• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.197-200
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• 2001

반응성 스퍼터링법으로 TaN film을 증착한 후 열처리온도에 따라 TaN 박막의 $R_s$(sheet resistance) 특성을 평가하고 미세구조 변화에 따른 전기적 특성 변화를 고찰하였다. TaN 박막을 열처리한 결과 $400^{\circ}C$에서 $600^{\circ}C$까지는 (110)의 회절피크만 보이다가 $700^{\circ}C$ 에서는 (200)의 회절 피크가 나타났고 특히 as-deposition 상태와 $300^{\circ}C$ 열처리시에는 Ta와 TaN 상이 혼재한 상태로 나타났으며 전기저항 변화는 as-deposition 상태가 $140{\Omega}/{\square}$로 가장 높았으며 열처리 온도가 증가함에 따라 저항은 점차적으로 감소하다가 $600^{\circ}C$와 $700^{\circ}C$에서는 전기저항이 다시 증가하였다. $500^{\circ}C$까지는 표면 형상이나 표면조도보다는 열처리 온도의 증가에 따른 TaN 박막의 결정구조 변화가 전기저항에 영향을 주는 주 요인으로 작용하고, $600^{\circ}C$와 $700^{\circ}C$ 열처리시에 결정립의 증가에도 불구하고 전기저항이 증가하는 것은 고온 열처리에 의한 표면조도가 증가하였기 때문이라고 생각된다.

• Korean Journal of Materials Research
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• v.2 no.2
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• pp.95-100
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• 1992

The bond lengths, bond angles and energies of $C_6$ clusters are calculated by using the simulation technique based on some semiempirical potential energy functions, with the result that the equilibrium configuration of $C_6$ is a regular equilateral hexagon. The same simulations have been performed for linear and cyclic forms of $C_7-C_10$ clusters and the results show that the regular heptagonal, octagonal, nonagonal and decagonal forms are more stable than the linear forms of the respective clusters. Comparison of this result with the present author's previous result that the most stable configurations of $C_2-C_5$ are linear implies that the most stable configuration of the cluster changes from one-dimension al to two-dimensional one as the cluster size increases and that the critical cluster size is $C_6$.

• Polymer(Korea)
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• v.38 no.4
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• pp.411-416
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• 2014

Due to the polar characteristics of silica compared to carbon black, the degree of silica dispersion, which affects the mechanical properties of rubber compounds, is an important issue. Wolff first introduced the in-rubber structure of particles (${\alpha}_F$) to express the structure development in the compounds; however, with the introduction of bifunctional silanes, his theory could not explain the 3-dimensional network structure of the compounds. Later his theory was expanded to express the composite interaction parameter (in-rubber structure of the compound) (${\alpha}_C$), which included Wolff's filler-filler interaction parameter (${\alpha}_F$), however, there was no reported experimental result proving the theory. This research first experimentally expressed the in-rubber structure of the compound ${\alpha}_C$ (= ${\alpha}_F+{\alpha}_{FP}$(filler-silane-rubber interaction parameter) + ${\alpha}_P$ (rubber-rubber interaction parameter)) upon mono- and bifunctional silane treated silica filled natural rubber (NR) compounds. Using different structure silanes, i.e. PTES, OTES, TESPD, and TESPT, the ${\alpha}_C$ value of each compound was measured and calculated. The ${\alpha}_C$ value of TESPT treated silica filled compound was 1.64, which composed of ${\alpha}_F$ (0.99), ${\alpha}_{FP}$ (0.31), and ${\alpha}_P$ (0.34).

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.05a
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• pp.13-13
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• 2002

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.29-33
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• 2003

Material and electrical properties of copper-based ohmic contacts on n-type 4H-SiC were investigated for the effects of the post-annealing and the metal covering conditions. The ohmic contacts were prepared by sequential sputtering of Cu and Si layers on SiC substrate. The post-annealing treatment was performed using RTP (rapid thermal process) in vacuum and reduction ambient. The specific contact resistivity ($p_{c}$), sheet resistance ($R_{s}$), contact resistance ($R_{c}$), transfer length ($L_{T}$), were calculated from resistance (RT) versus contact spacing (d) measurements obtained from TLM (transmission line method) structure. The best result of the specific contact resistivity was obtained for the sample annealed in the reduction ambient as $p_{c}= 1.0 \times 10^{-6}\Omega \textrm{cm}^2$. The material properties of the copper contacts were also examined by using XRD. The results showed that copper silicide was formed on SiC as a result of intermixing Cu and Si layer.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.153-157
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• 2006

본 논문에서는 SoC 공정에 적용 가능한 spiral 인덕터의 특성에 대해 다루었다. 일정한 크기의 인덕터에서 턴 수의 변화에 따른 인덕턴스와 Q-factor의 변화를 보았다. HFSS 프로그램을 사용하여 턴 수와 선로의 폭이 같은 조건하에서 사각형 구조와 팔각형 구조를 갖는 인덕터의 인덕턴스와 Q-factor의 ?냅? 계산하였다. 사각형 구조와 팔각형 구조 모두 선로 폭 보다는 턴 수가 증가할수록 인덕턴스가 증가하였다. 턴 수가 증가할수록 Q-factor의 값은 사각형 구조는 감소한 반면 팔각형 구조는 증가하였다. spiral과 실리콘 사이에 PGS(Patterned Ground Shield)를 삽입하여 인덕턴스 및 Q-factor의 변화를 비교 분석하였다. 그 결과 PGS의 사용으로 사각형 구조와 팔각형 구조에서 턴 수에 따라 Q-factor의 값이 구조에 따라 서로 다른 방향으로 증감하는 것을 확인할 수 있었다.

• Journal of the Korean Magnetics Society
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• v.19 no.2
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• pp.47-51
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• 2009

The surface structure of polycrystalline Fe films of various thicknesses on glass substrates have been studied using a Ti: Sapphire laser at 780 nm. We found that the surface structure possesses C$_s$ crystal structure close to $C_{2v}$ through symmetry consideration. We present one-fold intensity profile with one mirror plane in second harmonic (SH) intensity as a proof of $C_s$ symmetry. $C_s$ and $C_{2v}$ surface symmetries usually appear at the (110) surface of a cubic diamond single crystal [1]. Therefore this surface symmetry would be related to bcc (110) growth orientation coinciding with XRD measurement. Further we treated surface normalized SH asymmetry with various thicknesses. The SH asymmetry increases with increasing of film thickness. From these results, it is observed that the surface structure of thin polycrystalline Fe film below 5 nm is almost isotropic, while in the case of the thicker Fe films, surface structure have $C_s$ symmetry structure close to $C_{2v}$.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.71-75
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• 2005

$La_{0.5}Ca_{0.5}MnO_3$ colossal magnetoresistance (CMR) powders and pellets were synthesized by sol-gel process. The structural changes were investigated by FT-IR, CP/MAS $^{13}C$ solid state NMR spectroscopy and XRD. The particle characterization, microstructure of sintered samples, and cation composition of gel powders were studied by FE-SEM/EDS, TEM and ICP-AES. The structure refinement reveals that $La_{0.5}Ca_{0.5}MnO_3$ has orthorhombic, perovskite type unit cell. The magnetic characterizations were identified through measurement of magnetic moment by VSM.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.832-835
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• 2011

최근까지 용접구조물의 피로설계는 용접품질 수준에 따라 공칭응력 또는 핫스팟 응력에 의한 S-N선 도로부터 수행하였다. 본 연구에서는 유한요소망의 크기에 덜 민감하면서 기존의 하중모드형식, 두께 효과 및 용접결합형식에 상관없는 등가구조응력(E2S2) 접근법을 이용한 Master S-N선도로부터 철도차량 대차프레임의 피로수명을 평가하고자 한다. 또한 합리적인 철도차량 용접대차프레임의 피로해석 연구일환으로서, 다축피로조건인 EN규격의 피로시험조건하에 이의 피로수명을 평가하고자 한다.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.308-319
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• 2020

In this study, the field applicability of the recently constructed multifunctional fishway in Seomunbo, Yeongcheon-si, and Gyeongsangbuk-do were examined. The analysis variables were R/C slab (S1) and R/C+S/C slab (S2), the underground passage standard areas (width × length) were 1.4 m × 0.2 m, 1.4 m × 0.3 m, and 1.4 m × 0.6 m, and the flow velocities were 0.8, 1.2, and 1.6 m/s. As a result of the analysis, the safety of the design of Seomunbo was evaluated. The analysis showed compared to the Seomoon Weir fishway, the maximum stress of S2 decreased by 24 - 32%, the bending moment of the underground passage decreased by 16 - 33%, the maximum stress of the sidewall decreased by 20 - 36%. In addition, the bending moment of the upper slab decreased by 17 - 33%, the maximum stress of the upper slab decreased by 9 - 28%, and the bending moment decreased by 19 - 33%. Complementation was required in the following percentages: 18% and 14% for the maximum stress and bending moment of the underground passage, respectively, 15% and 17% for the maximum sidewall stress and bending moment, respectively, and 11% and 16% for the upper slab maximum stress and bending moment, respectively. The results showed that S2 was superior to that of the Seomoon Weir fishway, and the underground passage size of 1.4 m × 0.3 m was superior to those of 1.4 m × 0.2 m and 1.4 m × 0.6 m, and R/C+S/C slab was superior to that of R/C slab. The findings are expected to be useful for constructing and designing the multifunctional fishway.