• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.399-405
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• 2001

Urushiol, a natural pro-electrophilic quinone compound, has potential structural characteristics as antitumor chemotherapeutic agents. However, urushiol's use as an antitumor drug has some problems, because it is hardly miscible with an aqueous solution. Purified urushiol is highly viscous and soluble only in strong solvents. for this study, we prepared an urushiol-ethanol micro-emulsion with a unimodal size distribution by high-speed homogenization. This generated effective delivery of urushiol to its action wites, so that we could investigate its cytotoxic activity against cancer cells. Using a colony-forming assay, we were able to show that urushiol selectively inhibited the growth of the ovarian cancer cells PA-1 and 2774 at a concentration of $10^{-6}$, whereas it had only a negligible effect on normal CHO cells at the same concentration. The data suggest that urushiol may have potential as an effective antitumor agent in the treatment of ovarian cancer. In addition, we addressed the question of whether the specific cytotoxic effect of urushiol is linked to apoptosis, by DNA fragmentation and DAPI staining assays. The inhibitory effects of urushiol on the growth of ovarian cancer cells was found to be associated with DNA fragmentation and the fragmented nuclei formation, both of which represent markers for the induction of apoptosis. Therefore, the results suggested that urushiol affected its profound cytotoxicity by triggering apoptosis in ovarian cancer cells.

• 한국전자파학회논문지
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• 제13권3호
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• pp.288-300
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• 2002

본 논문에서는 최근 IMT-2000 시스템에서 고속데이타 통신을 수용하기 위해 연구되고 있는 다중입력다중 출력(Multiple Input Multiple Output) 안테나를 이용한 공간분할기법을 현실화하기 위한 새로운 등화된 RF 수신부 구성방법을 제안하였다. 제안된 방법의 핵심은 보정시간 동안 궤환회로 및 기억회로를 통해 보정시간중 등화된 다수의 RF 수신부 구성방법에 있으며, 이를 이용할 경우 중간주파 영역에서 weighting 하는 것이 가능하게된다 이는 기존에 연구된 전파노래 각 알고리듬을 사용 가입자 분포에 따라 안테나 빔 형성하는 것을 가능케 하며, 공간분할에 의한 최적 셀 형성을 가능하게 학 것이다. 또한 제시된 RF 전단부의 동작을 확인하기 위하여 Envelope Simulation을 사용 이의 동작을 검증하였다.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.103-111
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• 2006

The spray behavior of direct-injection spark-ignition(DISI) engines is crucial for obtaining the required mixture distribution for optimal engine combustion. The spray characteristics of DISI engines are affected by many factors such as piston bowl shape, air flow, ambient temperature, injection pressure and fuel temperature. In this study, the effect of fuel temperature on the spray and combustion characteristics was partially investigated for the wall-guided system. The effect of fuel temperature on the fan spray characteristics was investigated in a steady flow rig embodied in a wind tunnel. The shadowgraphy and direct imaging methods were employed to visualize the spray development at different fuel temperatures. The microscopic characteristics of spray were investigated by the particle size measurements using a phase Doppler anemometry(PDA). The effect of injector temperature on the engine combustion characteristics during cold start and warming-up operating conditions was also investigated. Optical single cylinder DISI engine was used for the test, and the successive flame images captured by high speed camera, engine-out emissions and performance data have been analyzed. This could give the way of forming the stable mixture near the spark plug to achieve the stable combustion of DISI engine.

• 콘크리트학회지
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• 제20권6호
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• pp.28-35
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• 2008

700미터 이상의 높이와 160층 이상으로 설계된 버즈두바이가 완공되면 버즈두바이는 인간이 건축한 건축물 중에서 최고높이의 건축물이 될 것이다. 바람의 동적효과를 완화하고 제어시키는 것이 가장 중요한 설계요소중의 하나이며, 설계초기의 공기역학적 형상과 풍공학에 대한 고려가 이러한 주상복합건물의 건축적 형상 및 디자인에 있어 큰 역할을 하는 반면, 건물의 구조시스템을 위한 재료 선택 또한 디자인의 중요한 요소이고 그 다음으로 세부적인 재료기술에 대한 평가 및 기술자 수급이 요구되어진다. 콘크리트는 콘크리트의 강도, 강성, 감쇠, 잉여력, 형틀성, 내화성, 시공성, 원가 등을 고려하여 선정된다. 이 논문은 콘크리트를 활용한 구조시스템을 적용하면서의 설계적으로 도전되었던 부분과 버즈두바이의 콘크리트공사의 초기계획에 대해 집중적으로 다룰 것이다.

• 패션비즈니스
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• 제23권1호
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• pp.37-48
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• 2019

WKSF (Warp-knitted spacer fabrics) knitted using a double Raschel machine is the three-dimensional knit that has vertically connected separate layers in loop structures. Because of its unique structure, the fabric is light, compressible and breathable. Owing to the high production speed, the use of the fabric is increasing in various areas. The purpose of this study is to establish the design process in the utilization of WKSF program and analyze the difference between WKSF and Neoprene as garment materials.. The study on the design related to WKSF has rarely been carried out because of the complexity of WKSF structure and the difficulties encountered in analyzing the structure and thread. Therefore, checking beforehand the simulation results similar to a final knit using the CAD program for WKSF can only enhance the efficiency of the design for the light knits. The conclusion drawn after designing the light knits using the CAD program and analyzing the pros and cons of WKSF through the various property evaluation techniques is as follows. The tension characteristic analysis results indicated that Neoprene specimen has the elastic transformation and resilience, thus behaving like an elastic product such as rubber. By contrast, in the event that clothing and fashion accessories are designed with WKSF, these products are kept in a boxy style fit so that the fabric can be applied flexibly to a curvy body line. In addition, WKSF is good in forming noticeably around a curvy body, because its resistance shear deformation is lower than that of Neoprene.

• 한국분말재료학회지
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• 제29권1호
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• pp.14-21
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• 2022

In the powder bed fusion (PBF) process, a 3D shape is formed by the continuous stacking of very fine powder layers using computer-aided design (CAD) modeling data, following which laser irradiation can be used to fuse the layers forming the desired product. In this method, the main process parameters for manufacturing the desired 3D products are laser power, laser speed, powder form, powder size, laminated thickness, and laser diameter. Stainless steel (STS) 316L exhibits excellent strength at high temperatures, and is also corrosion resistant. Due to this, it is widely used in various additive manufacturing processes, and in the production of corrosion-resistant components with complicated shapes. In this study, rectangular specimens have been manufactured using STS 316L powder via the PBF process. Further, the effect of heat treatment at 800 ℃ on the microstructure and hardness has been investigated.

• Smart Structures and Systems
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• 제32권5호
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• pp.281-295
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• 2023

The purpose of this study is to demonstrate and verify the application of phase-control absolute-acceleration-feedback active tuned mass dampers (PCA-ATMD) to multiple-degree-of-freedom (MDOF) building structures. In addition, servo speed control technique has been developed as a replacement for force control in order to mitigate the negative effects caused by friction and inertia. The essence of the proposed PCA-ATMD is to achieve a 90° phase lag for a structure by implementing the desired control force so that the PCA-ATMD can receive the maximum power flow with which to effectively mitigate the structural vibration. An MDOF building structure with a PCA-ATMD and a real-time filter forming a complete system is modeled using a state-space representation and is presented in detail. The feedback measurement for the phase control algorithm of the MDOF structure is compact, with only the absolute acceleration of one structural floor and ATMD's velocity relative to the structure required. A discrete-time direct output-feedback optimization method is introduced to the PCA-ATMD to ensure that the control system is optimized and stable. Numerical simulation and shaking table experiments are conducted on a three-story steel shear building structure to verify the performance of the PCA-ATMD. The results indicate that the absolute acceleration of the structure is well suppressed whether considering peak or root-mean-square responses. The experiment also demonstrates that the control of the PCA-ATMD can be decentralized, so that it is convenient to apply and maintain to real high-rise building structures.

• 보존과학회지
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• 제26권2호
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• pp.149-156
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• 2010

금속 유물 코팅제로 사용되는 V-Flon은 함께 사용되는 용제인 YK-D80의 늦은 휘발성으로 작업에는 용이하나, 후처리로 유물을 접합하거나 복원처리 시, 코팅제가 완전 경화되지 않고 흘러나오는 문제점이 발생한다. 따라서 함침처리 후에 코팅제의 경화 속도를 가속시키기 위해 열풍 건조기에서 경화시키는 경우가 대부분이다. 이러한 V-Flon의 용제 휘발 속도의 문제점을 보완하고자 적용시키는 열풍 건조에 대한 문제점을 알아보고, 용제와 농도에 따른 변화 정도를 살펴보아 가장 효과적인 용제와 그 조성을 찾고자 하였다. 6 종류의 용제를 선정하였고 농도는 10%, 20%, 30%의 세 가지 농도로 함침 처리하여 시편을 제작하였다. 그리고 시편의 상태를 알아보기 위해서 금속 표면의 색상 및 광택 변화, 코팅막 두께 측정, 코팅 후의 부식 실험, 접촉각을 통한 내수성 측정을 실시하여 코팅제의 안정성을 평가하였다. 자연 건조와 열풍 건조의 비교 실험 결과, 열풍 건조는 외부의 강제 건조로 데이터 값이 불안정하여 균일하고 안정한 코팅막 형성에는 문제가 있음을 확인할 수 있었으며, 용제의 농도에 따른 실험 결과 V-Flon을 Xylene 용제를 이용하여 10% 용액으로 제조하여 사용할 경우, 얇은 코팅막에도 불구하고 높은 수분 차단성을 가지고 있었으며, 낮은 광택과 색변화를 나타내는 안정된 코팅막을 형성할 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권6호
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• pp.807-815
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• 2015

The present study aimed at evaluating the intensity of Tifton 85 conditioning using a mower conditioner with free-swinging flail fingers and storage times on dehydration curve, fungi presence, nutritional value and in vitro digestibility of Tifton 85 bermudagrass hay dry matter (DM). The dehydration curve was determined in the whole plant for ten times until the baling. The zero time corresponded to the plant before cutting, which occurred at 11:00 and the other collections were carried out at 8:00, 10:00, 14:00, and 16:00. The experimental design was randomised blocks with two intensities of conditioning (high and low) and ten sampling times, with five replications. The high and low intensities related to adjusting the deflector plate of the free iron fingers (8 and 18 cm). In order to determine gas exchanges during Tifton 85 bermudagrass dehydration, there were evaluations of mature leaves, which were placed in the upper middle third of each branch before the cutting, at every hour for 4 hours. A portable gas analyser was used by an infrared IRGA (6400xt). The analysed variables were photosynthesis (A), stomatal conductance (gs), internal $CO_2$ concentration (Ci), transpiration (T), water use efficiency (WUE), and intrinsic water use efficiency (WUEi). In the second part of this study, the nutritional value of Tifton 85 hay was evaluated, so randomised blocks were designed in a split plot through time, with two treatments placed in the following plots: high and low intensity of cutting and five different time points as subplots: cutting (additional treatment), baling and after 30, 60, and 90 days of storage. Subsequently, fungi that were in green plants as well as hay were determined and samples were collected from the grass at the cutting period, during baling, and after 30, 60, and 90 days of storage. It was observed that Tifton 85 bermudagrass dehydration occurred within 49 hours, so this was considered the best time for drying hay. Gas exchanges were more intense before cutting, although after cutting they decreased until ceasing within 4 hours. The lowest values of acid detergent insoluble nitrogen were obtained with low conditioning intensity after 30 days of storage, 64.8 g/kg DM. The in vitro dry matter of Tifton 85 bermudagrass did not differ among the storage times or the conditioning intensities. There was no fungi present in the samples collected during the storage period up to 90 days after dehydration, with less than 30 colony forming units found on plate counting. The use of mower conditioners in different intensities of injury did not speed up the dehydration time of Tifton 85.

• 한국터널지하공간학회 논문집
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• 제24권5호
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• pp.395-409
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• 2022

기존 암반 굴착공법이 갖는 한계점을 극복하기 위해 최근 연마재 워터젯 공법을 활용하는 연구가 활발히 진행되고 있다. 연마재 워터젯 암반굴착 공법은 암반에 연속적인 자유면을 형성하여 발파 시 발생하는 진동을 저감하고 굴착효율을 증진시키는 효과가 있다. 그러나 연마재 워터젯 절삭성능은 암반의 물리적 성질에 따라 변화한다. 따라서, 다양한 물리적 성질을 가진 암반이 혼재하는 굴착현장 특성상 효과적인 워터젯 활용을 위해서는 다양한 암종의 절삭성능을 분석하는 것이 필수적이다. 본 연구에서는 현무암과 화강암을 대상으로 수압, 이격거리, 이송속도를 변화시키며 절삭실험을 수행하고 결과를 분석하였다. 실험결과, 현무암은 화강암보다 평균적으로 약 41% 깊게 절삭되고, 절삭 폭은 약 18.5% 좁게 형성되었다. 본 연구결과는 향후 현무암과 같은 강도가 낮고 공극이 큰 암반 굴착현장에서 연마재 워터젯을 적용할 시 유용한 기초자료로 활용될 것으로 기대된다.