공침법에 의한 BiDy₂Fe_(5)O_(12) 결정형 나노입자 분말의 제조 및 응용 연구

홍영대,조정환,김태엽,전성욱,홍영명 고신대학교 자연과학연구소 2007 고신대학교 자연과학연구소 논문집 Vol.14 No.-

금속산화물들은 각종 산업재료로서 유용하며 더욱이 그것들의 결정형 나노입자를 경제적으로 제조하는 기술은 21세기 첨단산업에 매우 중요하다. 저자들은 前報에서 화학합성법에 의한 각종 금속산화물의 나노입자를 제조하는 표준공정법을 연구하여 보고하였다. 본 연구에서는 그 표준공정법을 이용하여, 가넷의 일종인 BiDy_(2)Fe_(5)O_(12) 결정 나노입자 분말을 제조하고 그것의 자성체로의 응용을 위해 제품특성을 조사하었다. 가네트 제조과정에 필요한 침전물은 제품설계에 의거 몰비로 계산된 Bi, Dy, Fe의 질산염들의 혼합수용액에 침전제로서 pH NH_(3)-NH_(4)CI 완충용액 일정량을 가하여 얻어졌다. 이렇게 제조된 침전은 열처리과정을 거처 BiDy_(2)Fe_(5)O_(12) 결정형 나노입자 분말로 만들어졌다. 얻어진 제품의 입자크기, 조성, 결정구조 및 광자기성 등 특성시험이 SEM, ICP, XRD, 그리고 VSM 등을 사용하여 실시되었다. 각종 분석법을 사용하여 제품의 특성을 조사한 결과, 최초에 설계한 대로의 자성체가 나노 크기의 분말로 얻어졌으며 이것을 통하여 전보에서 확립한 표준공정법의 유효성도 입증되었다. Metallic oxides are useful as various industrial materials. Futhermore, the cost-effective techniques of fabricating the crystalline nanopartides of metallic oxides are very important for the high-tech industries of the 21 century, In the previous study, the authors reported the standard process for the preparation of crystalline nanoparticles of metallic oxides by chemical synthesis, In this study, BiDyzFesOiz nanoparticles were prepared by using the reported standard process and the characteristics of the product were investigated for applicability as magnetic substance. The precipitation needed for manufacturing process of garnet was made by adding the NH_(3)-NH_(4)CI buffer solution of pH 10 to the mixed solution of bismuth (III) nitrate, dysprosium(III) nitrate and iron(III) nitrate. The amount of each nitrate was calculated by the designed mole ratios. The nano-size crystalline powders of BiDy_(2)Fe_(5)O_(12) were earned by heating the precipitation at 800℃ for 4 hours in air. The characterizations, such as particle size, composition, crystal structure and magneto-optical property of garnet were tested by SEM, ICP, XRD, and VSM analyses. The results of the analyses showed the following two facts. First, a good magnetic substance of BiDy_(2)Fe_(5)O_(12) was earned as crystalline nano-size powders according to the original design. Next, the established standard process for the fabrication of METALLIC oxides nanonartieles was approved as a very effective method.

高周波 通信用 FIR Digital 필터의 設計

洪國泰,李成大,鄭康敏 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

In this paper, a programmable high-sample-rate FIR digital filter was designed for a highbandwidth communication system. A fully parallel bit-level pipelined transpose-form carrysave architecture using CSD coefficients was adopted for high-speed operation. In this system, multiplication can be translated to simple shift-addition processes. For programmability of filter coefficients, two decoders and a few registers are added, and the shifting processes of input data are controlled according to the data registered. Therefore, the speed performance of the designed filter is comparable to the case of a non- programmable filter.

간질발작후 MRI 영상에서 뇌 종창을 보인 3예 보고

홍현숙,김대호,이혜경,박재성,박성진,조준희,차장규,백상현 순천향의학연구소 2004 Journal of Soonchunhyang Medical Science Vol.10 No.2

We report seizure induced brain swelling in three patients. MRI revealed a cortical, subcortical(3/3), and basal ganglia(2/3) high signal intensity on T2- weighted and FLAIR images. The lesion shows low signal on T1-weighted image, and enhanced after contrast administration. Follow up study after 27 days in one case revealed complete resolution of the lesion. The reversible MRI findings may be the results of a local brain swelling, breakdown of blood-brain permeability, and a defect of cerebral autoregulation during seizure activity. The transient nature of such findings have to be considered in the differential diagnosis such as reversible ischemia, migraine, inflammation and infection.

표본화 및 유지회로 성능향상에 관한 연구

홍국태,이성대,정강민 成均館大學校 科學技術硏究所 1995 論文集 Vol.46 No.1

In this paper, a high speed, high accuracy sample and hold circuit that minimizes the hold step error by using a new circuit architecture is proposed. This new sample-and-hold scheme takes advantages of the speed of the open loop sample-and-hold circuit in the SAMPLE time and the cancellation of charge injection in the HOLD time. It operates above 50MHz with 0.3mV hold step error.

교맥 에탄올 추출물의 멜라닌생성 억제효과

김대성,노성택,이장천,임규상,신미란,우원홍,문연자 한국전통의학연구소 2006 한국전통의학지 Vol.15 No.1

The aim of this study was to investigate the effect of ethanol extract of Fagopyrum escuentum(FE) on the melanogenesis. To determine whether ethanol extract of FE suppress melanin synthesis in cellular level, B16F10 melanoma cells were cultured in the presence of different concentrations of FE ethanol extract. In the present study, the author examined the effects of FE ethanol extract on cell proliferation, melanin contents, tyrosinase activity. Cell proliferation was slightly increased by treatment with ethanol extract of FE (25-200 ㎍/ml). The ethanol extract of FE effectively suppressed melanin contents at a dose of 100 ㎍/ml. It was observed that the color of cell pellets was totally whitened compared with the control. The ethanol extract of FE inhibited tyrosinase activity, regulate melanin biosynthesis as the key enzyme in melanogenesis. These results suggest that the ethanol extract of FE exerts its depigmenting effects through the suppression of tyrosinase activity. And it may be a potent depigmetation agent in hyperpigmentation condition.

주폐자충 폐렴으로 발현된 Felty 증후군 1예

김성호,남대근,문재현,김지홍,김보석,안진광,문태건,안병재,김성일 全南大醫大 2001 전남의대학술지 Vol.37 No.3

원발성 두개골내 수막종 : 1예 보고 A Case Report

김대호,홍현숙,조준희,박재성,박성진,차장규,백상현,이혜경 순천향의학연구소 2004 Journal of Soonchunhyang Medical Science Vol.10 No.2

Primary intraosseous meningioma of skull is rare, and often confused with a primary bone tumor. We report a case of a 71 years old female patient with an intraosseous calvarial meningioma of frontal bone presenting as a solitary osteolytic skull lesion. Plain skull radiograph, CT and MR images show sharply marginated expansile bony lesion in frontal skull vault, and a small well enhanced soft tissue mass within bone. The mass is extracranially protruded to scalp, and is partially attached to the underlying dura. Outer and inner table of skull vault is slightly bulged out, suggesting intradiploic origin of the tumor. The tumor was treated with surgical excision and cranioplasty. Histological examination revealed fibrous meningioma.

해수교환방파제의 항내 해수순환 효과에 관한 실험적 연구

김성득,이성대,민석진,홍창배 한라대학교 2007 論文集 Vol.10 No.-

Establishing breakwater in ports have greatly improved the calmness in ports. However, the seawater exchange between landward and seaward areas in ports has greatly decreased. In ports near urban areas, the inflow of sewage or industrial wastewater and the accumulation of sludge are causing a variety of environmental problem. To realize a seawater exchange breakwater that will improve the calmness in ports and the seawater exchange, the tunneled caisson breakwater with intake holes was debeloped to allow fresh seawater into the port using wave energy. The seawater exchange breakwater composed of tunneled breakwater and submerged mound is under planned in Hupo fishing port on the East Sea. In this paper, the characteristics of seawater exchange and the inflow rate of this breakwater introduced based on the results of 3-dimensional hydraulic model tests.

MVC알고리즘 이용한 효율적인 MPEG 동영상분할

전대홍,김영호,강대성 동아대학교 정보기술연구소 2002 情報技術硏究所論文誌 Vol.9 No.2

This paper proposes the mean value comparison algorithm(Mean Value Comparative Algorithm) for MPEG video segmentation. Shot detection that segments MPEG video sequence is important work and first step for video index and retrieval as being most basic. Usually, segmentation algorithm used much has a defect that occurs a error detection according to screen change of camera lights' flash etc. or fast movement of body or movement of camera, because of comparing former frame with present frame. Therefore I appropriated Shot point that detects at traditional algorithm and distinguished once more through comparing its mean value with abutting frames in this paper. I could detect more corrective shot than traditional algorithm by experiment result.

폐타이어 방파제의 파랑제어 효과에 관한 실험적 연구

이성대,남미영,홍창배 한라대학교 2007 論文集 Vol.10 No.-

One of the central problem in the study of the coastal surface wave environment is predicting the transformation of waves as they propagate towards the shore. The transformation is mainly due to existence of obstacles such as breakwaters and vertical cylinders. In general, the types of wave transformation can be classified as follows; wave diffraction, reflection, transmission, scattering, radiation et al. This research deals with the wave transmission and dissipation problems for two dimensional regular waves and scrap-tire vertical breakwater. Using the unsteady mild slope equation, a numerical model has been developed to calculate the reflection and transmission of regular waves from a multiple-row scrap-tire breakwater and vertical cylinders. In addition hydraulic model experiments have been conducted with different values of properties between the piles and opening ratio (distances) between the rows of the breakwater. It is found that the transmission coefficients decrease with decreasing the opening ratio and increasing the rows of vertical cylinders. Comparison between hydralic and numerical experiments results shows resonable agreement.