• 한국식품과학회지
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• 제35권6호
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• pp.1104-1109
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• 2003

초임계 이산화탄소를 이용하여 감귤박으로부터 ${\beta}$-cryptoxanthin을 포함한 carotenoids의 추출수율을 극대화하기 위하여, 주요 요인 변수인 추출 압력, 추출시간, 보조용매의 농도 등 추출 조건을 반응표면분석법에 의해 최적화하였다. Total carotenoids와 ${\beta}$-cryptoxanthin의 추출수율에 대한 반응표면 회귀방정식의 $R^2$는 각각 0.9789과 0.9796이었고, 1% 이내의 수준에서 유의성이 인정되었다. 추출조건에 따라 예측된 정상점은 안장점이었으며 능선분석을 실시한 결과 total carotenoids과 ${\beta}$-cryptoxanthin의 최대 추출수율은 각각 61.1%와 95.8%로 예측되었으며, 이 때의 추출 압력, 추출시간, ethanol의 농도는 각각 33.4MPa/39.6min/18.6%와 37.3 MPa/41.0 min/17.0%이었다. Total carotenoids의 추출수율은 추출 압력의 증가에 따라 증가하였지만 압력이 높을수록 일정한 값에 도달하는 경향을 보인 반면, 추출시간과 보조용매의 농도 증가에 따라 연속적으로 증가하였다. ${\beta}-Cryptoxanthin$의 추출수율은 추출 압력, 추출시간, 보조용매의 농도 증가에 따라 연속적으로 증가하였다. 감귤박으로부터 carotenoids의 추출에는 추출시간과 보조용매의 농도 사이의 상호작용이 중요한 역할을 하였다.

• 한국해양공학회지
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• 제16권6호
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• pp.60-64
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• 2002

This paper describes the machining characteristics of the MoSi$_2$--based composites through the process of electric discharge drilling with various tubular electrodes. In addition to hardness characteristics, microstructures of Nb/MoSi$_2$laminate composites were evaluated from the variation of fabricating conditions, such as preparation temperature, applied pressure, and pressure holding time. MoSi$_2$-based composites have been developed in new materials for jet engines of supersonic-speed airplanes and gas turbines for high-temperature generators. These high performance engines may require new hard materials with high strength and high temperature-resistance. Also, with the exception of grinding, traditional machining methods are not applicable to these new materials. Electric discharge machining (EDM) is a thermal process that utilizes a spark discharge to melt a conductive material. The tool electrode is almost -unloaded, because there is n direct contact between the tool electrode and the work piece. By combining a non-conducting ceramic with more conducting ceramic, it was possible to raise the electrical conductivity. From experimental results, it was found that the lamination from Nb sheet and MoSi$_2$ powder was an excellent strategy to improve hardness characteristics of monolithic MoSi$_2$. However, interfacial reaction products, like (Nb, Mo)SiO$_2$and Nb$_2$Si$_3$formed at the interface of Nb/MoSi$_2$, and increased with fabricating temperature. MoSi$_2$composites, with which a hole drilling was not possible through the conventional machining process, enhanced the capacity of ED-drilling by adding MbSi$_2$, relative to that of SiC or ZrO$_2$reinforcements.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
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• pp.21-21
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• 2010

(Ba,Sr)$TiO_3$ (BST) thin film with a perovskite structure has potential for the practical application in various functional devices such as nonvolatile-memory components, capacitor, gate insulator of thin-film transistors, and electro-optic devices for display. Normally, the BST thin films derived from sol-gel and sputtering are amorphous or partially crystalline when processed below $600^{\circ}C$. For the purpose of integrating BST thin film directly into a Si-based read-out integrated circuit (ROIC), it is necessary to process the BST film below $400^{\circ}C$. The microstructural and electrical properties of low-temperature crystallized BST film were studied. The BST thin films have been fabricated at $350^{\circ}C$ by UV-assisted rapidly thermal annealing (RTA). The BST films are in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss, low leakage current density, and high breakdown voltage. Photoexcitation of the organics contained in the sol-gel-derived films by high-intensity UV irradiation facilitates elimination of the organics and formation of the single-crystalline phase films at low temperatures. The amorphous BST thin film was transformed to a highly (h00)-oriented perovskite structure by high oxygen pressure processing (HOPP) at as low as $350^{\circ}C$. The dielectric properties of BST film were comparable to (or even better than) those of the conventionally processed BST films prepared by sputtering or post-annealing at temperature above $600^{\circ}C$. When external pressure was applied to the well-known contractive BST system during annealing, the nucleation energy barrier was reduced; correspondingly, the crystallization temperature decreased. The UV-assisted RTA and HOPP, as compatible with existing MOS technology, let the BST films be integrated into radio-frequency circuit and mixed-signal integrated circuit below the critical temperature of $400^{\circ}C$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.111-114
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• 2005

Experimental and numerical studies were carried out in order to investigate the processability and the transcriptability of the injection molding of micro structures. For this purpose, we designed a mold insert having micro rib patterns on a relatively thick base part. Mold insert has a base of 2mm thickness, and has nine micro ribs on that base plate. Width and height of the rib are $300{\mu}m\;and\;1200{\mu}m$, respectively. We found a phenomenon similar to 'race tracking', due to 'hesitation' in the micro ribs. As the melt flows, it starts to cool down and melt front located in the ribs near the gate cannot penetrate further because the flow resistance is large in that almost frozen portion. When the base is totally filled, the melt front away from the gate is not frozen yet. Therefore, it flows back to the gate direction through the ribs. Consequently, transcriptability of the rib far from the gate is better. We also verified this phenomenon via numerical simulation. We further investigated the effects of processing conditions, such as flow rate, packing time, packing pressure, wall temperature and melt temperature, on the transcriptability. The most dominant factor that affects the flow pattern and the transcriptability of the micro rib is flow rate. High flow rate and high melt temperature enhance the transcriptability of micro rib structure. High packing time and high packing pressure result in insignificant dimensional variations of the rib. Numerical simulation also confirms that low flow rate causes a short shot of micro ribs and high wall temperature helps the filling of the micro ribs.

• Journal of Ginseng Research
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• 제38권1호
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• pp.22-27
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• 2014

Background: Research has been conducted with regard to the development of methods for improving the pharmaceutical effect of ginseng by conversion of ginsenosides, which are the major active components of ginseng, via high temperature or high-pressure processing. Methods: The present study sought to investigate the anticancer effect of heat-processed American ginseng (HAG) in human gastric cancer AGS cells with a focus on assessing the role of apoptosis as an important mechanistic element in its anticancer actions. Results and Conclusion: HAG significantly reduced the cancer cell proliferation, and the contents of ginsenosides Rb1 and Re were markedly decreased, whereas the peaks of less-polar ginsenosides [20(S,R)-Rg3, Rk1, and Rg5] were newly detected. Based on the activity-guided fractionation of HAG, ginsenoside 20(S)-Rg3 played a key role in inducing apoptosis in human gastric cancer AGS cells, and it was generated mainly from ginsenoside Rb1. Ginsenoside 20(S)-Rg3 induced apoptosis through activation of caspase-3, caspase-8, and caspase-9, as well as regulation of Bcl-2 and Bax expression. Taken together, these findings suggest that heat-processing serves as an increase in the antitumor activity of American ginseng in AGS cells, and ginsenoside 20(S)-Rg3, the active component produced by heat-processing, induces the activation of caspase-3, caspase-8, and caspase-9, which contributes to the apoptotic cell death.

• 대한금속재료학회지
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• 제50권11호
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• pp.861-866
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• 2012

A dense nanostructured TiN-AlN composite was prepared from high-energy ball milled TiN-AlN mixture powders by pulsed current activated sintering (PCAS). A highly dense TiN-AlN bulk composite was obtained within 2 minutes at $1500^{\circ}C$ with the simultaneous application of 80 MPa pressure and pulsed current. The fine crystalline structure of the TiN-AlN mixture, which was obtained by high-energy milling, was effectively maintained during PCAS and resulted in the enhancement of the mechanical properties. The micro hardness and fracture toughness of TiN-AlN composite were $1780kg/mm^2$ and $5MPa.m^{1/2}$, respectively. The mechanical properties were higher than monolithic AlN or TiN.

• 산업식품공학
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• 제15권3호
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• pp.209-213
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• 2011

대두에서 산패취를 발생시키는 lipoxygenase 효소를 비가열 전처리 방법인 초고압 처리 방법을 이용하여 효소의 활성도의 변화를 확인하였다. 연구 결과 초고압 처리에 의해 lipoxygenase 효소의 활성도가 감소하는 것을 확인하였다. 또한 lipoxygenase 효소의 활성도 감소에 의해 대두의 저장성에 미치는 영향을 확인하기 위해 국산 대두와 연해주대두를 이용하여 저장 실험을 실시하였다. 실험 결과 국산대두의 경우 초고압 처리에 의해 lipoxygenase 효소의 활성도가 감소하였으나 TBA가에 영향을 주는 자동산화등의 화학반응에 의해 TBA가가 지속적으로 증가함을 보여주었다. 그러나 연해주 대두의 경우에는 초고압 처리를 한 시료의 TBA가의 증가정도가 상대적으로 낮게 측정된 것을 확인하였다. 이는 연해주 대두가 항산화 성분을 국산콩에 비하여 많이 포함하고 있어 초고압 처리에 의한 lipoxygenase 효소의 불활성과 함께 항산화 성분의 영향으로 TBA가의 저장 중 증가 정도가 낮게 측정된 것으로 판단되어진다.

• 한국유기농업학회지
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• 제10권1호
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• pp.35-47
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• 2002

양돈생산에 있어 영양소의 이용율을 증대시키는 것은 절대적으로 필요하다. 가공기술(예를 들면 분쇄, 펠렛팅, 스팀 프레이킹, 로스팅, 익스투르전 및 익스펜딩)의 발전과 더불어, 사료원료의 영양소 이용성이 크게 향상되어 왔다. 분쇄는 입자도의 감소와 함께 가장 널리 사용되는 가공방법이다. 익스펜더는 익스트루더와 유사한 구조이며 짧은 시간으로 고온고압의 과정을 거쳐 생산되어지는 과정이다. 이러한 가공은 펠렛 질을 향상시키기 위해 사용한다. 또한 사료원료의 익스펜딩은 성장 및 영양소 소화율의 향상을 보여준다. 사료 비용은 양돈 생산에 가장 큰 경제적 비중을 차지하기 때문에 영양소 이용률의 극대는 계속적으로 크게 관심이 되어질 것이다. 결국, 이러한 관심은 가축성장과 영양소 소화율에 있어 일률적인 향상을 주게 될 사료가공기술이 계속적으로 되어질 것이다.

• 한국생산제조학회지
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• 제20권5호
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• pp.535-540
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• 2011

It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.

• 한국안전학회지
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• 제20권1호
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• pp.94-100
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• 2005

The plasma, ionized gas state, is generally composed as the 4th state in the universe. Generating the plasma artificially has been studied by spending energy and it has been applied so much in human's life. There are several merits to modify the surface of polymer using plasma. Above all, plasma maintains the properties of polymer itself, but changes the properly of polymer surface only. Also, it is the environmentally fraternized because there are no waste processing from organic solvent. Furthermore, it is possible that continuous automated-processing in case of high-pressure plasma. Therefore, we have tried the reforming of surface to rise the adhesive strength between the material of polymer, and have experimented rising the adhesive strength through peel strength by virtue of processing time and using gas, of course, confirmed the change of polymer surface through measuring the contact angle analysis and scanning electron microscopy(SEM).