Lifting을 이용한 고저항 고장 검출에 관한 연구

고윤석,홍대승 남서울대학교 2004 남서울대학교 논문집 Vol.10 No.2

The research presented in this paper focuses on a method for the detection of High Impedance Fault(HIF). The method will use the Lifting and neural network system. HIF on the multi-grounded three-phase four-wires primary distribution power system cannot be detected effectively by existing over current sensing devices. These paper describes the application of lifting scheme to the various HIF data. These data were measured in actual 22.9kV distribution system. Wavelet transform analysis gives the frequency and time-scale information. The neural network system as a fault detector was trained to discriminate HIF from the normal status by a gradient descent method. The proposed method performed very well by proving the right state when it was applied staged fault data and normal load mimics HIF, such as arc-welder.

항결핵 치료과정에서 호전되었다가 악화된 뇌 결핵종 1예 보고

이대훈,유진홍,강미자,김홍기,김선화,고동훈,천지성,유원종 대한화학요법학회 1997 대한화학요법학회지 Vol.15 No.3

In spite of nationmide tuberculosis control program, tuberculosis is still prevalent in Korea. Accordingly, tuberculous meningitis also poses one of the main trouble some problems. Recently, We experienced a perplexing case of tuberculous menin-gitis and tubercdoma in a 24-year old female patient. She was admitted to our hospital owing to meningeal irritation sign, aphasia, VI nerve palsy, and ,fever. CSF analysis showed a finding consistent with that of presumptive tuberculous meningitis.. Initial MRI of the brain revealed a large mass(tuhercu1oma) on left parieto-temporal area. Antitubeculous regimen(1soniazid (INH), rifampin(RMP), ethambutol(EMB), pyrazinamide(PZA)} of meningeal dose was given immediately, and her symptoms and signs were dramatically disappeared with a few days after treatment. She was discharged with improved condition and under maintenance treatment of tuberculosis. Follow-up one year after treatment. revealed that the previous lesion was nearly diminished. She showed no symptom at all until she recognized a total blindness of sudden onset on her left eye a t the 18th month of treatment. Brain MRI checked at that time showed multiple masses of tuberculoma scattered over the brain base and one of them invaded left optic nerve. In our opinion, the cause of relapse in this patient might he explained by the selection and ultimate replication of a minor population of resistant strain. Although such relapse is an extremely rare event, we think that we should always pay attention to this possible resistance problem every time we meet patients with tuberculous meningitis.

저저항 SALICIDE Gate 공정 개발 연구

김은하,최효직,고대홍 연세대학교 산업기술연구소 1999 논문집 Vol.31 No.2

Formations of TiSi₂ thin films by a solid state reaction between Ti thin films and Si substrates and the effects of the conditions of Si substrates have been investigated. Low-Resistant C54- TiSi films were formed by rapid thermal processes at 750℃ on the undroped Si (100) substrate, and at 800℃ on the As or B-doped Si (100) substrate as well as on As or B-droped poly-Si substrates. Cross-sectional TEM analyses confirmed the formation of small-grained C49 TiSi₂films by rapid thermal processes at 700℃ on pre-amorphized poly-Si substrate by As implantation. The temperatures of the transformation to the C5 phase decreased in small-grained C49- TiSi₂films. Finally, low resistant C54 TiSi₂thin films were selectively formed on gate, source, and drain regions by SALICIDE process with pre-amorphizaton of substrates. Microstructures and electrical properties of TiSi₂ film were investigated. Sheet resistance of TiSi₂ film on 1.2㎛-wide poly-Si gates was 3.8~4.2Ω/□, and XRD results showed phase formation of C54 TiSi₂ films.

Al6061 판재성형에서 핫 포밍 퀜칭의 성형성 및 기계적 특성 평가

고대훈(Dae Hoon Ko),김재홍(Jae Hong Kim),이찬주(Chan Joo Lee),고대철(Dae Cheol Ko),김병민(Byung Min Kim) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.4

알루미늄 소재의 냉간 판재성형에서는 낮은 성형성과 성형 후 과도한 스프링백에 의한 치수정밀도가 저감되는 문제가 있다. 이에 본 연구에서는 기존 제조공법의 문제점을 개선하기 위해 새로운 제조공법인 Hot forming quenching(HFQ)을 제시하고자 한다. HFQ 은 용체화처리 온도로 가열된 알루미늄 판재를 열간성형하고, 다이 내에 설치된 냉각채널에 의해 퀜칭하여 열간성형과 열처리를 동시에 함으로써 성형성 향상, 스프링백 저감 효과를 얻을 수 있다. 기존의 냉간성형 대비 HFQ 의 성형성 향상효과를 에릭슨 시험을 통해 평가하였다. 스프링백 특성을 파악하기 위해 V-beding 시험에 HFQ 를 적용하여 굽힘 성형된 제품의 치수정밀도를 기존의 냉간성형과 비교하였다. 또한 강도 및 경도를 측정하여 기존 냉간 성형에 의한 값들과 비교함으로써 알루미늄 제품 성형에 HFQ 을 적용하기 위한 타당성을 평가하였다. In aluminum sheet metal forming, the conventional forming methods of T4 or T6 heat-treated sheets result in low formability and dimensional accuracy. This study suggests a new forming method for aluminum sheets called as hot forming quenching (HFQ) that solves the problems faced in the conventional method. HFQ combines the heat treatment and forming processes through the forming die during the quenching of a solid solution. To evaluate the application of HFQ to the sheet forming of aluminum, an Erichsen and V-bending test are performed in this study to measure the dimensional accuracy and formability, which are then compared with those of the conventional forming method. Furthermore, the strength and hardness of the products formed by HFQ are measured to confirm the degradation in mechanical properties compared with the conventional forming method, which shows the validity of the application of HFQ to aluminum sheet metal forming.

고랭지 억제재배에 적합한 수출용 오리엔탈나리 신품종 선발

홍대기(Dae-Ki Hong),고재영(Jae-Young Ko),최강준(Gang-Jun Choi),노희선(Hee-Sun Noh),홍계완(Kye-Wan Hong) 한국원예학회 2011 한국원예학회 학술발표요지 Vol.2011 No.5

가속열화수명실험을 위한 EB-A 파괴단말 설계 및 평가

김대훈(Dae-Hoon Kim),손용대(Young-Dae Son),홍동석(Dong-Suk Hong),고현상(Hyeon-Sang Ko),엄주홍(Ju-Hong Eom) 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.10

Understanding the Epitaxial Growth of Se_<i>x</i>Te_<i>y</i>@Te Core−Shell Nanorods and the Generation of Periodic Defects

Moon, Geon Dae,Min, Yuho,Ko, Sungwook,Kim, Sun-Wook,Ko, Dae-Hong,Jeong, Unyong American Chemical Society 2010 ACS NANO Vol.4 No.12

<P>This study demonstrates solution-processed epitaxial growth of Te on Se<SUB><I>x</I></SUB>Te<SUB><I>y</I></SUB> nanorods and the generation of periodic defects in the core. We investigated Se<SUB><I>x</I></SUB>Te<SUB><I>y</I></SUB>@Te core−shell nanorods with a diameter of 40−50 nm and a length of 600−700 nm. In spite of a large lattice mismatch between the Se<SUB><I>x</I></SUB>Te<SUB><I>y</I></SUB> core and the Te shell, the soft character of the core and the shell at a high reaction temperature allowed epitaxial growth of Te on the Se<SUB><I>x</I></SUB>Te<SUB><I>y</I></SUB> nanorods. During the cooling process to room temperature (below the glass transition temperatures), the lattice mismatch between the core and the shell led to homogeneous stress along the epitaxial interface so that periodic defects were generated in the core.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-12/nn102196r/production/images/medium/nn-2010-02196r_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn102196r'>ACS Electronic Supporting Info</A></P>

Selective Epitaxial Growth of GaAs on a Si (001) Surface Formed by an In Situ Bake in a Metal-Organic Chemical Vapor Deposition Reactor

Cho, Young-Dae,Lee, In-Geun,Jung, Mi-Jin,Shin, Hyunsu,Jun, Dong-Hwan,Shin, Chan-Soo,Park, Kyung-Ho,Park, Won-Kyu,Kim, Dae-Hyun,Ko, Dae-Hong American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.5

<P>We here report selective epitaxial growth of GaAs layers on Si (001) substrate with V-grooved trench using the aspect ratio trapping method. The V-grooved Si surface on the bottom of Si trenches was formed through a high temperature in situ baking process in H-2 atmosphere before growth of GaAs in a metal-organic chemical vapor deposition (MOCVD) chamber. The evolution of the V-grooved shape and the density of defects in selectively grown GaAs epitaxial layers are reported as a function of high temperature bake times before GaAs growth by using both high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD).</P>

Ni_(1-x)Cd_(x)FeAlO₄의 Mo¨ssbauer 효과

고정대,홍성락 제주대학교 기초과학연구소 2002 基礎科學硏究 Vol.15 No.1

The crystal structure and magnetic properties of the Ni_(1-χ)Cd_(χ)FeAlO)(4) (0≤χ≤0.5) have been investigated by means of X-ray diffractometry and Mo¨ssbauer spectroscopy. The samples(0≤χ≤0.5) have been prepared by the ceramic sintering method. The X-ray diffraction pattern shows that the crystal structure of the samples is a cubic spinel type. The lattice constant has been found by extrapolation using the Nelson-Riley function and it increases slightly from 8.321 A˚ to 8.410 A˚ with Cd concentration. The Mo¨ssbauer spectra for x<0.4 show a superposition of two sextets and a paramagnetic doublet at room temperature. The cation distribution for x=0 was determined to be [Fe_(0.75)Al_(0.25)]^(A) [NiFe_(0.25)Al_(0.75)]^(B)O₄. The superparamagnetic doublet for x<0.4 seems to be due to Al ion in tetrahedral site by the superparamagnetic clustering effect.

Mossbauer Spectroscopy에 의한 제주 화산암의 구조적 연구(Ⅱ)

洪性樂,高正大 濟州大學校 基礎科學硏究所 1989 基礎科學硏究 Vol.2 No.1

본 연구에서는 제주도 한라산 북쪽 고지대(1100m)로부터 저지대(200m)까지 존재하는 화산암을 채취하여 Mossbauer spectrum을 측정하고 화산암을 구성하는 주된 광물인 olivine내의 Fe이온의 물성을 조사하였다. 고도별로 채취한 제주도 화산암의 Mossbauer spectrum은 주로 olivine에 의한 한쌍의 quadrupole splitting을 나타낸다. 이들 화산암의 isomer shift 값과 quadrupole splitting 값으로부터 화산암에 함유된 Fe는 주로 ?? 상태로 존재함을 알 수 있었다. 또한 고도별로 채취한 제주도 화산암의 Mossbauer spectrum의 공명흡수면적은 고도가 높을수록 증가함을 알 수 있었다. Mossbauer parameters of Cheju volcanic rock with increasing altitude are measured at the room temperature. The values of isomer shift and quadrupole splitting shows sthat samples is composed to be in ?? ionic state. The values of absorption area are increased as altitude is heightened.