• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.864-871
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• 2016

This study was conducted to compare and analyze gross calorific values from measurement methods of lignocellulosic biomass and calculation data from calorific value prediction models based on the elemental content. The deviation of Liriodendron tulipifera (LT) and Populus euramericana (PE) was shown 7.7 cal/g and 7.4 cal/g respectively in palletization method, which are within repeatability limit 28.8 cal/g of ISO FDIS 18125. In the case of Thailand charcoal (TC), nontreatment method and palletization method was satisfied with repeatability limit as 22.8 cal/g and 8.8 cal/g respectively. Seowon charcoal (SC) was shown deviation of 11.4 cal/g in nontreatment method, because the density and chemical affinity of sample increases as the carbon content increases from heat treatment at high temperature in the case of TC and SC. In addition, after applying the elemental content of each of these samples to the calorific value prediction models, the study found that Model Equation (3) was relatively consistent with measured calorific values of all these lignocellulosic biomass. Thus, study about the correlation between the density and size of particle should be conducted in order to select the measurement method for a wide range of solid biofuels in the future.

• Journal of information and communication convergence engineering
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• 제15권3호
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• pp.193-198
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• 2017

In this study, we propose a three-dimensional (3D) visualization technique of occluded objects using integral imaging with a plenoptic camera. In previous studies, depth map estimation from elemental images was used to remove occlusion. However, the resolution of these depth maps is low. Thus, the occlusion removal accuracy is not efficient. Therefore, we use a plenoptic camera to obtain a high-resolution depth map. Hence, individual depth map for each elemental image can also be generated. Finally, we can regenerate a more accurate depth map for 3D objects with these separate depth maps, allowing us to remove the occlusion layers more efficiently. We perform optical experiments to prove our proposed technique. Moreover, we use MSE and PSNR as a performance metric to evaluate the quality of the reconstructed image. In conclusion, we enhance the visual quality of the reconstructed image after removing the occlusion layers using the plenoptic camera.

• Structural Engineering and Mechanics
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• 제62권3호
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• pp.345-355
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• 2017

The aim of the present study is to develop an elemental approach based on the differential quadrature method for free vibration analysis of cracked thin plate structures. For this purpose, the equations of motion are established using the classical plate theory. The well-known Generalized Differential Quadrature Method (GDQM) is utilized to discretize the governing equations on each computational subdomain or element. In this method, the differential terms of a quantity field at a specific computational point should be expressed in a series form of the related quantity at all other sampling points along the domain. However, the existence of any geometric discontinuity, such as a crack, in a computational domain causes some problems in the calculation of differential terms. In order to resolve this problem, the multi-block or elemental strategy is implemented to divide such geometry into several subdomains. By constructing the appropriate continuity conditions at each interface between adjacent elements and a crack tip, the whole discretized governing equations of the structure can be established. Therefore, the free vibration analysis of a cracked thin plate will be provided via the achieved eigenvalue problem. The obtained results show a good agreement in comparison with those found by finite element method.

• 분석과학
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• 제18권4호
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• pp.263-270
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• 2005

핵분열트랙은 우라늄, 플루토늄, 토륨 등의 방사성핵종 분석이나, 리튬이나 붕소와 같이 열중성자와 핵반응을 하는 원소분석에 매우 유용하다. 이 방법은 대기 중의 방사성핵종 분석을 통해 핵무기 실험을 검출한다거나, 우주공간의 중이온에 대한 선량측정이나 운석의 우주선 조사과정 추정, 원자력분야의 핵분열률 측정, 암석의 연대 및 역사를 파악하거나, tracer로 사용하는 등 여러 분야에 적용 가능하다. 현재 원자력연구소에서는 알파트랙기입법을 이용한 미량의 보론 분석이나, 핵분열트랙을 이용한 우라늄 등의 핵물질을 포함한 입자분석에 적용하고 있다. 본 총설에서는 트랙형성의 이론적 배경, 에칭된 트랙을 얻는 실제 과정 및 앞으로의 전망 등에 대해 살펴보았다.

• Journal of the Korean Wood Science and Technology
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• 제35권1호
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• pp.36-43
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• 2007

보존처리를 위한 사전 조사 일환으로 충북 영동군 영국사 대웅전 하부에서 출토된 탄화 목부재의 재질을 원소분석(C, O, H, N, S), SEM-EDX, X선 회절 및 IR 분석을 이용하여 조사하였다. 원소분석 결과, $500^{\circ}C$ 정도에서 탄화된 것을 알 수 있었다. SEM-EDX분석에서 칼슘 성분이 다량 검출되었다. 이는 토양에서 흡수된 것으로 보인다. X선 회절 및 IR분석에서는 셀룰로오스 결정성이 붕괴되고 목재 성분이 탄화정도에 따라 다른 수준으로 열분해된 것이 확인되었다. 이상의 재질 분석 결과, 수용성 PEG (polyethylene glycol)의 분자량을 달리하는 2단계 보존처리하는 방법이 영국사 대웅전 출토 탄화목의 적절 보존법으로 사료되었다.

• 대한금속재료학회지
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• 제50권1호
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• pp.28-33
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• 2012

Ball-milled Ni-Al powder compacts have been synthesized by the heat of molten cast iron and have been coated on cast iron. The effects of the ball-milling time on the microstructure of the intermetallic coatings have been investigated. The experimental results showed that the ball-milled Ni-Al powder compacts were completely reacted and were successfully coated on the cast iron without re-melting the substrate. Densification of the coating layers was enhanced by increasing the ball-milling time. This might be attributed to the fact that the heat released during the intermetallic reaction was dispersed over a prolonged reaction time by the ball-milling of the elemental powders.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.231-235
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• 2014

Rh doped Ni and Co catalysts, Rh-M/$CeO_2$(20 wt %)-$Al_2O_3$ (0.2 wt % of Rh; M = Ni or Co, 20 wt %) were synthesized to produce hydrogen via autothermal reforming (ATR) of commercial gasoline at $700^{\circ}C$ under the conditions of a S/C ratio of 2.0, an O/C ratio of 0.84, and a gas hourly space velocity (GHSV) of $20,000h^{-1}$. The Rh-Ni/$CeO_2$(20 wt %)-$Al_2O_3$ catalyst (1) exhibited excellent activities, with $H_2$ and ($H_2$+CO) yields of 2.04 and 2.58 mol/mol C, respectively. In addition, this catalyst proved to be highly stable over 100 h without catalyst deactivation, as evidenced by energy dispersive spectroscopy (EDX) and elemental analyses. Compared to 1, Rh-Co/$CeO_2$(20 wt %)-$Al_2O_3$ catalyst (2) exhibited relatively low stability, and its activity decreased after 57 h. In line with this observation, elemental analyses confirmed that nearly no carbon species were formed at 1 while carbon deposits (10 wt %) were found at 2 following the reaction, which suggests that carbon coking is the main process for catalyst deactivation.

• 대한치과기공학회지
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• 제31권1호
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• pp.55-61
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• 2009

Passive fitting of meso-structure and super-structures is a predominant requirement for the longevity and clinical success of osseointegrated dental implants. However, precision and passive fitting has been unpredictable with conventional methods of casting as well as for corrective techniques. Alternative to conventional techniques, electro discharge machining(EDM) is an advanced method introduced to dental technology to improve the passive fitting of implant prosthesis. In this technique material is removed by melting and vaporization in electric sparks. Regarding the efficacy of EDM, the application of this technique induces severe surface morphological and elemental alterations due to the high temperatures developed during machining, which vary between $10,000{\sim}20,000^{\circ}C$. The aim of this study was to investigate the morphological and elemental alterations induced by EDM process of casting dental gold alloy and non-precious alloy used for the production of implant-supported prosthesis. A conventional clinical dental casting alloys were used for experimental specimens patterns, which were divided in three groups, high fineness gold alloy(Au 75%, HG group), low fineness gold alloy(Au 55%, LG group) and nonprecious metal alloy(Ni-Cr, NP group). The UCLA type plastic abutment patterns were invested with conventional investment material and were cast in a centrifugal casting machine. Castings were sandblasted with $50{\mu}m\;Al_2O_3$. One casting specimen of each group was polished by conventional finishing(HGCON, LGCON, NPCON) and one specimen of each group was subjected to EDM in a system using Cu electrodes, kerosene as dielectric fluid in 10 min for gold alloy and 20 min for Ni-Cr alloy(HGEDM. LGEDM, NOEDM). The surface morphology of all specimens was studied under an energy dispersive X-ray spectrometer (EDS). The quantitative results from EDS analysis are presented on the HGEDM and LGEDM specimens a significant increase in C and Cu concentrations was found after EDM finishing. The different result was documented for C on the NPEDM with a significant uptake of O after EDM finishing, whereas Al, Si showed a significant decrease in their concentrations. EDS analysis showed a serious uptake of C and Cu after the EDM procedure in the alloys studied. The C uptake after the EDM process is a common finding and it is attributed to the decomposition of the dielectric fluid in the plasma column, probably due to the development of extremely high temperatures. The Cu uptake is readily explained from the decomposition of Cu electrodes, something which is also a common finding after the EDM procedure. However, all the aforementioned mechanisms require further research. The clinical implication of these findings is related with the biological and corrosion resistance of surfaces prepared by the EDM process.

• 대한수의학회지
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• 제43권3호
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• pp.423-428
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• 2003

진흙버섯 품종별 P. linteus, P. baumii 그리고 P. gilvus에 대한 형태학적 차이, 일반성분 및 무기성분을 조사하였다. 전자현미경 사진에서 P. gilvus와 P. linteus는 비슷한 형태를 보여주고 있다. 원소 함량의 구성비에서는 세 종류의 버섯이 모두 유사함을 보여주었다. 일반성분을 분석 비교시 수분의 함량은 P. baumii가 가장 높았으며 P. gilvus의 수분 함량은 10% 이내로 낮은 경향을 보여주었다. 식이섬유는 약 30% 이상을 함유하고 있으나 vitamin C 및 단백질의 함량은 높지 않았다. 원소분석에서 Ca의 경우 세 종류의 진흙버섯에서 P. baumi가 가장 높은 Ca 함량을 보여주었으나 통계적유의성은 없었다. 그러나 원소조성 및 일반성분 비교에서는 P. linteus, P. baumii 그리고 P. gilvus의 큰 차이점이 나타나지 않았다.

• 자원리싸이클링
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• 제21권5호
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• pp.31-37
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• 2012

실리콘 웨이퍼공정에서 발생하는 실리콘 슬러지로부터 실리콘 및 탄화규소를 분리한 다음, 전해법으로 원소형태의 실리콘을 회수하는 연구를 수행하였다. 실리콘 슬러지의 주요 불순물은 절삭유, 금속불순물, 실리콘 및 실리콘 카바이드를 들 수 있다. 기계적 선별법으로 분리한 실리콘, 탄화실리콘 복합물을 $1000^{\circ}C$에 1시간동안 염화 배소하여 응축하고 회수한 사염화실리콘을 이온성액체인 $[Bmpy]Tf_2N$에 용해하여 전해액으로 사용하였다. 순환전위법으로부터 $[Bmpy]Tf_2N$의 안정한 전압구간과 사염화실리콘을 용해한 $[Bmpy]Tf_2N$ 전해액에서 실리콘의 환원으로 추정되는 환원피크를 얻을 수 있었다. 정전위법(-1.9 V vs. Pt-QRE)에서 1시간동안 금 전극 상에 전해한 다음, 전극표면을 XRD, SEM-EDS 및 XPS 분석을 통하여 실리콘이 원소형태로 전착되었음을 확인하였으며, 미량의 산소가 검출되는 것은 분석과정에서 시편이 공기 중에 노출되었기 때문으로 판단된다.