• Journal of the Korean Wood Science and Technology
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• 제44권3호
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• pp.430-439
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• 2016

한약재 찌꺼기로 제조한 한방보드로부터 방출되는 향기성분을 Tenax 튜브에 흡착시킨 후 TD GC/MS에 의해 동정하고, 온도에 따른 방출특성을 검토하였다. 한방보드로부터 방출되는 휘발성 물질로는 88종이 동정되었다. 온도별로는 $25^{\circ}C$에서 44종, $35^{\circ}C$에서는 55종, $45^{\circ}C$에서는 65종이 검출되었으며, 온도가 상승함에 따라 화합물의 수와 전체피크 면적 모두 증가하였으며, 측정한 모든 온도조건에서 검출된 향기성분은 34종이었다. $25^{\circ}C$에서 검출된 향기성분의 93%, $35^{\circ}C$에서는 92%, $45^{\circ}C$에서는 90%가 Hydrocarbon류의 화합물이었으며, 그 외 Ether류가 약 4%, Ketone, Aldehyde, Acid류의 물질이 소량 검출되었다. Hydrocarbons에는 17종, 11%가 monoterpenes이며, 80%, 39종이 sesquiterpenes이었다. monoterpenes에는 limonene이 가장 많이 검출되었으며, sesquiterpene류의 주요 향기 물질로는 ${\alpha}-curcumene$, zingiberene, ${\beta}-elemene$, ${\beta}-selinene$, ${\alpha}-amorphene$, ${\alpha}-copaene$이었다. 특히 ether화합물인 anethole (3.26%)이 모든 온도에서 비교적 많이 검출되었다. 이상의 결과에서 한약재 찌꺼기로 제조한 한방보드에는 다양한 종류의 향기성분이 다량 포함되어 있으며, 향기성분을 활용한 다양한 제품의 제조에 활용할 수 있을 것으로 생각된다.

• Journal of the Korean Wood Science and Technology
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• 제33권6호통권134호
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• pp.71-78
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• 2005

임산바이오매스 자원 이용의 일환으로 율추(栗皺) 열수추출물의 디에틸에테르 가용부 및 초산에틸 가용부로부터 칼럼크로마토그래피 등을 이용하여 3종의 물질을 단리하여 화학구조를 동정한 결과, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid 그리고 (+)-catechin을 확인하였다. 이들 단리화합물의 항산화활성을 DPPH 라디칼 전자공여능(EDA)으로 측정한 결과, 10 ppm에서 화합물 3,4,5-trihydroxybenzoic acid (gallic acid)와 (+)-catechin은 대조구인 ascorbic acid와 $\alpha$-tocopherol 보다 높게 나타났고, 특히 화합물 gallic acid는 ascorbic acid보다 약 21배, $\alpha$-tocopherol보다 약 6배 높게 나타났으며 화합물 catechin보다 약 2.7배 높게 나타났다.

• Structural Engineering and Mechanics
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• 제16권1호
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• pp.35-46
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• 2003

The histories and distributions of dynamic stresses in an orthotropic hollow cylinder under sinusoidal impact load are obtained by making use of eigenfunction expansion method in this paper. Dynamic equations for axially symmetric orthotropic problem are founded and results are carried out for a practical example in which an orthotropic hollow cylinder is in initially at rest and subjected to a dynamic interior pressure $p(t)=-{\sigma}_0(sin{\alpha}t+1)$. The features of the solution appear the propagation of the cylindrical waves. The other hand, a dynamic finite element solution for the same problem is also got by making use of structural software (ABAQUS) program. Comparing theoretical solution with finite element solution, it can be found that two kinds of results obtained by two different solving methods are suitably approached. Thus, it is further concluded that the method and computing process of the theoretical solution are effective and accurate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.709-710
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• 2008

In this paper, we calculated permanent magnetic linkage flux ${\psi}_{\alpha}$ and Ld, Lq parameters of IPMSM and compared two model which has different barrier width. IPMSM has two kinds of torque that reluctance torque and magnetic torque. In constant torque region, using the Maxwell stress tensor method, we calculated the torque and current phase angle ${\beta}$ which has appeared maximum torque. In weakening flux region, we calculated the current phase angle ${\beta}$ which flux ${\psi}_o$ lower than limited flux ${\psi}_{omax}$. From the current phase angle ${\beta}$, we calculated torque by torque equation and compared two model characteristic.

• 한국안전학회지
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• 제18권3호
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• pp.46-53
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• 2003

For the tensile tests of the F.E.M., microvoids are created by the boundary separation process at the martensite boundary or neighborhood and at inclusions within the fracture. to grow to the ductile dimple fracture. For the case of the M.E.F., microvoids created at the discontinuities of the martensite phase which exists at the grain boundary of the primary ferrite are grown to coalescence with the cleavage cracks induced at the interior of the ferrite, which as a result show the discontinuous brittle fracture behavior. In spite of their similar tensile strengths, the fatigue limit and the notch sensitivity of the M. E.F. is superior to those of the F.E.M., The M.E.F. is much more insensitive to notch than F.E.M. from the stress concentration factor($\alpha$).

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.198-204
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• 1994

Chemical shifts in aqueous sodium dodecylsulfate(SDS) micellar solution solublizing phenol, catechol, resorcinol, hydroquinone have been measured to investigate solubilization properties. Proton nuclear magnetic resonance frequencies of solubilizates as well as those of the ${\alpha}$-methylene, middle methylene and terminal methyl of SDS shift linearly as a function of solubilizate concentration. From the plots of observed chemical shift (v) vs solubilizate concentration, slope (a) and solubilizate free chemical shift ($v_0$) are obtained. They are very informative to solubilization site of the systems. Catechol and phenol solubilized SDS and catechol solubilized dodecylpyridinium chloride(DPC), dodecyltrimethylammonium bromide(DTAB) systems are studied using the same method to compare head group effect and middle methylene proton signal splitting. It is proposed that phenol and catechol are inserted into micellar interior and the number of methylenes assigned to the higher field peaks is 5.0${\pm}$0.5.

• 천문학회지
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• 제47권6호
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• pp.259-277
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• 2014

G192.8-1.1 has been known as one of the faintest supernova remnants (SNRs) in the Galax until the radio continuum of G192.8-1.1 is proved to be thermal by Gao et al. (2011). Yet, the nature of G192.8-1.1 has not been fully investigated. Here, we report the possible discovery of faint non-thermal radio continuum components with a spectral index ${\alpha}{\sim}0.56(S_{\nu}{\propto}{\nu}^{-{\alpha}})$ around G192.8-1.1, while of the radio continuum emission is thermal. Also, our Arecibo $H_I$ data reveal an $H_I$ shell, expanding with an expansion velocity of $20-60km\;s^{-1}$, that has an excellent morphological correlation with the radio continuum emission. The estimated physical parameters of the $H_I$ shell and the possible association of non-thermal radio continuum emission with it suggest G192.8-1.1 to be an~0.3 Myr-old SNR. However, the presence of thermal radio continuum implies the presence of early-type stars in the same region. One possibility is that a massive star is ionizing the interior of an old SNR. If it is the case, the electron distribution assumed by the centrally-peaked surface brightness of thermal emission implies that G192.8-1.1 is a "thermal-composite" SNR, rather than a typical shell-type SNR, where the central hot gas that used to be bright in X-rays has cooled down. Therefore, we propose that G192.8-1.1 is an old evolved thermal-composite SNR showing recurring emission in the radio continuum due to a nearby massive star. The infrared image supports that the $H_I$ shell of G192.8-1.1 is currently encountering a nearby star forming region that possibly contains an early type star(s).

• 열처리공학회지
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• 제12권3호
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• pp.221-230
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• 1999

The surface nitrogen permeation of Al alloyed 0.14%C-13%Cr stainless steels was investigated after heat treating at $1050^{\circ}C{\sim}1150^{\circ}C$ in the nitrogen gas atmosphere. The strong affinity between Al and nitrogen permeates the nitrogen through the interior of the steels. Two precipitates of round type and needle type are observed at the surface layer. These precipitates mainly consist of AlN containing plenty of aluminum. The surface layer of 0.53%Al alloyed specimen shows ferrite phase, while the surface layers of 1.65%Al and 2.27%Al alloyed specimens appear ${\gamma}$ plus ${\alpha}$ phases. The depth of nitrogen permeation depends upon the Al content and microstructure of the matrix. The 1.65%Al alloyed specimen representing ${\alpha}+{\gamma}$ matrix phases at the nitrogen permeation temperature shows the maximum case depth in this experiment. Although the surface hardness increases by raising the Al content of the specimen owing to the increase of nitride precipitation density, the nitride precipitation deteriorates the corrosion resistance in the solution of HCl, $H_2SO_4$, and $FeCl_3$.

• 한국분말재료학회지
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• 제25권4호
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• pp.340-345
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• 2018

Additive manufacturing by electron beam melting is an affordable process for fabricating near net shaped parts of titanium and its alloys. 3D additive-manufactured parts have various kinds of voids, lack of fusion, etc., and they may affect crack initiation and propagation. Post process is necessary to eliminate or minimize these defects. Hot isostatic pressing (HIP) is the main method, which is expensive. The objective of this paper is to achieve an optimum and simple post heat treatment process without the HIP process. Various post heat treatments are conducted for the 3D-printed Ti-6Al-4V specimen below and above the beta transus temperature ($996^{\circ}C$). The as-fabricated EBM Ti-6Al-4V alloy has an ${\alpha}^{\prime}$-martensite structure and transforms into the ${\alpha}+{\beta}$ duplex phase during the post heat treatment. The fatigue strength of the as-fabricated specimen is 400 MPa. The post heat treatment at $1000^{\circ}C/30min/AC$ increases the fatigue strength to 420 MPa. By post heat treatment, the interior pore size and the pore volume fraction are reduced and this can increase the fatigue limit.

• 한국소음진동공학회논문집
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• 제25권3호
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• pp.141-149
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• 2015

In this study, there is an investigation about the sound quality of automotive horn that attached to luxury sedans. In order to define a questionnaire of horn sound quality the factor analysis is conducted. Ten automotive horns are selected for this research and ten passenger cars(nine is luxury sedan and one economy class car). Luxury is used for the questionnaire as an attribute for the sound quality of car horn. The interior noises for ten test cars are recorded and used for the subjective analysis of car horn sound. In the paper, new sound metric for the car horn sound is presented. The new sound metric is used for the objective sound index for the prediction of subjective sound quality of car horn.