• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.37.1-37.1
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• 2017

Since the seminal work of Perrin, physicists have understood in the context of kinetic theory how ink slowly diffuses in a glass of water. The fluctuations of the stochastic forces acting on water molecules drive the diffusion of the ink in the fluid. This is the archetype of a process described by the so-called fluctuation-dissipation theorem, which universally relates the rate of diffusion to the power spectrum of the fluctuating forces. For stars in galaxies, a similar process occurs but with two significant differences, due to the long-range nature of the gravitational interaction: (i) for the diffusion to be effective, stars need to resonate, i.e. present commensurable frequencies, otherwise they only follow the orbit imposed by their mean field; (ii) the amplitudes of the induced fluctuating forces are significantly boosted by collective effects, i.e. by the fact that, because of self-gravity, each star generates a wake in its neighbours. In the expanding universe, an overdense perturbation passing a critical threshold will collapse onto itself and, through violent relaxation and mergers, rapidly converge towards a stationary, phase-mixed and highly symmetric state, with a partially frozen orbital structure. The object is then locked in a quasi-stationary state imposed by its mean gravitational field. Of particular interests are strongly responsive colder systems which, given time and kicks, find the opportunity to significantly reshuffle their orbital structure towards more likely configurations. This presentation aims to explain this long-term reshuffling called gravity-driven secular evolution on cosmic timescales, described by extended kinetic theory. I will illustrate this with radial migration, disc thickening and the stellar cluster in the galactic centre.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.261-273
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• 2017

The control of the deformative behaviour of pre-stressed concrete roof elements for a satisfactory service performance is a main issue of their structural design. Slender light-weight wing-shaped roof elements, typical of the European heritage, are particularly sensitive to this problem. The paper presents the results of deformation measurements during storage and of both torsional-flexural and purely flexural load tests carried out on a full-scale 40.5 m long innovative wing-shaped roof element. An element-based simplified integral procedure that de-couples the evolution of the deflection profile with the progressive shortening of the beam is adopted to catch the experimental visco-elastic behaviour of the element and the predictions are compared with normative close-form solutions. A linear 3D fem model is developed to investigate the torsional-flexural behaviour of the member. A mechanical non-linear beam model is used to predict the purely flexural behaviour of the roof member in the pre- and post-cracking phases and to validate the loss prediction of the adopted procedure. Both experimental and numerical results highlight that the adopted analysis method is viable and sound for an accurate simulation of the service behaviour of precast roof elements.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.833-837
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• 2004

DeniLite$^{TM}$ laccase immobilized platinum electrode was used for amperometric detection of hydroquinone (HQ) and homogentisic acid (HGA) by means of substrate recycling. In case of HQ, the obtained sensitivity is 280 nA/ ${\mu}$M with linear range of 0.2-35 ${\mu}$M ($r^2$ = 0.998) and detection limit (S/N = 3) of 50 nM. This high sensitivity can be attributed to chemical amplification due to the cycling of the substrate caused by enzymatic oxidation and following electrochemical regeneration. In case of HGA, the obtained sensitivity is 53 nA/ ${\mu}$M with linear range of 1-50 $[\mu}M\;(r^2$ = 0.999) and detection limit of 0.3 ${\mu}$M. The response times ($t_{90%}$) are about 2 seconds for the two substrates and the long-term stability is 60 days for HQ and around 40-50 days for HGA with retaining 80% of initial activities. The very fast response and the durable long-term stability are the principal advantages of this sensor. pH studies show that optimal pH of the sensor for HQ is 6.0 and that for HGA is 4.5-5.0. This shift of optimal pH towards acidic range for HGA can be attributed to the balance between enzyme activity and accessibility of the substrate to the active site of the enzyme.

• The Journal of Korean Medical History
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• v.26 no.1
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• pp.97-106
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• 2013

What is the fundamental cause of the broader gap between East and West medicine? This is a very long story that began in the late Renaissance and still continues today. Why it took so long time from the end of the XIIth century when acupuncture was firt imported to Europe to XX century when it was finally settled in France? We present three cases which caused the delayed establishment : A "blisters" article from Diderot and D'Alembert in the eighteenth century, the practice of acupuncture by Dr. Berlioz in Paris in early 19th century, and the reception of the works of Georges Soulie de Morant in France in the 1930's. We attempt to show the misunderstanding that has always prevailed between the East and West medicines because of different viewpoint : the West has not understood the richness and subtlety of the approach of East asian thought and wanted to "align" the Asian medical modality to west medicine with inappropriate and insufficient "experiments" without enough explanation of the principles and philosophical backgrounds. It was not the matter of technology but the mutual incomprehension of history and culture.

• Journal of Species Research
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• v.8 no.3
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• pp.259-267
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• 2019

Five free-living nematode species belonging to the order of Rhabditida are described for the first time in Korea. Two unrecorded species of Rhabditidae, Cruznema tripartitum (Linston, 1906) Zullini, 1982, and Poikilolaimus oxycerca de Man, 1895, and one species of Peloderidae, Pelodera strongyloides Schneider, 1860, were collected in Korea. C. tripartitum has nine pairs of genital papillae arranged in 2+2+1+4 differently from similar species of C. scarabaeum which has ten genital papillae arranged in 2+1+4+3. Poikilolaimus oxycerca has shorter tail (shorter than anal body diameter) compared to similar species of P. regenfussi which has longer tail(longer than anal body diameter). Pelodera strongyloides has shorter tail(1-1.5 times anal body diameters long) than P. punctata (4 anal body diameters long). Two unrecorded species of Panagrolaimidae, Panagrolaimus apicatus Schuurmans Stekhoven & Teunissen, 1938 and Panagrolaimus rigidus (Schneider, 1866) Thorne, 1937 were collected in Korea. P. apicatus has rounded and lower lip compared to similar species, P. margaretae Massey, 1964 which has finely pointed lip. P. rigidus has slender tail and lips rounded and flat barely separated when compared to similar species, P. subelongatus(Cobb, 1914) Thorne, 1937 which has plumper tail and lips are well separated.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.110-134
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• 2023

North Korea's development and deployment of nuclear weapons increases Pyongyang's diplomatic bargaining leverage. It is a strategic response to counteract the great expansion in US leverage with the collapse of the USSR. Post-Cold War American influence and hegemony is justified partly by claiming victory in successfully containing an allegedly imperialist Soviet Union. The US created and led formal and informal international institutions as part of its decades-long containment grand strategy against the USSR. The US now exploits these institutions to expedite US unilateral global preeminence. Third World regimes perceived as remnants of the Cold War era that resist accommodating to American demands are stereotyped as rogue states. Rogue regimes are criminal offenders who should be brought to justice, i.e. regime change is required. The initiation of summit diplomacy between US President Trump and North Korean leader Kim Jong-un occurred following the January 2018 Hawaiian ballistic missile false alarm. This event and its political consequences illustrate the efficacy of nuclear weapons as bargaining leverage for so-called rogue actors. North Korea is highly unlikely to surrender those weapons that were the instigation for the subsequent summit diplomacy that occurred. A broader, critical trend-focused strategic analysis is necessary to adopt a longer-term view of the on-going Korean nuclear crisis. The aim would be to conceptualize long-term policies that increase the probability that nuclear weapons capability becomes a largely irrelevant issue in interaction between Pyongyang, Seoul, Beijing and Washington.

• Journal of Animal Science and Technology
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• v.66 no.5
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• pp.1079-1082
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• 2024

Treponema pedis, a fastidious anaerobic spirochete, is one of the main pathogens involved in the development and progression of bovine digital dermatitis (BDD), a lameness-causing hoof infection in cattle. Here, the complete genome sequencing of T. pedis GNW45 isolated from a dairy cow infected with BDD, was presented. Libraries for long and short reads were sequenced using PacBioRSII and Illimuna HiSeqXTen platforms, respectively. De-novo assembly was done using the long reads, producing a circular contig, by which the short reads were aligned to generate a more accurate genome sequence. The genome has a total size of 3,077,465 base pairs, with 36.84% guanine-cytosine content. A total of 2,749 protein-coding sequences, seven ribosomal RNA's, and 45 transfer RNA's were annotated. Functional analysis revealed genes associated with pathogenicity and survivability in the complex pathobiome of BDD. This study provided novel insights into the survival and pathogenic mechanisms of T. pedis GNW45.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.10 no.2
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• pp.166-172
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• 2007

Purpose: It has recently been reported that de novo HBV infection following liver transplantation is caused by grafts from HBcAb positive donors, and this phenomenon has been observed in one third of the liver transplant patients in our center. Therefore, we investigated the presence of HBV virus DNA in liver tissues obtained from HBcAb positive donors to determine the mechanism by which de novo HBV infection occurs. Methods: This study was conducted on 6 patients that were HBsAg negative, HBsAb positive, and HBcAb positive who were donors for liver transplantation between November 1997 and November 1998 at Asan Medical Center. We isolated DNA from a portion of liver biopsy tissues that were obtained during the operation, and then identified the surface and core region of HBV DNA using nested PCR. In addition, four children who received liver grafts from these donors were monitored to determine if they became afflicted with non-HBV related diseases while receiving prophylaxis consisting of short-term HBIG treatment and long-term treatment with an antiviral agent. Results: The surface antigen region was identified in all 6 donors and the core antigen region was observed in 4 of the 6 donors. However, no episodes of de novo HBV infection with prophylaxis were observed. Conclusion: The results of this study support the results of previous studies, which indicated that HBV infection may be the main cause of de novo HBV infection in patients that receive HBsAb positive and HBcAb positive donor grafts.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5187-5194
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• 2014

Background: Numerous studies have suggested that selenium deficiency may be associated with an increased risk for several types of cancer, but few have focused on thyroid cancer. Materials and Methods: We examined the association between post-diagnostic fingernail selenium levels and differentiated thyroid cancer risk in a French Polynesian matched case-control study. Conditional logistic regression models were used to estimate odds ratios and 95% confidence intervals. Results: The median selenium concentration among controls was $0.76{\mu}g/g$. Significantly, we found no association between fingernail selenium levels and thyroid cancer risk after conditioning on year of birth and sex and additionally adjusting for date of birth (highest versus lowest quartile: odds-ratio=1.12, 95% confidence interval: 0.66-1.90; p-trend=0.30). After additional adjustment for other covariates, this association remained non-significant (p-trend=0.60). When restricting the analysis to thyroid cancer of 10 mm or more, selenium in nails was non-significantly positively linked to thyroid cancer risk (p-trend=0.09). Although no significant interaction was evidenced between iodine in nails and selenium in nails effect (p=0.70), a non-significant (p-trend =0.10) positive association between selenium and thyroid cancer risk was seen in patients with less than 3 ppm of iodine in nails. The highest fingernail selenium concentration in French Polynesia was in the Marquises Islands ($M=0.87{\mu}g/g$) and in the Tuamotu-Gambier Archipelago ($M=0.86{\mu}g/g$). Conclusions: Our results do not support, among individuals with sufficient levels of selenium, that greater long-term exposure to selenium may reduce thyroid cancer risk. Because these findings are based on post-diagnostic measures, studies with prediagnostic selenium are needed for corroboration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.626-631
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• 2019

The policy-making and technological development for the supply expansion of eco-friendly automobiles has been continuing, but the internal combustion engines still accounts for about 95%. Also, in order to meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is gradually increasing. This study is a basic study for the post-Euro-VI exhaust response of CNG buses, and it is to investigate the basic characteristics according to Pd substitution transition metal effect, catalyst volume effect and space velocity. A catalysts was prepared and tested using a model gas reactor. The NGOC catalyst with 3Pd exhibited the highest catalytic activity with 22% at $300^{\circ}C$, 48% at $350^{\circ}C$ and about 75% at $500^{\circ}C$. 3Co NGOC containing 3wt% of transition metal was excellent in oxidation ability, and it was small in size of 2nm, and the degree of catalyst dispersion was improved and de-NO/CO conversion was high. The volume of the NGOC-LNT-SCR catalyst system was optimal in the combination of 1.5+0.5+0.5 with a total score of 165, considering $de-CH_4/NOx$ performance and catalyst cost. For SV $14,000h^{-1}$, the $CH_4$ reduction performance was the highest at about 20%, while the SV $56,000h^{-1}$ was the lowest at about 5%. If the space velocity is small, the flow velocity decreases and the time remaining in the catalyst volume become long, so that the harmful gas was reduced.