• Journal of the Korean Magnetics Society
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• v.26 no.6
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• pp.190-195
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• 2016

We report the effect of pressure varying from 0 to 1500 bar on the magnetic properties of magnetite nanoparticles synthesized from $Fe(OH)_2$ suspension using a high pressure homogenizer without any dispersing agent and oxidant. The observed X-ray diffraction (XRD) patterns showed that all the synthesized nanoparticles had the inverse spinel structure of magnetite. It was found from transmission electron microscopy (TEM) and XRD analysis that the average size of the synthesized magnetite particles could be controlled by the pressure of the high pressure homogenizer. The average particle size was found to range from 21 to 26 nm and decrease with increasing pressure. Magnetic hysteresis measurements performed at room temperature using a vibrating sample magnetometer (VSM) revealed the appearance of a superparamagnetic behavior in the magnetite nanoparticles synthesized at a pressure of 1500 bar.

• Journal of the Korean Magnetics Society
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• v.5 no.1
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• pp.48-53
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• 1995

The structure, magnetic properties and magnetoresistance phenorrena of Ag-Co nano-granular alloy films prepared by a thermal co-evaporation were studied. Supersaturated fee Ag-Co solid solution and fee Co clusters coexisted in the as-deposited state. As Co content increases from 20 to 55 at.% Co, the grain size of the Ag matrix decreases from 147 to $67{\AA}$, and the Co solubility in the Ag matrix increases from 2.5 to 6.7%. Ag-Co alloy films having composition below 25 at.% Co showed mainly superparamagnetic behavior and above that composition, they showed both paramagnetic and ferromagnetic l::ehavior in the as-deposited state. The maximum magnetoresistance of 19% at R. T. and 10 kOe was obtained in the as-deposited 30 at.% Co alloy film. Heat treatment did not improve the MR ratio tecause most of the Co was already precipitated in the as-deposited state.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.192-197
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• 1998

The Mossbauer spectra of the $Ni_{1-x}Cd_xFeAlO_4$ system were investigated with the Cd content x at room temperature. The spectra of the samples exhibit various patterns as follows 1) superparmagnetic relaxation for 0$\leq$x$\leq$0.2, 2) ferrimagnetic sextet for 0.3$\leq$x$\leq$0.5, 3) ferromagnetic relaxation for x=0.6, 0.7, 4) paramagnetic doublet for 0.8$\leq$x$\leq$1, with the Cd content x. In the samples with x values from 0 to 0.2, the substituted $Cd^{2+}$ ions transfer the $Al^{3+}$ ions from A-site to B-site mainly. The superparamagnetic relaxation effect and the ferromagnetic relaxation effect are derived from the $Al^{3+}$, $Cd^{2+}$ respectively. The magnetic structure of the $Ni_{1-x}Cd_xFeAlO_4$ system was explained by the Yafet-Kittel model.

• Investigative Magnetic Resonance Imaging
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• v.14 no.1
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• pp.31-40
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• 2010

Purpose : To compare the relative values of various fast breath-hold imaging sequences for superparamagnetic iron-oxide (SPIO)-enhanced hepatic MRI for the assessment of solid focal lesions with a 3T MRI unit. Materials and Methods : 102 consecutive patients with one or more solid malignant hepatic lesions were evaluated by spoiled gradient echo (GRE) sequences with three different echo times (2.4 msec [GRE_2.4], 5.8 msec [GRE_5.8], and 10 msec [GRE_10]) for $T2^*$-weighted imaging in addition to T2-weighted turbo spin echo (TSE) sequence following intravenous SPIO injection. Image qualities of the hepatic contour, vascular landmarks and artifacts were rated by two independent readers using a four-point scale. For quantitative analysis, contrast-to-noise ratio (CNR) was measured in 170 solid focal lesions larger than 1 cm (107 hepatocellular carcinomas, nine cholangiocarcinomas and 54 metastases). Results : GRE_5.8 showed the highest mean points for hepatic contour, vascular anatomy and imaging artifact presence among all of the subjected sequences (p<0.001) and was comparable (p=0.414) with GRE_10 with regard to lesion conspicuity. The mean CNRs were significantly higher (p<0.001) in the following order: GRE_10 ($24.4{\pm}14.5$), GRE_5.8 ($14.8{\pm}9.4$), TSE ($9.7{\pm}6.3$), and GRE_2.4 ($7.9{\pm}6.4$). The mean CNRs of CCCs and metastases were higher than those of HCCs for all imaging sequences (p<0.05). Conclusion : Regarding overall performances, GRE using a moderate echo time of 5.8 msec can provide the most reliable data among the various fast breath-hold SPIO-enhanced hepatic MRI sequences at 3T unit despite the lower CNR of GRE_5.8 compared to that of GRE_10.

• Journal of Korean Medical classics
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• v.19 no.3
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• pp.260-273
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• 2006

본과제종림상실천각도탐토료장우화자혈법대후세의학적영향(本課題從臨床實踐角度探討了張于和刺血法對後世醫學的影響). 문중나열종원(文中羅列從元), 명(明), 청지현대적19위의가용자혈법치료질병적경험, 무론종병종(無論從病種), 병위(病位), 용혈화침자공구방면(用穴和針刺工具方面), 재장자화기초상도유료흔대발전. 특별시재외과화후과방면(特別是在外科和喉科方面), 경시풍부다채, 현시료차료법적생명력(顯示了此療法的生命力). 통과본과제적연구득출여하결론(通過本科題的硏究得出如下結論). 장자화재외과천장취환부방혈(張子和在外科擅長取患部放血), 경원(經元), 명(明), 청(淸), 연용도금천(沿用到今天), 시장씨영향력적최대증명(是張氏影響力的最大證明). 기차(其次), 장자화지후적명대(張子和之後的明代), 외과운용자혈법적병종대증(外科運用刺血法的病種大增), 포괄정창, 시독(時毒), 발배(發背), 뇌저(腦疽), 투침지, 오양, 연진창(緣唇瘡), 역양등, 발전료장씨지학(發展了張氏之學). 우기재후과(尤其在喉科), 출현계승여발전적명현궤적(出現繼承與發展的明顯軌跡), 장자화용소상(張子和用少商), 환부치후비(患部治喉痺), 지명대증가십의(至明代增加十宜), 삼상(三商), 청대증가곡지, 위중(委中), 양교(陽交), 간사(間使), 대릉(大陵), 도현대칙재증가이혈(到現代則再增加耳穴), 대추(大椎), 천계등(天桂等).

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.455-455
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• 2017

최근 기후변화로 인한 도시홍수 피해가 증가하고 있다. 이에 따라 본 연구에서는 기상청에서 제공하는 HadGEM3-RA의 한반도(12.5km) 기후변화 RCP 4.5 및 RCP 8.5시나리오에 대해 편의보정 및 시간상세화를 실시하여 기후변화를 고려한 수문분석을 하였다. 기후변화 시나리오의 편의보정은 Gamma분포를 이용한 모수적 분위사상법과 관측자료의 누가확률분포를 이용하는 비모수적 분위사상법으로 수행하였으며, 관측된 분 단위 강우자료를 기반으로 기후변화 시나리오 미래기간에 대해 시간상세화를 실시하였다. 또한, 도림천유역을 중심으로 기후변화 시나리오 미래기간의 확률강우량과 설계홍수량을 산정하였다. 본 연구에 결과는 수문분석을 위한 기후변화 시나리오 시간상세화 방안에 크게 기여 할 것으로 판단된다.

• Archives of design research
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• v.15 no.4
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• pp.275-284
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• 2002

To improve the social and economic position of the disabled people and secure their human rights, an integrated society should be buill. To build such a society, an adequate access should be provided to the movement or in using buildings or facilities. The inconveniences from social life on the part of the disabled people might not result from their impairment or disability, but from physical and social barriers in the environment surrounding them. Therefore, it is necessary to reconstruct entire systems of the society as a disabled people-friendly structure in order to remove those barriers, make them stand their own feet in our communities and freely participate in the social activities. This will eventually lead to build a society in which all people including the disabled people can use those facilities in a more convenient way. It is almost impossible for the disabled people to safely and conveniently access to and use facilities and equipments and freely move to their desired places, without any help from others in Korea. Even though, there are currently many disabled people-related convenience facilities, they have been independently built without a connection with other facilities and buildings, thus not greatly useful. Even when convenience facilities have been built, mostly they are superficially set up; therefore, in many cases, the disabled peOple cannot use those facilities. In this. research, I tried a new concept of mobile wheelchair lift design, which the disabled people can operate without restrictions, when using the public facilities. The key to this research was to develop the existing import-oriented simple functional products to a new system with functional safety and high quality orientation. Also, this research aimed at bringing an. import substitution effect, as well as preempting the mobile wheelchair lift market by advancing into overseas markets through application of new image designs in the field of disabled people aid equipments.

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.325-338
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• 2003

Video adaptation in response to dynamic resource conditions and user preferences is required as a key technology to enable universal multimedia access (UMA) through heterogeneous networks by a multitude of devices In a seamless way. Although many adaptation techniques exist, selections of appropriate adaptations among multiple choices that would satisfy given constraints are often ad hoc. To provide a systematic solution, we present a general conceptual framework to model video entity, adaptation, resource, utility, and relations among them. It allows for formulation of various adaptation problems as resource-constrained utility maximization. We apply the framework to a practical case of dynamic bit rate adaptation of MPEG-4 video streams by employing combination of frame dropping and DCT coefficient dropping. Furthermore, we present a descriptor, which has been accepted as a part of MPEG-21 Digital Item Adaptation (DIA), for supporting terminal and network quality of service (QoS) in an interoperable manner. Experiments are presented to demonstrate the feasibility of the presented framework using the descriptor.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.36-36
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• 2003

목적： 고형성 종양에 특이적으로 발현하는 MR 분자영상용 조영제의 후보물질을 분자생물학적 방법 및 in vitro 분자영상기법을 이용하여 탐색하고자 하였다. 대상 및 방법： 암이 진행됨에 따라 유전자가 과발현되는 세포표면 단백질인 CD44 와 세포막에 존재하는 단백질분해효소의 일종인 MTI-MMP를 일차 선정하여 유전자 수준 및 단백질 수준에서 분자생물학적 방법으로 종양특이성에 대해 검증하였고, 특히 각종 암세포에서 발현양이 증가하는 CD44의 변형인 CD44v6 항체를 이용하여 생세포에서의 표적화에 대한 광학적 검증을 위해 초상자성 나노입자 대신 형광입자(FITC)를 결합하여 confocal microscopy로 실시간 표적화에 대한 분자영상을 획득하였다.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.277-283
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• 1993

The temperature dependence of DC magnetic susceptibilities of three austenitic Fe-Cr-Ni stainless alloys were measured in the temperature range of 4.2 and 300 K. Two alloys support a general magnetic description of austen-itic stsinless steels in terms of a two-magnetic-phase (spin glass + superparamagnetic cluster) model and one alloy shows magnetic double transition phenomena. Also this study shows that incressing the Ni/Cr ratio in Fe-Cr-Ni alloys causes a increase of the DC susceptibility peak value and a decrease of the magnetic transition temperature.