the synthesis of chiral amines due to their stereoselectivity. They allow asymmetric synthesis with high yields and enantioselectivity from their corresponding ketones. Due to their environmentally friendly access for the preparation of chiral amines, they have attracted growing attention in recent times. Thus, the production of chiral compounds by transaminase catalysed reactions is considered as an important application in synthetic organic chemistry. Therefore, transaminase is considered to be an important enzyme in the pharmaceutical and chemical industries. ω-Transaminase holds great potential because of its wide substrate specificity thus making it a suitable enzyme to be used at an industrial scale. This review highlights the reaction mechanism, classification, substrate specificity, and biochemical properties. The review also showcases the application of ω-transaminase in organic chemistry with a focus on the production of active pharmaceutical ingredients (APIs).

• Journal of Korean Neurosurgical Society
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• 제29권8호
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• pp.985-994
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• 2000

Objective : There are some advantages of trigeminal evoked potential(TEP) recording compared to other somatosensory evoked potential(SSEP) recordings. The trigeminal sensory pathway has a pure sensory nerve branch, a broader receptive field in cerebral cortex, and a shorter pathway. Despite these advantages, there is little agreement as to what constitutes a normal response and what wave forms truly characterize the intraoperative TEP. This study presents the normative data of TEP recorded on the epidural surface of the rat with a platinum ball electrode. Materials & Methods : Under general anesthesia with urethane, the adult Sprague-Dawley male rats(300-350g) were given electrical stimulation with two stainless steel electrodes which were inserted into the subcutaneous layer of the area around whiskers. A reference electrode was positioned in the temporalis muscle ipsilateral to the recording site. Results : TEPs were recorded in the Par I area of somatosensory cortex and recorded most apparently on the point of 2mm posterior from the bregma and 6mm lateral from the midline. The typical wave form consisted of 5 peaks (N1-P1-N2-P2-N3 according to emerging order, upward negativity). Each latency to corresponding peaks was not influenced by the different intensities of stimulation, especially from 1 to 5mA. Average latencies of 5 peaks were in the following order ; 7.7, 11.1, 15, 22.3, 29.4ms. There was also no significant difference between latencies before and after administration of muscle relaxant(pancuronium). For the electrophysiological localization of recorded waves, the action potential of a single unit was recorded with glass microelectrode(filled with 2M NaCl, $3-5M{\Omega}$) in the thalamus of rat. A sharp wave was recorded in the VPM nucleus, in which the latency was shorter than that of N1. This suggests that all 5 peaks were generated by neural activities in the suprathalamic pathway. Conclusion : In terms of recording near-field potentials, our data also suggests that TEP in the rat may be superior to other SSEPs. In overall, these results may afford normative data for the studies of supratentorial lesions such as hydrocephalus or cerebral ischemia which can have an influence on near-field potentials.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.139.1-139.1
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• 2016

Multiferroic materials are of great interest because of its potential applications in the design of devices combining magnetic, electronic and optical functionalities. Among various multiferroic materials, $BiFeO_3$(BFO) is known to be one of the intensively focused mainly due to the possibility of multiferroism at device working temperature (> $200^{\circ}C$). However, leakage current and weak polarization resulting from oxygen deficiency and crystalline defect should be resolved. Furthermore the magnetic ordering of pure BFO mainly prefers to have antiferromagnetic coupling. Up to now many attempts have been performed to improve the ferromagnetic and the ferroelectric properties of BFO by doping. In this work, we investigated the effects of Ni substitution on the multiferroism of bulk BFO. Four BFO samples (a pure BFO and three Ni-doped BFO's; $BiFe_{0.99}Ni_{0.01}O_3$, $BiFe_{0.98}Ni_{0.02}O_3$ and $BiFe_{0.97}Ni_{0.03}O_3$) were synthesized by the standard solid-state reaction and rapid sintering technique. The XRD results reveal that Ni atoms are substituted into Fe-sites and give rise to phase transition of cubic to rhombohedal. By using vibrating sample magnetometer and standard ferroelectric tester, the multiferroic properties at room temperature were characterized. We found that the magnetic moment of Ni-doped BFO turned out to be maximized for 3% of Ni dopant.

• 수산경영론집
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• 제46권2호
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• pp.111-125
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• 2015

This study is to analyze the efficiency of Korean sea food manufacturing using Data Envelopment Analysis. Firstly, based on an output oriented traditional CCR, BCC model, the study estimated the efficiency scores. The average estimates of technical, pure technical, and scale efficiency turned out 0.6517, 0.7184, 0.9074 respectively, which are separated for 50 marine corporations. The 10 DMUs were efficient under CCR model while the 17 DMUs under BCC model. Also, the study suggested that the operating profit of the two output factors should be more increased relatively and averagely from the viewpoint of efficiency improvement. Secondly, super efficiency scores are estimated under super efficiency and SBM model. As a result, it came to be possible to distinguish and rank the efficiency of the efficient DMUs. The highest score was 4.2975 under Super-CCR, was 2.4947 under Super-BCC, was 2.7160 under SBM-Super-CCR, and was 1.5319 under SBM-Super-BCC model. The average estimates of super efficiency were 0.76 and 0.82 under Super-CCR and Super-BCC model respectively, and were 0.61 and 0.67 under SBM-Super-CCR and SBM-Super-BCC model. Finally, the study conducted a rank-sum test, Wilcoxon-Mann-Whitney test, to find a statistical significance of heterogeneity existing in efficiencies among the sample corporations. The result showed that there was a significant difference in average efficiency between Dried, Salted product manufacturing and Frozen product manufacturing under BCC-Super efficiency model at 10% level of significance. Furthermore, TOBIT model was applied to find out the potential factors that might influence the efficiency, Wilcoxonand the results showed debt and sales cost influenced all of the technical, pure technical, and scale efficiency, while net profit influenced only the technical efficiency.

• Journal of Chest Surgery
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• 제15권2호
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• pp.204-212
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• 1982

The presence of left atrial thrombus in mitral stenosis has been reported to be associated with several factors. These are age, sex, presence of atrial fibrillation, episodes of congestave heart failure, calcification of mitral valve, embolic episode, etc. Since none of these single factor has been always related to the presence of left atrial thrombus, related risk factors to left atrial thrombosis were studied in patients with mitral stenosis using chi square test. We had operated on 191 cases of mitral valvular heart disease from Jan. 1978 to June 1981 at Severance Hospital, Yunsei University College of Medicine. The left atrial thrombi were present in 41 cases among 191 cases of mitral valvular heart disease and it was present in 31 cases among 89 cases of pure mitral stenosis. Only 10 cases among 74 cases of mitral stenoregurgitation had left atrlal thrombi, whereas no left atrlal thrombus was found in patients with pure mitral regurgitation. Related risk factors studied herein were sex, episodes of congestive heart failure, atrial fibrillation, pulmonary capillary wedge pressure, mitral valve area calculated by Gorlin and Gorlin`s formula cardiac output and left atrial dimension by echocardiogram. In this study presence of atrial fibrillation was deemed to be one of the most potential risk factors and other factors of age, duration of symptoms, episode of embolization, calclfication of mitral valve, associated aortic and tricuspid valve disease, ejection fraction of left ventricle by cineangiocardiogram and echocardiogram were not significantly related to the presence of left atrlal thrombi in a statistical viewpoint.

• 열처리공학회지
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• 제23권1호
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• pp.23-28
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• 2010

The cylindrical magnetron sputtering has not been widely used, although this system is useful for only certain types of applications such as fiber coatings. This paper presents electrode configurations which improved the complicacy of the target assembly by using the positive voltage power supply. It is a modified type which has a target constructed with a large cylindrical part, a conical part and a small cylindrical part. When positive voltage was applied to an anode, a stable glow discharge was established and a high deposition rate was obtained. The substrate bias current was monitored to estimate the effect of ion bombardment. As a result, it was found that the substrate current was large. With cylindrical and conical cathode magnetron sputter deposition on the surface of the substrate to prevent re-sputtering, ion impact because it can increase the effectiveness with excellent ductility and adhesion of Ti film deposition can be obtained. We board at the front end of the ground resistance of $5\;k{\Omega}$ attached to the substrate potential can be controlled easily, and Ti film deposition with excellent adhesion can be obtained. Microstructure and morphology of Ti films deposited on pure Cu wires were investigated by scanning electron microscopy in relation to preparation conditions. High level ion bombardment was found to be effective in obtaining a good adhesion for Cu wire coatings.

• Journal of Microbiology and Biotechnology
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• 제25권6호
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• pp.893-902
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• 2015

Various Lactobacillus reuteri strains were screened for the ability to convert glycerol to 1,3-propanediol (1,3-PDO) in a glycerol-glucose co-fermentation. Only L. reuteri DSM 20016, a well-known probiotic, was able to efficiently carry out this bioconversion. Several process strategies were employed to improve this process. Co²⁺ addition to the fermentation medium, led to a high product titer (46 g/l) of 1,3-PDO and to improved biomass synthesis. L. reuteri DSM 20016 produced also ca. 3 µg/g of cell dry weight of vitamin B₁₂, conferring an economic value to the biomass produced in the process. Incidentally, we found that L. reuteri displays the highest resistance to Co²⁺ ions ever reported for a microorganism. Two waste materials (crude glycerol from biodiesel industry and spruce hydrolysate from paper industry) alone or in combination were used as feedstocks for the production of 1,3-PDO by L. reuteri DSM 20016. Crude glycerol was efficiently converted into 1,3-PDO although with a lower titer than pure glycerol (33.3 vs. 40.7 g/l). Compared with the fermentation carried out with pure substrates, the 1,3-PDO produced was significantly lower (40.7 vs. 24.2 g/l) using cellulosic hydrolysate and crude glycerol, but strong increases of the maximal biomass produced (2.9 vs 4.3 g/l CDW) and of the glucose consumption rate were found. The results of this study lay the foundation for further investigations to exploit the biotechnological potential of L. reuteri DSM 20016 to produce 1,3-PDO and vitamin B₁₂ using industry byproducts.

• 대한환경공학회지
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• 제37권11호
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• pp.597-606
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• 2015

KOH가 용해된 메탄올 및 에탄올 용액의 탄산화를 통해 Potassium methyl carbonate (PMC) 및 Potassium ethyl carbonate (PEC) 침전물을 합성하여 $CO_2$를 고정화하고 침전물의 특성 연구를 수행하였다. PMC 및 PEC는 $CO_2$의 화학 흡수 반응에 의해 고체 침전물로 합성되고 이를 위해 소비된 $CO_2$양은 각 이론 값의 97.90% 및 99.58%이며 탄산화 중 상당량의 물리 흡수도 일어난다. 합성된 침전물은 PMC 및 PEC와 $KHCO_3$의 중량 비율이 약 5:5 및 8:2인 혼합물이며 침전물들은 물에 용해되어 알코올이 재생되고 최종 $KHCO_3$가 회수됨에 따라 본 공정은 효율적인 하나의 CCS 또는 CCU 기술로 활용될 가능성이 있다.

• Korean Chemical Engineering Research
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• 제48권1호
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• pp.93-97
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• 2010

본 연구에서는 수정된 T-history 법을 사용하여 백신 또는 의약품들의 수송 시 냉매로 사용될 수 있는 $0{\sim}15^{\circ}C$의 상전이 온도를 갖는 유기 상전이 소재들과 이중 두 물질의 혼합물들의 열용량, 잠열, 비열과 같은 열 물성을 측정하였다. 순수한 파라핀들을 측정한 결과, 각 물질들의 상전이 온도를 고려하여 최적의 냉각 속도를 유지하며 측정을 하는 것이 열물성의 신뢰성을 향상시킬 수 있음을 알 수 있었고, 특히 혼합물의 열 물성 측정에 적용할 경우, 수정된 T-history 법의 사용은 기존의 DSC 분석에 사용하는 시료의 양이 소량이므로 유발될 수 있는 결과의 부정확성 등의 문제점을 해결하는데 기여할 수 있음을 알 수 있었다.

• Biomolecules & Therapeutics
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• 제22권4호
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• pp.328-333
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• 2014

Vitiligo is a pigmentary disorder induced by a loss of melanocytes. In addition to replacement of pure melanocytes, cocultures of melanocytes with keratinocytes have been used to improve the repigmentation outcome in vitiligo treatment. We previously identified by in vitro studies, that adipose-derived stem cells (ADSCs) could be a potential substitute for keratinocytes in cocultures with melanocytes. In this study, the efficacy of pigmentation including durability of grafted melanocytes and short-term safety was examined in the nude mouse and Sprague-Dawley rat after grafting of primary cultured human melanocytes, with or without different ratios of primary cultured human ADSCs. Simultaneous grafting of melanocytes and ADSCs, which were separately cultured and mixed on grafting at the ratios of 1:1, 1:2, or 1:3, showed better efficacy than that of pure melanocytes. Grafting of melanocytes cocultured with ADSCs resulted in a similar outcome as the grafting of cell mixtures. Skin pigmentation by melanocytes : ADSCs at the ratios of 1:1 and 1:2 was better than at 1:3. No significant difference was observed between the 1-week and 2-week durations in coculturing. Time-course microscopic examination showed that the grafted melanocytes remained a little longer than 6-week post-grafting. No inflammatory cell infiltration was observed in the grafted skin and no melanocytes were detectable in other organs. Collectively, grafting of melanocytes and ADSCs was equally safe and more effective than grafting of melanocytes alone. Despite the absence of significant differences in efficacy between the group of 1:1 and that of 1:2 ratio, 1:2 ratio for 1-week coculturing may be better for clinical use from the cost-benefit viewpoint.