동형 모더나이트 상에서 일산화탄소 산화반응에 대한 속도론

정명수,이창용,최고열,하백현 漢陽大學校 環境科學硏究所 1989 環境科學論文集 Vol.10 No.-

모더나이트에 동을 이온교환 및 담지시킨 후 환원·산화 처리를 하여 동의 상태를 변화시킨 촉매에 대해 일산화탄소 산화반응의 속도론적인 고찰을 행하였다. 이온교환 촉매나 담지촉매 모두 동의 상태와는 관계없이 일산화탄소에 관한 반응차수는 1차이고 산소에 관한 반응차수는 0차였다. 이온교환 촉매의 경우는 수소로 환원시켜 동이 금속상태로 존재할때와 이를 재산화시켜 산화동 상태로 존재할때는 활성화에너지가 각각 16.4 및 20.3으로 비교적 큰 값을 나타냈으나 동의 담지촉매의 경우는 동이 금속일 때나 산화물 상태 모두 12∼13kcal/mole로 비슷한 값을 나타냈으며 이온교환 촉매보다 상당히 감소함을 알 수 있었다. 이와 같은 결과는 이온교환 촉매의 경우는 동이 제올라이트내부에 대부분 존재하는 반면, 담지촉매의 경우는 제올라이트 결정 표면에 존재하기 때문에 활성을 증가시키는 것으로 생각된다. Kinetics of oxidation of carbon monoxide over copper mordenite was carried out at the temperature range between 373K-443K in the micro-catalytic reactor. The experimental results indicated that the reaction order, with respect to carbon monoxide and oxygen was first and zero order respectively, regardless of the valence states such as copper metal, copper ion and copper oxide on the mordenite. The activation energy for metal-copper mordenite which is obtained by the ion-exchange revealed 20kcal/mol. But if this was reoxidized under the oxygen it decreased to 16.6kcal/mol. The activation energy of metal-copper mordenite which was obtained by impregnation and its reoxidized one under the oxygen were 12.2kcal/mol and 13.3kcal/mol respectively.

고분자 전해질형 연료전지에서 Hot Pressing 조건의 영향

이태희,이승재,조원일,노용우,고영태,최경환 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1

고분자 전해질형 연료전지에서 고분자막/전극 어셈블리를 hot pressing 조건을 달리하여 제조하고 그 성능을 반응면적 5㎠인 단위전지에서 측정하였다. 전지의 성능은 고분자막과 전극간의 접합이 가능한 온도 범위에서 hot pressing온도가 낮을수록, hat Pressing 압력이 높을수록 향상되었다. 즉, 고분자 전해질형 연료전지의 성능은 고분자 전해질 내의 수분 함량 증가, 고분자막/전극간 접촉저항 감소 및 얇은 고분자막을 사용한 전해질의 이온저항 감소 등으로 향상시킬 수 있었다. For a proton exchange membrane fuel cell, membrane and electrode assemblies were fabricated by different hot pressing conditions and those performances were observed in a unit cell having 5 ㎠ active electrode area. The cell performance increased with lower hot pressing temperature in the range of temperature having intimate contact between membrane and electrodes and with higher hot pressing pressure. Namely, the performance of proton exchange membrane fuel cell could be raised with higher water content in the membrane, with lower contact resistance between membrane and electrodes and with lower ion resistance of the electrolyte using thinner membrane.

Weighing similarity against functionality to evaluate dung beetle species candidates for taxon substitution using an individual-based model

Jung-Wook Kho,Jung-Wook Kho,Joo-Young Kim,Do-Hun Gook,Hyunjoong Kim,Soowan Kim,Doo-Hyung Lee 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.04

<i>Gastrodia elata</i> Ameliorates High-Fructose Diet-Induced Lipid Metabolism and Endothelial Dysfunction

Kho, Min Chul,Lee, Yun Jung,Cha, Jeong Dan,Choi, Kyung Min,Kang, Dae Gill,Lee, Ho Sub Hindawi Publishing Corporation 2014 Evidence-based Complementary and Alternative Medic Vol.2014 No.-

<P>Overconsumption of fructose results in dyslipidemia, hypertension, and impaired glucose tolerance, which have documented correlation with metabolic syndrome. <I>Gastrodia elata</I>, a widely used traditional herbal medicine, was reported with anti-inflammatory and antidiabetes activities. Thus, this study examined whether ethanol extract of <I>Gastrodia elata</I> Blume (EGB) attenuate lipid metabolism and endothelial dysfunction in a high-fructose (HF) diet animal model. Rats were fed the 65% HF diet with/without EGB 100 mg/kg/day for 8 weeks. Treatment with EGB significantly suppressed the increments of epididymal fat weight, blood pressure, plasma triglyceride, total cholesterol levels, and oral glucose tolerance, respectively. In addition, EGB markedly prevented increase of adipocyte size and hepatic accumulation of triglycerides. EGB ameliorated endothelial dysfunction by downregulation of endothelin-1 (ET-1) and adhesion molecules in the aorta. Moreover, EGB significantly recovered the impairment of vasorelaxation to acetylcholine and levels of endothelial nitric oxide synthase (eNOS) expression and induced markedly upregulation of phosphorylation AMP-activated protein kinase (AMPK)<I><I>α</I></I> in the liver, muscle, and fat. These results indicate that EGB ameliorates dyslipidemia, hypertension, and insulin resistance as well as impaired vascular endothelial function in HF diet rats. Taken together, EGB may be a beneficial therapeutic approach for metabolic syndrome.</P>

Cancelable fingerprint template design with randomized non-negative least squares

Kho, Jun Beom,Kim, Jaihie,Kim, Ig-Jae,Teoh, Andrew B.J. Elsevier 2019 Pattern recognition Vol.91 No.-

<P><B>Abstract</B></P> <P>Although biometrics is considered more competent than password-based or token-based approach in identity management, biometric templates are vulnerable to adversary attacks that may lead to irreversible identity loss. One of the promising remedies for biometric template protection is cancelable biometrics. In this paper, a novel binary cancelable fingerprint template design based on Partial Local Structure (PLS) descriptor and Permutated Randomized Non-Negative Least Square (PR-NNLS) is proposed. The PLS descriptor is an alignment-free minutia descriptor, which is conceived to be coupled with the PR-NNLS to derive a binary protected fingerprint template that satisfies non-invertibility, unlinkability, cancelability and performance criteria. The PR-NNLS formulation is unique in such a way that the noninvertible transformation is applied to the PLS descriptor dictionary instead of applying it to the minutiae descriptor, which often invites performance deterioration. The evaluations have been carried out with five subsets from FVC 2002 and 2004 databases where the proposed method is attested to fulfill the aforementioned four template protection criteria. We also analyze four privacy and security attacks targeted to cancelable biometrics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel alignment-free minutiae descriptor that based on Partial Local Structure (PLS) is proposed, which is beneficial to generate discriminative and compact binary cancelable fingerprint template. </LI> <LI> The non-invertible transformation of the PLS descriptor is formulated as a problem of solving randomized Non-Negative Least Square (R-NNLS) optimization problem, which is unique in a way to get rid of the performance deterioration issue when applying the non-invertible transformation directly to the minutiae descriptor for the fingerprint template protection. </LI> <LI> The revocability and the unlinkability traits of the proposed method are enabled by introducing a permutation mechanism to the R-NNLS. </LI> <LI> The proposed method is rigorously evaluated with five benchmark datasets, and four security and privacy analyses are also carried out. </LI> </UL> </P>

Administration of placenta-derived mesenchymal stem cells counteracts a delayed anergic state following a transient induction of endogenous neurogenesis activity after global cerebral ischemia

Kho, A Ra,Kim, Ok Joon,Jeong, Jeong Hyun,Yu, Ji Min,Kim, Hye Sun,Choi, Bo Young,Suh, Sang Won,Chung, Tae Nyoung Elsevier 2018 Brain Research Vol.1689 No.-

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Global cerebral ischemia (GCI) is a major obstacle for cardiac arrest survival. Recent studies have suggested the possibility of mesenchymal stem cell (MSC) as a novel therapeutic option for GCI, but these results were limited to the neuroprotective effects of MSCs. Therefore, we aimed to investigate specific characteristics of neurogenesis after transient GCI, and to assess the effect of MSC on these characteristics.</P> <P><B>Methods</B></P> <P>Adult male Sprague–Dawley rats were subjected to 7 min of transient GCI and randomized into 7 groups: baseline, MSC, and control administered groups, to be analyzed at 2, 3, and 4 weeks after GCI, respectively. The same interventions were repeated for sham operated animals. Rats were euthanized at the designated time after GCI.</P> <P><B>Results</B></P> <P>A comparison of GCI and sham groups without MSC treatment, showed that the counts of bromodeoxyuridine (BrdU)- and doublecortin (DCX)-positive cells were significantly increased in the GCI group at 1 week after insult, but the trend was reversed at 3 weeks after insult. The counts of BrdU-, Ki67- and DCX-positive cells and the intensity of zinc translocator 3 (ZnT3) were all significantly higher in the MSC-treated group than those in the control group at 3 weeks after GCI. The count of NeuN-positive cells in the hippocampus was significantly increased in the MSC group at 4 weeks after GCI.</P> <P><B>Conclusions</B></P> <P>GCI induces transient neurogenesis, followed by an anergic state. MSC may counteract this anergy of neurogenesis and result in an increase in intact neurons in later stages.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Neurogenesis increased after global cerebral ischemia but decreased soon. </LI> <LI> MSC administration counteracted the decrease of neurogenesis activity. </LI> <LI> Counteraction of MSC to anergy of neurogenesis resulted in more intact neurons. </LI> <LI> Effect of MSC on neurogenesis activity is consistent with ZnT3 expression. </LI> </UL> </P>

Oral Medicine in Korea, Can We Become a Global Leader?

Kho, Hong-Seop Korean Academy of Orofacial Pain and Oral Medicine 2015 Journal of Oral Medicine and Pain Vol.40 No.1

Effects of Protocatechuic Acid (PCA) on Global Cerebral Ischemia-Induced Hippocampal Neuronal Death

Kho, A Ra,Choi, Bo Young,Lee, Song Hee,Hong, Dae Ki,Lee, Sang Hwon,Jeong, Jeong Hyun,Park, Kyoung-Ha,Song, Hong Ki,Choi, Hui Chul,Suh, Sang Won MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.5

<P>Global cerebral ischemia (GCI) is one of the main causes of hippocampal neuronal death. Ischemic damage can be rescued by early blood reperfusion. However, under some circumstances reperfusion itself can trigger a cell death process that is initiated by the reintroduction of blood, followed by the production of superoxide, a blood–brain barrier (BBB) disruption and microglial activation. Protocatechuic acid (PCA) is a major metabolite of the antioxidant polyphenols, which have been discovered in green tea. PCA has been shown to have antioxidant effects on healthy cells and anti-proliferative effects on tumor cells. To test whether PCA can prevent ischemia-induced hippocampal neuronal death, rats were injected with PCA (30 mg/kg/day) per oral (p.o) for one week after global ischemia. To evaluate degenerating neurons, oxidative stress, microglial activation and BBB disruption, we performed Fluoro-Jade B (FJB), 4-hydroxynonenal (4HNE), CD11b, GFAP and IgG staining. In the present study, we found that PCA significantly decreased degenerating neuronal cell death, oxidative stress, microglial activation, astrocyte activation and BBB disruption compared with the vehicle-treated group after ischemia. In addition, an ischemia-induced reduction in glutathione (GSH) concentration in hippocampal neurons was recovered by PCA administration. Therefore, the administration of PCA may be further investigated as a promising tool for decreasing hippocampal neuronal death after global cerebral ischemia.</P>

Agora and Its Possibilities in James Joyce’s “Wandering Rocks”

Kho, Younghee 미래영어영문학회 2021 영어영문학 Vol.26 No.1

Reviving and representing the concept of agora, a central space for the politics, economy, and religion of ancient Greek city-states, this paper claims that Joyce in Dubliners and Ulysses evaluates the limitations and possibilities of Ireland as an emerging nation through the citizens’ interactions in agora. Focusing on this public space’s role for communication, the paper pays attention to the kinds and characters of communication especially in “Eveline” and “Wandering Rocks.” In the former story, Eveline is occupied in her uncommunicable concern of whether or not she has to leave Ireland, yet her agoraphobia ultimately ends her communication with others, especially with Frank who she regards as a possible savior from her stifling situation. The citizens in “Wandering Rocks” do not show such physical symptoms of agoraphobia as Eveline; however, their consciousness and communication still expose what obstructs themselves from intellectual development. The pretentious and uncharitable attitude of Dubliners, perhaps except for foreign Bloom and female Molly, marks their communication everywhere and develops a false community in this episode. Molly and Bloom, in contrast, open up possibilities for building an ideal community through the act of charity, which is particularly emphasized in this episode.

Antioxidant Capacity of Fresh and Processed Fruit Bodies and Mycelium of Auricularia auricula-judae (Fr.) Qu$\acute{e}$l

Kho, Y.S.,Vikineswary, S.,Abdullah, Noorlidah,Kuppusamy, U.R.,Oh, H.I. The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.1

Auricularia auricula-judae is currently grown in Malaysia. In the present study, the methanolic extracts from fruit bodies (fresh, oven-dried, and freeze-dried) and mycelium of A. auricula-judae were evaluated for their antioxidant capacities based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The total phenolic content in the extracts were also measured. The extract of freeze-dried fruit bodies of A. auricula-judae had potent DPPH free radical scavenging activity with a 50% effective concentration of 2.87 mg/mL, whereas the FRAP value of A. auricula-judae mycelium was $5.22\;{\mu}mol$ of $FeSO_4{\cdot}7H_2O$ equivalents/g of mycelium sample. Further, a positive correlation ($R^2\;=\0.7668$) between FRAP level of A. auricula-judae extracts and the total phenolic contents was observed. Thus the method of processing of fresh fruit bodies had an effect on the antioxidant potential of A. auricula-judae.