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Fabrication of Pre-Exfoliated Clay Masterbatch via Exfoliation-Adsorption of Polystyrene Nanobeads
Khvan, Svetlana,Kim, Jun-Kyung,Lee, Sang-Soo The Polymer Society of Korea 2007 Macromolecular Research Vol.15 No.1
The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.
( Khvan Ekaterina ),( Yemi Kim ),( Ji Youn Kim ),( Myung Rae Kim ),( Sung O Kim ),( Sun Jong Kim ) 한국조직공학·재생의학회 2012 조직공학과 재생의학 Vol.9 No.5
The objective of this study was to evaluate the feasibility of a new xenograft material Ti-Oss (Chiyewon, Guri, Korea) by investigating the degree of new bone formation compared with that of other commonly used xenografts Bio-Oss(R)(Geistlich Pharma AG, Wolhusen, Switzerland) and OCS-B(R)(NIBEC, Seoul, Korea). Forty rats were used in the study. The animals were randomly allocated into four groups of 10 animals each. The Group 1`s calvarial defect was untreated, Group 2`s defect was filled with Bio-Oss(R)(Geistlich Pharma AG), Group 3`s defect was filled with OCS-B(R)(NIBEC), and Group 4`s defect was filled with Ti-Oss(R)(Chiyewon). The animals were sacrificed at 2 (n=5) and 8 (n=5) weeks for histomorphometric analysis. The histomorphometric analysis showed the statistically significant difference between the groups with a mean bone formation of 0.35±0.10 mm (8.75%) for Bio-Oss(R) group, 0.19±0.04 mm (4.75%) for OCS-B(R) group, 0.26±0.04 mm (6.5%) for Ti-Oss(R) group at 2 week healing period. At 8 weeks, a mean bone formation of 1.93±0.18 mm (48.25%) for Bio-Oss(R) group, 1.12±0.11 mm (28%) for OCS-B(R) group, 1.50±0.28 mm (37.5%) for Ti-Oss(R) group showed the statistically significant difference (p < 0.05). Within the limits of present study, it was concluded that the newly investigated xenograft, Ti-Oss(R), revealed biocompatibility and effectiveness in bone formation. Ti-Oss(R) could be proposed as a potential material for filling osseous defects. Further clinical trials of the new bovine xenograft Ti-Oss(R) are needed for an understanding its relevance in dentistry.
Hybrid Deinterlacing Algorithm with Motion Vector Smoothing
Khvan Dmitriy,Jeon Gwanggil,Jeong Jechang 한국방송공학회 2012 한국방송공학회 학술발표대회 논문집 Vol.2012 No.7
In this paper we propose a new deinterlacing method with block classification and motion vector smoothing. The proposed method classifies a block, then depending on the region it belongs to, the motion estimation or line averaging is applied. To classify a block its variance is calculated. Then, for those blocks that belong to simple non-texture region the line averaging is done while motion estimation is applied to complex region. The motion vector field is smoothed using median filter what yields more accurate interpolation. In the experiments for the subjective evaluation, the proposed method bas shown satisfying results in terms of computation time consumption and peak signal-to-noise ratio. Due to the simplicity of the algorithm computation time was drastically decreased.
Fast Scene Change Detection Algorithm
Khvan, Dmitriy,Ng, Teck Sheng,Jeong, Jechang 한국방송·미디어공학회 2012 한국방송공학회 학술발표대회 논문집 Vol.2012 No.11
In this paper, we propose a new fast algorithm for effective scene change detection. The proposed algorithm exploits Otsu threshold matching technique, which was proposed earlier. In this method, the current and the reference frames are divided into square blocks of particular size. After doing so, the pixel histogram of each block is generated. According to Otsu method, every histogram distribution is assumed to be bimodal, i.e. pixel distribution can be divided into two groups, based on within-group variance value. The pixel value that minimizes the within-group variance is said to be Otsu threshold. After Otsu threshold is found, the same procedure is performed at the reference frame. If the difference between Otsu threshold of a block in the current frame and co-located block in the reference frame is larger than predefined threshold, then a scene change between those two blocks is detected.
( Marina Khvan ),( Nazym Nigmatullina ),( Saltanat Rakhimzhanova ),( Samat Issakov ),( Venera Altynova ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Introduction: Hepatitis C virus (HCV) infection is an important co-morbidity in patients after kidney transplantation (KT) affecting patient and graft survival. In the era of Direct Acting Antiviral (DAA) drugs the current standards of management strongly suggest to treat HCV positive patient with end-stage renal disease (ESRD) before KT. However, in the conditions where this treatment is not available, KT remains the only lifesaving option for children with ESRD who is not able to sustain on dialysis any longer. Aim: Currently, there is limited data available about outcomes of pediatric patients with HCV after kidney transplantation. We studied the prevalence, clinical profile and outcome of HCV infection in KT pediatric recipients (KTPR) in Kazakhstan for the first time after the launching the National Pediatric KT Program in 2012. Methods: We studied pediatric patients who underwent KT from January 2012 to December 2018 at the Department of Nephrology, Dialysis and Transplantation, National Research Center of Mother and Child Health, University Medical Center, Nur-Sultan. HCV infection was defined as a positive anti-HCV antibody and/or HCV RNA PCR positivity. Control group included KTPRs with no evidence of HCV or hepatitis B virus (HBV) infection. Results: A total of 73 KTPRs were included. The mean age was 10.6 ± 4.5 years, male:female ratio was 1:1 and mean duration of post-transplant follow-up was 32 months. 9 patients (12%) had evidence of HCV infection. All HCV-positive patients underwent KT before DAAs were available in the country. Among them 4 patients were treated with interferon before KT, 4 patients had HCV infection by the time of KT and 1 patient developed de-novo HCV infection after KT. Although there was no statistical significant difference in patient survival (logrank P=0.82) and graft survival (log-rank P=0.416) between HCV-positive group and controls, the only death in HCV group was registered in the patient who had de-novo HCV infection after KT. 2 patients who were treated from HCV infection before KT lost their kidney grafts and returned on dialysis. Among 4 patients with persistent HCV infection by the time of KT, 2 were successfully treated with DAAs 5 years after KT without any side effects or worsening of graft function. 2 KTPRs still have chronic HCV infection Stage 0 - 1 with low viral load, normal liver function tests and normal kidney graft function over the 6 years after KT. Conclusions: In our cohort HCV-positive KTPRs did not have any difference in patient and graft survival comparing to KTPRs without HCV infection. The worst outcome had patient with de-novo developed HCV infection after KT. HCV treatment with DAA after KT was successful without deterioration of kidney graft function. Limitation: low number of HCV-positive KTPRs.
Large scale vertical implantation of crystalline titania nanotube arrays
Svetlana V. Khvan,이상수,홍성철,김준경 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.6
We present simple method to fabricate large scale TiO2 nanotube arrays of a few tens micrometers length perpendicularly implanted on transparent electroconducting glass substrate. The thickness and morphology of the titania nanotube arrays layer can be easily tuned, enabling designing the optimal architecture of the nanostructured titania film for diverse applications including dyesensitized solar cell.
Chaimun Lee(이채문),Khvan Lyudmila Borisovna(황류드밀라 보리소브나) 부산대학교 한국민족문화연구소 2020 한국민족문화 Vol.74 No.-
본 연구는 캄차카와 사할린의 한인 이민자들을 디아스포라적 관점에서 비교 및 분석하는 것을 목표로 하고 있다. 연구방법에서는 캄차카의 엘리조보와 부산 정관의 사할린 영주귀국자들을 대상으로 한 현지조사에서 수집된 구술을 연구자료로 하여 두 지역 한인 디아스포라의 초국가적 관행을 분석한다. 구체적으로 본 논문에서는 거주국으로부터의 소외, 혈연국의 차이, 모국에 대한 귀향욕구 및 유교적 관습 등의 초국가주의적 관행을 중심으로 연구를 진행하였다. 연구의 구체적인 결과에 따르면, 캄차카 거주 북한이주민의 혈연국인 북한의 정치체제의 폐쇄성 및 최근 한국과의 밀접한 관계 등의 영향으로 이들 이주민들은 정체적 혼란을 경험하고 있는 것으로 나타나고 있지만, 그럼에도 불구하고 이들의 초국가적 지향성은 여전히 존재하고 있음을 보여주고 있다. 아마도 이런 결과는 캄차카와 사할린 거주 북한이주민과 사할린 영주귀국자들간에 존재하는 혈연국에 있어서의 차이 때문으로 판단되지만, 그럼에도 불구하고 이들 한인 이산민들의 정체성 형성에 초국가주의는 중요한 역할을 하고 있는 것으로 나타난다. 사할린섬과 캄차카 반도에서 코리안 디아스포라에 대한 러시아인들의 차별, 그리고 이들 한인들의 현지에서의 소외는 이들로 하여금 더욱 종족 정체성을 구축하는데 중요한 역할을 하였다. 또한 사할린과 캄차카에서 거주하는 한인들은 거주하는 지역에 상관없이 여전히 모국에 대한 귀환 욕구가 매우 강한 것으로 나타나고 있다. 마지막으로 본 연구에서 유교적 관습에 따른 장례식이나 제사 및 환갑 등의 전통적인 한국 문화는 캄차카와 사할린의 한인들로 하여금 끊임없이 모국과의 연계성을 더욱 강화시키는 역할을 하는 것으로 드러나고 있다. The goal of this study is to analyze diasporic aspects of North Korean migrants in Kamchatka, in comparison with those of Korean diaspora in Sakhalin. In particular, using narratives of ethnic Koreans obtained in two field surveys in Elizovo in Kamchatka, Russia and Jeonggwan in Busan, South Korea, this study tries to compare transnational practices of those Korean diaspora both in Sakhalin and Kamchatka, Russia. In this paper four transnational practices including alienation from the host countries, differences in kin-states, desire for an eventual return to the homeland, and Confucian ethics were analyzed and compared between those Korean immigrants in both residential areas. According to the results of the study, the closure of the political system in North Korea and the kin-state of Koreans living in the Kamchatka Peninsula caused the North Korean diaspora to confuse their feelings about their home country, but those could not weaken transnationalism among them. It may be due to the fact that South and North Korea, homelands for two Korean diaspora in Sakhalin and Kamchatka, are different in their political or economic system or structure but identical in their cultural and spiritual roots. Russian discrimination against the Korean diaspora in Sakhalin Island and the Kamchatka Peninsula as well as subsequent alienation felt by these Koreans have played an important role in strengthening their ethnic identity. In addition, Koreans living in Sakhalin and Kamchatka still have a strong desire to return to their home countries regardless of where they live. Finally, this study shows that traditional Confucian Korean customs, such as funerals, rituals, and sixtieth birthdays, lead those ethnic Koreans in the Russian Far East to strengthen their connection with their homeland. All in all, this study illustrates that transnational practices of ethnic Koreans exert a similar influence on the reconstruction of diasporic identities, even though there are differences in their kin-states.