• 제목/요약/키워드: J$_{}$ c/

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Thioacetamide 와 피리딘계 헤테로고리 화합물 사이의 수소 결합에 대한 연구 (Hydrogen Bonding between Thioacetamide and a Series of Heterocyclic Compounds of Pyridine)

  • 박재헌;이미경;오인철;윤창주;최영상
    • 대한화학회지
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    • 제38권5호
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    • pp.345-350
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    • 1994
  • 클로로포름과 사염화탄소 속에서 티오아세트아미드(TA)와 pyridine(Py), quinoline(Qu), and acridine(Ac)간의 수소 결합에 대한 열역학적 상수들을 조사하기 위해 5$^{\circ}C$ 에서 55$^{\circ}C$까지 TA의 $v_{a^+}$ Amide II조합띠를 사용하였다. 이 조합띠는 두 개의 Lorentzian-Gauss 곱함수의 띠로 분해되며, 각각은 TA단위체 및 수소결합을 이룬 TA의 복합체임이 확인되었다. 온도 및 농도에 따른 이 조합띠의 변화로부터 TA의 수소 결합에 대한 여러가지 열역학적 상수들을 구하였다. 클로로포름에서 TA 와 pyridine, quinoline, acridine의 수소결합 엔탈피는 각각 -7.6 kJ/mol, -6.5 kJ/mol, -5.4 kJ/mol이었고, 사염화탄소에서 TA 와 pyridine, quinoline의 결합 엔탈피는 각각 -13.3kJ/mol, -12.0kJ/mol이었다.

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1,4-Dibora-2-cyclohexene 유도체들의 합성과 그 성질 (Synthesis and Properties of 1,4-Diboracyclohexene-2 Derivatives)

  • 엄재국;호동기
    • 대한화학회지
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    • 제34권5호
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    • pp.490-497
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    • 1990
  • 1,4-dibora-2-cyclohexene 고리화합물 8을 합성하기 위한 두 가지 방법이 개발되었다. 방법 i)은 1,2-bis(dichloroaluminyl)ethane을 출발물질로 하는데 이 물질은 AlCl$_2$ 부분을 BCl$_2$로 치환시켜준다. 1,2-bis(dichloroaluminyl)ethane에 결합된 염소를 BI$_3$로 교환시켜 대응되는 요오드 화합물을 얻고 이 화합물을 alkynes와 반응시켜 헤테로고리화합물 8a, b를 많이 얻었다. 방법 ii)는 B$_2$Cl$_4$를 alkynes에 부가시켜 얻어지는 염소화합물에 BI$_3$를 치환시켜 bis(diiodoboryl)ethane유도체를 얻고 이 화합물에 alkynes와 산화환원반응을 하여줌으로 8c, d를 얻는다. 요오드 유도체인 8a는 pyridine 부가물인 9a를 생성하고 또 ether와 반응하여 ethoxy 유도체인 8e를 생성시킨다. 요오드 유도체의 dimethyl amino 치환제가 8f이다. 8a-d와 AlMe$_3$를 반응시켜 대응되는 methyl유도체인 8g-j를 얻고 이들 화합물은 THF속에서 칼륨과 반응시켜 불안정한 라디칼 음이온이 생성되고 여기서 ESR 결과가 측정된다. 8g-j의 전기화학적인 실험이 비가역적인 환원반응으로 나타났다. 8g-j화합물은 (C$_5$H$_5$)CO(C$_2$H$_4$)$_2$와 반응하여 중간체인 16개 VE(valence electron)를 갖는 착물 (C$_5$H$_5$)Co(8)이 얻어지는데 이 화합물은 다시 C-H 활성화에 의해 대응되는 붉은색의 1,4-diboracyclohexene 착물 10을 생성하게 된다. 착물 10h와 10j의 X-ray 구조가 결정되었다.

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API 5LB강관의 고주파전기저항용접부에 관한 파괴인성 평가 (Evaluation of Fracture Toughness on High Frequency Electric Resistance Welded API 5LB Steel Pipe)

  • 오세욱;윤한기;안계원
    • 한국해양공학회지
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    • 제1권1호
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    • pp.127-137
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    • 1987
  • The evaluation of the elastic-plastic fracture toughness $J_{1C}$ was performed on the center of weld metal(CWM), the heat affected zone (HAZ) and the base metal (BM) of API 5LB steel pipes welded by the high frequency electric resistance welding. The $J_{1C}$ was evaluated by the JSME R-Curve and JSME SZW methods using the smooth and side-grooved specimens. The results are as follows; (1) The $J_{1C}$ values by the SZW method are overestimated as compared with those by the R-curve method, because the micro-crack is formed as SZW increase with the deformation at SZ after initiation of the ductile crack. (2) The everage of $J_{1C}$ values by the the R-curve and the SZW methods in side-grooved specimens tended to decrease in comparison with smooth specimens 9.42% at CWM, 4.2% at HAZ, 23.2% at BM, respectively. (3) The boundary of the fatigue pre-crack, stretched zone, and dimple regions appeared more clearly in side-grooved specimens, for the slight change of SZW in the direction of the plate thickness, as compared with smooth specimens.

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420J2 강의 내식성에 미치는 오스테나이트화 온도의 영향 (Effect of Austenitizing Temperatures on Corrosion Resistance of 420J2 Stainless Steel)

  • 김헌주;정병호
    • 열처리공학회지
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    • 제21권3호
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    • pp.150-156
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    • 2008
  • The effects of austenitizing temperature in a range of $1000{\sim}1150^{\circ}C$ on the corrosion resistance in 420J2 stainless steel tempered at $150^{\circ}C$ were investigated by an electrochemical uniform corrosion test in a solution of 0.5M $H_2S0_4$. Pitting test and DL-EPR test for intergranular corrosion were carried out in a solution of 3.5% NaCl and 0.5M $H_2S0_4$ + 0.01 M KSCN respectively. In uniform corrosion test, specimens austenitized below $1100^{\circ}C$ showed similar corrosion current density and passive current density, whereas specimens austenitized at $1150^{\circ}C$ showed a little higher values. Pitting potential slightly increased with an increase of austenitizing temperature. The degree of sensitization, DOS, also slightly increased with an increase of austenitizing temperature, reaching the highest degree at $1150^{\circ}C$. It was expected that the increase of DOS was due to the larger grain size rather than the dissolved precipitates in the matrix.

Reduction of Twin Pregnancy by Transvaginal Ultrasound-guided Aspiration in a Mare

  • Lee, Eun-bee;Song, Mingeun;Park, Chull-gyu;Hwang, Jun-seok;Chun, Yong-woo;Lee, Seung-hwan;Cheong, Jongtae;Lee, Joomyoung;Kang, Tae-Young;Seo, Jong-pil
    • 한국임상수의학회지
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    • 제34권4호
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    • pp.304-306
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    • 2017
  • A 3-year-old Thoroughbred mare was referred to J&C Equine Hospital with gestation day 30 twin pregnancy. On transrectal ultrasonographic examination, two similar sized (28 mm) embryonic vesicles, unilaterally fixed in the uterine horn, were detected. Transvaginal ultrasound-guided aspiration (TUGA) was performed for reduction of one embryonic vesicle. Yolk sac and allantoic cavity fluids from one embryonic vesicle were aspirated by a needle guided by using transvaginal ultrasound. The mare continued normal singleton pregnancy after twin reduction and delivered a foal successfully. This is the first case described the clinical use of TUGA in Korea. Clinical use of TUGA in twin reduction after embryonic fixation is recommended for equine clinicians.

TEM study on a-axis outgrowth formation in c-axis oriented YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin films

  • Hahn, T.S.;Hong, K.S.;Kim, C.H.
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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    • pp.51-55
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    • 2000
  • Using modified melt-textured grown targets, YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin films were prepared by pulsed laser deposition technique at the laser energy density from 1 J/cm$_2$ to 4 J/cm$_2$. All the films showed c-axis preferred orientations, however, a-axis outgrowths on the film surface were considerably increased with an increase of the laser energy density. To examine the origin of the a-axis outgrowth formation, the microstructures of films deposited at 2 J/cm$_2$ and 4 J/cm$_2$ were investigated using X-ray diffraction, transmission electron microscopy, and high-resolution electron microscopy. It was shown that a significant number of Y$_2$O$_3$ inclusions were formed during the growth of c-axis oriented films at 4 J/cm$_2$. These inclusions formed nucleation sites for the a-axis outgrowths. It is considered that, due to the unstable growth conditions with a high flux density of incident vapor species and the strain induced by the surrounding c-axis films, the Y$_2$O$_3$ inclusions would prefer the nucleation of α-axis grains.

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소아(小兒)에 있어 교정전후에 악골의 변화(變化)에 관(關)한연구(2차보고) (FACIAL GROWTH CHANGE AFTER ORTHODONTIC TREATMENT IN CHILDREN (Second Report))

  • 손동수
    • 대한소아치과학회지
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    • 제11권1호
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    • pp.7-12
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    • 1984
  • This study was undertaker to observe the longitudinal change by orthodontic treatment for early Class III malocclusion in primary and mixed dentition. Cephalometric roentgenograms of 8 children with Class III malocclusion obtained during activator therapy were measured and compared with those obtained before activator therapy. The following results were observed. During treatment with activator; 1. The maxilla became retrueded in A,C,E, and K and protruded in F, G, H, and J. 2. The mandible became retruded in A,C,E, and F and F and protruded in H and J. No difference was observed in G and K. 3. Gonial angle became reduced in A,C,E,F, and K and increased in H. No difference was observed in G and J. 4. The steepness of mandibular plane became reduced in C,E,F,G,H, and J and increased in A. No difference was observed in K. 5. The inclination of upper incisor became more labially in A,C,E,G,H,J, and K. No difference was observed in F. 6. The inclination of lower incisor became more lingually in all cases.

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배관에 존재하는 원주방향 표면균열에 대한 파괴거동 해석 (ll) - 유한요소해석을 통한 검증 - (Fracture Behavior Estimation for Circumferential Surface Cracked Pipes (ll) - Finite Element Validation -)

  • 김진수;김윤재;김영진
    • 대한기계학회논문집A
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    • 제26권1호
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    • pp.139-146
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    • 2002
  • This paper provides validations of the reference stress based J and $C^{*}$ estimations, proposed in Part I, for inner, circumferential surface cracked pipes under internal pressure and global bending against detailed 3-D elastic-plastic and elastic-creep FE results. For this purpose, actual tensile properties of two typical stainless steels (TP304 and TP316) are used for elastic-plastic FE analyses and two realistic creep laws are used for elastic-creep FE analyses. For a total of twenty cases considered in this paper, agreements between the proposed reference stress based J and $C^{*}$ estimations and the FE results are excellent. More important aspect of the proposed estimations is that they can be used to estimate J and $C^{*}$ not only at the deepest point of the surface crack but also at an arbitrary point along the crack front.front.

비선형 파괴역학 해석을 위한 새로운 기법: 개선된 참조 응력법 (New Engineering Method for Non-Linear Fracture Mechanics Analysis Enhanced Reference Stress Method)

  • 김윤재;김영진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.17-25
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    • 2001
  • This paper briefly describes the new engineering method, called the enhanced reference stress method, to estimate J (or $C^*$) for non-linear fracture mechanics analysis of defective components, recently proposed by authors. The proposed method offers significant advantages over existing methods in terms of its accuracy, simplicity and robustness. Examples of application of the proposed method to typical piping integrity problems such as through-wall cracked pipes under combined loading, and surface cracked pipes under internal pressure and bending are given. Excellent agreements between the FE J and $C^*$ results and those of the proposed method provide sufficient confidence in the use of the proposed method. One notable point is that the proposed method can be used to estimate J (or $C^*$) along the crack front of surface cracks. Moreover simplicity of the proposed method makes it easy to extend to more complex problems. Thus the proposed method is attractive to assess the significance of defects under practical situations.

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배관 원주방향 표면균열에 대한 탄소성 파괴 파라미터의 예측 (II) (Engineering Estimation of Elastic-Plastic Fracture Parameter for Circumferential Surface Cracked Pipes: Part II)

  • 김윤재;김진수;김영진;박윤원
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.310-315
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    • 2001
  • This paper provides validations of the reference stress based J and $C^*$ estimations, proposed in Part I, for inner, circumferential surface cracked pipes under internal pressure and global bending against detailed 3-D elastic-plastic and elastic-creep FE results. For this purpose, actual tensile properties of two typical stainless steels (TP304 and TP316) are used for elastic-plastic FE analyses and two realistic creep laws are used for elastic-creep FE analyses. For a total of twenty cases considered in this paper, agreements between the proposed reference stress based J and $C^*$ estimations and the FE results are excellent. More important aspect of the proposed estimations is that they can be used to estimate J and $C^*$ not only at the deepest point of the surface crack but also at an arbitrary point along the crack front.

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