Conceptual Study for Tissue-Regenerative Biodegradable Magnesium Implant Integrated with Nitric Oxide-Releasing Nanofi bers

Jin‑Kyung Jeon,Hyunseon Seo,Jimin Park,Soo Ji Son,Yeong Rim Kim,Eun Shil Kim,Jong Woong Park,Woong‑Gyo Jung,Hojeong Jeon,Yu‑Chan Kim,Hyun‑Kwang Seok,Jae Ho Shin,Myoung‑Ryul Ok 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4

The excessive initial corrosion rate of Mg is a critical limitation in the clinical application of biodegradable Mg implantsbecause the device loses its fi xation strength before the fractured bone heals. This study suggests a new approach to overcomethis hurdle by accelerating tissue regeneration instead of delaying the implant biodegradation. As angiogenesis is anessential process in early bone regeneration, a Mg implant coated with electrospun nanofi bers containing nitric oxide (NO),which physiologically promotes angiogenesis, is designed. The integrated device enables adjustable amounts of NO to bestored on the NO donor-conjugated nanofi ber coating, stably delivered, and released to the fractured bone tissue near theimplanted sites. An in vitro corrosion test reveals no adverse eff ect of the released NO on the corrosion behavior of the Mgimplant. Simultaneously, the optimal concentration level of NO released from the implant signifi cantly enhances tube networkformation of human umbilical vein endothelial cells without any cytotoxicity problem. This indicates that angiogenesis canbe accelerated by combining NO-releasing nanofi bers with a Mg implant. With its proven feasibility, the proposed approachcould be a novel solution for the initial stability problem of biodegradable Mg implants, leading to successful bone fi xation.

국내 무연탄용 순환유동층 Boiler의 Clinker생성에 관한 연구

전문택,김진호,김경남 三陟大學校 産業科學技術硏究所 2002 産業科學技術硏究論文集 Vol.7 No.1

The analysis of anthracite coal as fired basis and clinkers located on combustor, seal pot and cyclone to find out the reason why the bed materials agglomerated and resulted in clinkers were studied. It was one of the most serious problem in early period operating the Tonghae CFBC(Circulating Fluidized Bed Combustor). The proximate analysis, heat value analysis, ash fusion temperature analysis and size distribution analysis of coal & ash were studied using TGA, Bomb Calorimeter, Ash Fusibility Determination and Sieve Shaker. The chemical compositions and microstructure of raw material and clinker located on combustor, seal pot and cyclone were investigated by the scanning electron microscope(SEM) with an energy dispersive X-ray spectrometer(EDS), ICP-AES, X-ray diffractometer(XRD). The domestic anthracite coal had much fine size portion which could cause after burning. Furthermore domestic coal had higher ignition temperature and lower volatile matter portion than bituminous coal, which finally ended in low combustion velocity. So it is fundamental to lengthen the furnace residence time to reach complete combustion. And it is possible to use auxiliary fuel but its dependence is low for CFBS because combustion temperature is at around 800~850℃, which range is very lower than general fine size coal combustion type. Fine size coal could do after burning, so it could cause temperature rising at combustor upper region and clinker formation by means of fouling. The short residence time of fine size coal in furnace can bring out high content of unburned carbon in fly ash, so it is necessary to reduce the fine size coal content. Assembling the result of chemical composition analysis, crystal structure analysis and EDS analysis of clinker, we could conclude that calcium in limestone and iron in bed material did the main effect in agglomeration.

경식도 심초음파도의 Direct Planimetry를 이용하여 측정한 대동맥판 면적의 심박출량 및 좌심실 구출율의 변화에 따른 정확도

진승원,김종진,김희열,박지원,전두수,윤호중,박준철,노태호,채장성,김재형,홍순조,최규보 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.8

전자장치 냉각을 위한 수직수로에서의 열-사이펀 비등실험

전진석,곽호영 중앙대학교 기술과학연구소 1989 기술과학연구소 논문집 Vol.19 No.-

As a result of continuing efforts to improve the circuit performance, the number of devices in the package such as VLSI and the speed of computation has been considerably increased. In fact, during the past two decades the heat flux at the chip level has increased by more than an order of magnitude. Therefore one of the problems faced by engineers who are designing computers, is how to cool the electronic hardware of the computer. The LSI or VLSI chips must be cooled in a manner that the maximum temperature of device junction dose not exceed 85℃ in order in order to keep the reliability. The method of "air cooling" is enough to cool the components such as tube or transistor because of their relatively low heat generation rate. But it is not enough to cool VLSI with such method. Recently "immersion cooling" is studied to solve that problem by many investigators because heat transfer is more effective than others. This paper describes an experimental study on boiling heat transfer between vertical isoflux plates with asymmetric heating with a dielectric fluid, FC-72. This study found that the channel width is not a significant parameter for immersion cooling with FC-72 and that the heat transfer from the vertical plates is more effective than the horizontal plates. And this study demonstrated the possibility of use of "immersion cooling" between narrow PCB's.

한ㆍ미ㆍ일 물류기업의 M&A 장기성과에 관한 실증적 연구 : 재무적 성과 분석을 중심으로

전호진,박영태 韓國東北亞經濟學會 2008 동북아경제연구 Vol.20 No.2

In this paper, we investigated M&A long-term performance especially focusing on the financial performance. In this paper, we used the event study method which measures a firms value, profitability, stability and growth which calculated by financial ratio analysis. The event study window is 1, 2, 3years before the event date(O day) and 1, 2, 3years after the date. The empirical study used the t-test for 4, 56, 36 samples which was derived from KOREA, U.S., JAPAN, was made with the use of firms value, profitability, stability and growth which calculated by financial ratio analysis. We found that after M&A, tobin'Q, market value was higher than before and after M&A, profitability, growth was higher than before M&A, but current ratio and quick ratio was lower than before except debt ratio. Judging from this, we can conjecture that in case of M&A, there was a positive effect on the firm value, profitability and growth. Therefore, we infer that economics of scale, economics of scope and synergy effect coexisted in M&A between logistics firms. Actually, we conjecture that acquirer firms, using a M&A, find theirs way into new world market, network and gain first mover advantage.

동북아 다자주의의 모색 : KEDO와 TCOG을 넘어서 Beyond KRDO and TCOG

전진호 현대일본학회 2003 日本硏究論叢 Vol.17 No.-

냉전기로부터 다양한 형태의 다자간 협조체제가 동아시아에서도 모색되어 왔다. 그러나 동아시아는 유럽과는 달리 다자간 안보협력체제의 구축에 많은 장애요인이 존재하는 지역이며, 따라서 동아시아의 안보협력 또는 대화채널은 제도화 및 실효성의 측면에서 다른 지역의 다자간 협력체제에 비해 미약한 실정이다. 그러나 1994년의 북미 제네바 합의 이후 동북아에서는 KEDO와 TCOG이라고 하는 새로운 형태의 다자간 협의체가 탄생하였고, 이들은 비교적 성공적으로 운용되어온 동북아의 다자간 협의체로 평가되어 졌다. 그러나 KEDO와 TCOG은 한미일의 3국간 정책협의체로서 구상되고 운용되었기 때문에 동북아 전역을 포괄하는 협의체의 성격을 띠고 있지는 않다. 따라서 KEDO와 TCOG의 범위와 기능을 한미일에 국한시키지 않고 중국과 러시아, 그리고 북한을 대화을 틀 속으로 유도하는 보다 포괄적이고 효율적인 다자간 협의체의 제도화에 관심이 모아지고 있다. 이러한 관점에서 본고는 동북아 6국에 의한 다자간 안보협의체의 제도화를 KEDO와 TCOG의 경험 위에서 검토하고, 동북아의 다자간 협의체의 새로운 유형을 제시하는 것을 목적으로 하고 있다. From the cold war era. there have been lots of attempts to build up multilateral security cooperation regimes. and a few security dialogues(forums) were made in Asia. especially in the Northeast Asia. But it is said that such security dialogues are not working effectively. Because there were too many obstacles for the Asian states to join into the multilateral security regime in Northeast Asia. After the 'framework agreement' between the US and North Korea. the KEDO(Korean Peninsular Energy Development Organization) and TCOG(Trilateral Coordination and Oversight Group) were organized and both of them were estimated as the successful decision-making organization. But KEDO and TCOG was organized as the trilateral(Korea. Japan. US) organization. thus these do not cover the entire Asian states. So it will be possible to enlarge their ranges of participants of KEDO and TCOG. and it will make these organizations more effective and more concrete as the multilateral security cooperation regimes.

강판의 내식성 향상을 위한 환경 친화형 표면처리 : 다중코팅에 의한 시너지 효과 Synergy Effect by Multicoating

전상익,박찬영,류진호,이원기 한국환경과학회 2005 한국환경과학회지 Vol.14 No.1

Because of the toxicity of hexavelant chromium ion, treatments of metallic surface with chromate compounds to retard corrosion are undesirable for safety control in industrial uses and protection of environment. In this study, we investigated several compounds such as inorganic. organic. and polymer materials in order to substitute the chromate conversion treatment on steel sheet. The corrosion property was investigated in a salt spray tester with 3.5 wt.% NaCl at 35℃. The results showed that the zirconium/silane/polymer triple coatings on the galvanized steel exhibited a significant retardation of corrosion. Although the multicoating system needs a cornplexed processing. we can confirm a possibility of development of a chromate-free chemical conversion treatment for galvanized steel sheet.

CIM 데이터베이스 구축을 위한 통합데이터 모델 연구

전진호 명지대학교 증권보험대학원 1999 논문집 Vol.- No.3

반도체레이저의 워셔형 드라이버에 관한 연구

전진우,김호성 중앙대학교 생산공학연구소 1998 생산공학연구소 논문집 Vol.7 No.1

자유공간 광통신의 광원으로 사용되는 반도체레이저의 구동을 위한 고성능 전원에 사용될 워셔(washer)형 커패시터를 고안하고 그 동작특성을 실험하였다. 워셔형 커패시터는 안쪽 반지름이 50mm, 바깥쪽 반지름이 250mm이며 초고주파회로에 사용되는 두께 30mm의 copper cladded 기판을 사용하였다. 반도체 레이져와 에너지 저장 커패시터의 임피던스정합을 고려하여 워셔형 커패시터를 설계하여 실험한 결과 rise time 과 fall time이 10ns이하이며 펄스폭이 20ns 이하인 펄스를 만들 수 있었으며 고효율과 고주파 통신이 가능함을 입증하였다. A washer-type capacitor as an energy storage capacitor used in a driver for the semiconductor laser which is a source of a free space optical communication is devised and its operation characteristics is test. The washer-type capacitor is made of 1 mm thick copper cladded substrate and its inner and outer radius is 50 mm and 250 mm, respectively. Its dimension is decided considering the impedance matching between the impedances laser diode and the washer-type capacitor. The experiments show that rising time and falling time is 10 ns and pulse width is 20 ns. It is believed that the driver with this kind of washer-type capacitor can drive the laser diode higher than several tens of MHz with high efficiency.

한국산 감잎의 Polyphenol 화합물의 생리활성물질의 화학구조 및 효소저해효과

안봉전,최희진,손준호,우희섭,한호석,박정혜,손규목,최청 한국식생활문화학회 2003 韓國食生活文化學會誌 Vol.18 No.5

The lyophilization of the solution extracted from 60 percent of acetone applied to persimmon leaves, the compounding process in accordance with the solution's concentration, and the gel filteration through Sephadex G-50 of biologically activated substances obstructing enzyme activity, such as tyrosinase, xanthine oxidase, and angiotesin converting enzyme (ACE) led to the assumption that polyphenol was the compound serving as biologically activated substances obstructing enzyme activity. Xanthine oxidase involved in pruine metabolism oxidizes hypoxanthine to xanthine and xanthine to uric acid. In the continuous study for natural compound, nine flavan-3-ois have been isolated from the persimmon leaves. The structures of (+)-catechin, (+)-gallocatechin, procyanidin B-1, pyrocyanidin C-1, prodelphinidin B-3, gallocatechin-(4α→8)-catechin, procyanidin B-7-3-O-gallate, procyanidin C-1-3'-3''-3'''-O-trigallate and (-)-epigallocatechin-(4β→8)-epigallocatechin-(4β→8)-catechin were established by NMR and their inhibitory effect on xanthine oxidase activity was investigated. Procyanidin C-1-3'-3''-3'''-O-trigallate showed 94%, 90.69%, 80.90% inhibition at 100(μ)M and inhibited on the angiotension converting enzyme respectively. Procyanidin B-7-3-O-gallate and procyanidin 1-3'-3''-3'''-O-trigallate showed 66%, 63% inhibition at 100(μ)M and inhibited on the xanthine oxidase competitively. Procyanidin C-1-3'-3''-3'''-O-trigallate showed 70% inhibition at 100(μ)M inhibited on the thyrosinase competitively.