Cu 치환에 따른 Ni-Zn 페라이트의 전자파 흡수 특성

오영우,이선학,김종령,안용운,이승관 경남대학교 신소재연구소 2001 신소재연구 Vol.13 No.-

고상반응법을 이용하여 Ni_0.6-xCuZn_0.4Fe _2O_4(x=0, 0.1, 0.2, 0.3) ferrite 분말을 제조하고 1200℃에서 열처리하여 Cu 치환에 따른 입자변화와 전자파흡수 특성과의 관계를 조사하였다. Ni 자리에 Cu를 0.1mol 치환했을 때는 포화자화값은 큰 변화 없이 일정하였고 우수한 전자파습수능을 나타내었고, 그 이상 첨가 시는 포화자화값과 전자파흡수능은 직선적으로 감소하였다. Ni_0.6-xCuZn_0.4Fe _2O_4 ferrite powder was prepared by the solid-reaction method and sintered at 1200℃ and investigated grain size related with electromagnetic wave absorbing properties were investigated as a function of Cu substitution. The saturation magnetization and electromagnetic wave absorbing efficiency were rarely changed until substitution of Cu 0.1mol into Ni-site, but decreased strongly over 0.1mol Cu,

심미수복재의 수복방법과 광조사기기에 따른 치질과의 인장결합강동에 관한 연구

오행진,김영관,황호길 大韓齒科保存學會 1996 Restorative Dentistry & Endodontics Vol.21 No.2

용융염합성법에 의한 Ba-페라이트 미립자의 형상 제어

오영우,이승관,김영근 경남대학교 신소재연구소 1996 論文集 Vol.7 No.-

용융염 합성법으로 Ba-페라이트 미세입자를 합성하기 위하여, 염으로 NaCl과 KCl을 선택하였으며, 이들을 단독 또는 NaCl-KCl의 공정 조성 혼합물로서 시료에 50wt% 첨가하고, 바륨 페라이트의 입자형상을 제어하기 위해 1㏖%의 SiO₂를 첨가 하였다. 보자력 제어를 위한 BaFe_(12-2x)Co_(x)Ti_(x)O_(19) 조성에서 x=0→x=1.0으로 Fe^(3+)를 Co^(3+), Ti^(4+)로 치환량이 증가할수록 H_(c)와 M_(r)값은 큰 폭으로 감소하였고, SiO₂를 1㏖% 첨가한 경우는 첨가하지 않은 경우보다 6각 판상의 c축이 짧아졌고 판상비가 커졌다. In order to synthesize Ba-ferrite fine particles by molten salt method, NaCl and KCl were added to basic composition to 50% by weight, and added 1 mole% of SiO₂to control the shape of the Ba-ferrite particles. H_{c} and M_{r} were decreased when Fe^{3+} was substituted with Co^{2+} and Ti^{4+} from x=0 to x= 1.0 in BaFe_{12-2x}CO_{x}Ti_{x}O_{19}, and 1 mole% SiO₂increased the size but shortened c-axis of hexagonal ferrite.

(Mn Mg)Fe₄+O+δ조성의 저항-온도 특성

오영우,이승관 慶南大學校 附設 工業技術硏究所 1999 硏究論文集 Vol.17 No.-

??의 식에서 x를 0.0∼0.2로 변화시키고, 하소온도를 800 ℃, 소결온도를 1100∼1300℃로 50℃ 간격으로 변화시켜 저항(R)-온도(T)의 특성을 측정하였다. 온도가 증가함에 따라 저항은 지수함수적으로 감소하는 NTC 서미스터의 특성을 나타내었으며, 1200℃에서 소결한 x=0.1 시편에서 가장 양호한 직선성을 나타내었다. 25와 85℃를 기준으로 계산한 Β 상수는 5000에서 7300 [K]의 범위를 나타내었으며, 이는 기존의 Mn-Co-Ni계 서미스터와 같은 범주의 경향을 보였다. 25℃일 때 저항온도계수(α)는 1200℃에서 소결한 x=0.1에서 -5.2 %/℃를 나타내었다. 이로써 본 실험의 조성으로 Mn-Ni-Co 계 서미스터의 대체 재료로서의 가능성을 확인할 수 있었다 ??(x=0.0, 0.025. 0.1. 0.2) for NTC(negative temperature coefficient) thermistor was prepared by calcining at 800℃ and sintering at from 1100 to 1300℃ with 50℃ intervals while x was varied from 0.0 to 0.025, 0.1 and 0.2. The best linear property was obtained in the based specimen sintered at 1200℃ with x=0.1 composition. Thermistor parameter, ??, was in the range of 5000∼7300 [K]. Temperature coefficient of resistance, ??, was -5.2%/℃. The results showed the possibility that Mn-Ni-Co based thermistor could be substituted by the composition used in this study was confirmed.

층위구조와 운율구조를 통한 음절분석

오관영 여수대학교 2001 論文集 Vol.16 No.-

The purpose of this paper is to suggest a new approach to syllable structure, which can show the whole processes of stress shift and vowel alternations. The approaches I have attempted to show in this paper are three types, these being rule-based, prosodic, and harmonic approaches. However from the comparison of existing methods we can find a few problems in dealing with stress shift and vowel laxing compositely. They dealt with the syllable just partially on the linear, which made us overlook the other important phenomena in the syllable structure. When we look at the stress movement, it causes the vowel lax or tense. Therefore the words related with the phenomena will be dealt with consideration to dual sides. Now this paper will adopt the level approach to show more appropriate explanation than the existing analysis.

Photoluminescence과 Conductance 측정을 이용한 자외선 조사된 Ge첨가 다성분계 산화물 유리의 구조변화 관찰

이회관,오영석,강원호 단국대학교 2001 산업기술연구 Vol.2 No.-

Ge-doped multicomponent oxide glasses were prepared by a conventional melting method. The structural change around Ge ions was investigated by using PL(photoluminescence) and conductance(G). After UV irrdiation, the PL intensity decreased and the change were maintained at room temperature, but a photodarkened glass recovered near its original properties when it was heat-treated at 500℃ for several hours. The conductance of the irradiated sample decreased because the disorder in structure was happened by UV irradiation. These results can be explained a structural change were occurred at bonding structure between Ge ions and glass components.

데페록사민 전처치가 토끼 심근경색 크기의 감소에 미치는 효과

양관모,오동렬,박승현,박규남,이원재,김형국,황두영,최승필,채장성 대한응급의학회 1998 대한응급의학회지 Vol.9 No.4

Background: Reperfusion of ischemic myocardium has been postulated to result in a specific oxygen radical mediated tissue injury. Iron may liberate during ischemia and we hypothesized that administration of the iron chelator, deferoxamine during ischemia would result in improved recovery after postischemic reperfusion. Purpose: To test whether iron-catalyzed processes contribute to myocardial necrosis during ischemia and reperfusion, deferoxamine was administered to block iron catalyzed hydroxyl radical formation in rabbits. Methods: Eleven rabbits were divided into two groups : control group (n=5) and deferoxamine pretreatment group (n=6). The left circumflex coronay artery was ligated for 30 minutes and reperfused for 180 minutes. Area at risk (AR) was measured by non-stained area with methylene blue injection into left atrium after left circumflex coronary artery ligation. Infarct size was measured by weighing after triphenyltetrazolium chloride staining. Heart rate was measured using electrocardiographic recording and systemic blood pressure was monitored by pressure transducer connected to the catheter in the left ventricle. Results: 1. There was no significant difference of heart rate and blood pressure in deferoxamine pretreatment group compared with control group. 2. There was significant decrease of serum iron concentration after continuous infusion of deferoxamine compared with serum iron concentration before ligation of coronary artery(P<0.05). 3. There was no significant difference of area at risk between control and deferoxamine pretreatment group. 4. Area at necrosis to area at risk was significantly reduced in deferoxamine pretreatment group compared with control group(P<0.05). The results suggest that deferoxamine infusion prior to coronary artery occlusion has a significant benefit in reducing infarct size in this model.

하악 시상골 절단술 후 고정 방법에 따른 회귀 성향에 대한 비교 연구

배진오,이동근,오승환,신기영,장관식 대한악안면성형재건외과학회 2000 Maxillofacial Plastic Reconstructive Surgery Vol.22 No.2

Objective : To compare two different methods of rigid fixation in postoperative stability after mandibular setback, Material and Methods : 28 patients with Class III malocclusion were treated by bilateral sagittal split ramus osteotomy(BSSRO) and mandibular setback were selected for this study. Group A(n=14) had the bone segments fixed with monocortical miniplate on the lateral side of the mandibular body and Group B(n=14) had three noncompressive bicortical screw inserted at the genial area through a transcutaneous approach. Cephalograms were taken preoperatively, postoperatively within 1 weeks and at a follow-up period (mean 8.9 months after surgery) and the amount of setback and postoperative change were measured. Results : Postoperative relapse between two groups was minimal in setback of the mandible. Statistical analysis showed no significant difference in postoperative relapse. Conclusion : This study suggests that both methods of skeletal fixation investigated give comparable postoperative stability and their use in mandibular setback appears to be a fairly stable clinical procedure.

조직외적 요인이 자발적 이직에 미치는 효과 및 재직기간의 조절효과

안관영,권오석 대한경영학회 2003 大韓經營學會誌 Vol.16 No.7

Employee turnover has long been a concern of the hospitality industry because of it's high turnover rate. Thus employee turnover continues to be an important issue in both practical and theoretical spheres. Traditionally researches in voluntary turnover focus in the relationship between organizational determinants and turnover, but it's explanation power has not been high. The purpose of this paper is to review the extra-organizational determinants of voluntary turnover, and the moderating effect of tenure on the determinants and turnover. Based on the responses of 643 subjects in 30 grand hotels, empirical analysis showed that family responsibility and community support are negatively related with intention to leave, and family work conflict is affirmatively related with it. But tenure appeared to have no significant moderating effect on the relationship between determinants and intention to leave.

가방 끈 변화에 따른 보행동작 분석

김관영,오정환,최대우 忠南大學校體育科學硏究所 2006 體育科學硏究誌 Vol.24 No.1

The purpose of this research lies in examining how school bag strings influence the walking posture of middle school students, so as to prevent their waist and shoulder pains that can be caused by adjusting school bag strings inappropriately and to provide some basic information that can assist in perfect body posture education for them. Subjects with a marker on their body are asked to walk in accordance with the metronome and every subject was recorded and analyzed. The significance level of the data is chosen to be 0.05.(or equivalently, 5%) It is concluded as the following. 1) In contrast to the type D of loose string bag, there are no significant differences in the subject's stride in type B of normal bag string' length and in type C of tight string bag. 2) There is no noticeable difference of the ankle and knee angles according to the length of the bag string when the right heel touches the ground 3) The hip angle while the right heel touching the ground is the smallest in type D of loose string bag. The result as A>C>B>D shows an important effect of bag string on the hip angle. 4) When the right heel touches the ground, the anterioposterior angle of upper body is the most in type D. The result as D>B>C>A shows a noticeable effect of bag string on the angle of inclination 5) There is no significant difference in the angles of ankle, knee, hip and anterioposterior angle of head according to the length of the string when the left toe separates from the ground. 6) At the moment the left toe separates from the ground, the anterioposterior angle of upper body is the most in type D. The result as D>C>B>A shows a significant effect of bag string on it. 7) There is noticeable difference neither in the angles of ankle, knee and hip nor in the angles of anterioposterior angle according to the length of bag string when the left heel touches the ground. 8) At the moment the left heel leaves the ground, the anterioposterior angle of upper body is the most in type D. The result D>C>B>A shows an important effect of the bag string on it. 9) There is no significant difference in the angles of ankle, knee, hip and anterioposterior angle of head according to the length of bag string when the right toe leaves the ground. 10) The anterioposterior angle of upper body is the most at the moment the right toe separates from the ground. The result D>B>C>A shows a noticeable effect of bag string on it.