• 소성∙가공
• /
• 제18권2호
• /
• pp.166-171
• /
• 2009

In this paper, a basic study on micro cutting process with SM20C at low temperature environment was performed. In macro cutting fields, the cryogenic cutting process has been applied to cut the refractory metal but, the serious problem may be generated in micro cutting fields by the cryogenic environment. However, if the proper low temperature is applied to micro cutting area, the cooling effect of cutting heat is expected. Such effect can make the reduction of tool wear and burr formation. For verifying this possibility, the micro cutting experiment at low temperature was performed and SEM images were analyzed.

• Applied Microscopy
• /
• 제14권2호
• /
• pp.38-51
• /
• 1984

Fine structure of dormant and swollen conidiospore from Trichoderma koningii and the mechanism of protoplasting from the conidiospore were studied by scanning and transmission electron microscopy. The cell wall of dormant conidiospore was two-layered structure which consisted of electron dense outer layer and electron transparent inner layer. After 8.5 hrs incubation. the conidiospore was swollen and the outer layer of cell wall shown unequal thickness and partial breakage. Protoplast was released through the pore which has been formed by the breakage of outer layer and dissolution of newly synthesized cell wall for germ-tube formation. Swollen conidiospore and protoplast in releasing process contained various cell organelles and vacuoles with electron dense materials. The protoplast contained looser cytoplasm and had no cell wall materials outside of plasmamembrane.

• 한국산업융합학회 논문집
• /
• 제1권2호
• /
• pp.49-54
• /
• 1998

In the catalytic combustor, combustion characteristic and deterioration of catalysts were affected by non-uniformity of pre-mixed gas, Therefore, formation of uniform pre-mixed gas is one of important subjects. In this study, the effect of uniformity and non-uniformity of pre-mixed gas supplied to the catalyst was examined to clarify reaction acceleration and combustion characteristic of the catalytic combustion. It was clarified that static mixer or vaporizer tube length of about 150mm and weak swirl to a combustion air were effictive expedient to make uniform pre-mixed gas. And catalystic inlet temperature needs more than $600^{\circ}C$ with rich pre-mixed gas to active reaction.

• Journal of Microbiology and Biotechnology
• /
• 제5권1호
• /
• pp.41-47
• /
• 1995

Biodegradation of toluene in liquid effluent stream was carried out using biofilms of Pseudomonas putida formed on celite particles in the bubble column bioreactor. Silicon rubber tubing was installed at the bottom of the bioreactor and liquid toluene was circulated within the tubing. Toluene diffused out of the tube wall and was transferred into the culture broth where degradation by biofilms occurred. The operating variables affecting the formation of biofihns on celite particles were investigated in the bubble column bioreactor, and it was found that formation of bifilm is favored by high dilution rate and supply rate of carbon source which stimulate the growth of initially attached cells. Continuous biodegradation of toluene using biofilms was stablely conducted in the bioreactor for more than one month without any significant fluctuation, showing a removal efficiency higher than 95% at the toluene transfer rate of 1.2 g/L/h.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
• /
• pp.202-202
• /
• 2011

Thermal energy storage(TES) cooling system using cheaper electricity of off-peak time has been applied to relief a significant portion of the peak demand of electricity during the daytime in summer. Slurry ice type thermal energy storage cooling system is one kind of more efficient ice-thermal energy storage cooling system than Ice-on-Coil type or Encapsulated type TES cooling system, even though, which are more popular TES system. This study is experimented to observe flow pattern and formation of slurry ice in reversing flow to improve efficiency of heat transfer between fluid and freezing tube.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
• /
• pp.43-46
• /
• 2012

The oxygen concentration of primary oxidizer is decided under 10% due to flammable risk. It can be a spontaneous combustion inside burner or tube if the excess oxygen is added to primary oxidizer in Oxy-PC burner. In this case, the rest oxygen which can not be injected to primary oxidizer should be injected to another port. If added it to a second oxidizer, the ignition is unstable at outlet of burner. Accordingly an extra lancing port is needed to insert into the burner unlike other common air mode. And the flame formation and combustion characteristic differ from lancing port position. Therefore we observed flame formation which has stable combustion characteristic according to the shape and position of lancing port.

• 동의생리병리학회지
• /
• 제19권5호
• /
• pp.1363-1369
• /
• 2005

Previously we have shown that shikonin has strong anti-tumor activities via inducing apoptosis and suppressing metastasis on LLC cells in vivo and in vitro. Here we have investigated anti-angiogenic potential of shikonin and its possible mechanism of action in HSE cells. Shikonin inhibited the proliferation of HSE cells in a concentration-dependent manner. It was shown that this proliferation inhibition was caused by apoptosis induced by shikonin via BrdU incorporation and Western blotting analysis. Shikonin treatment was caused that decrease of activation of caspases and cleavage of PARP. And shikonin induced that the activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38. Moreover, shikonin showed anti-angiogenic activities inhibiting tube-like formation of HSE cells in vitro and vascular formation of LLC cells in vivo. These findings suggest that shikonin may a possible candidate not only anti-metastatic agent but also anti-angiogenic agent.

• 약학회지
• /
• 제43권6호
• /
• pp.771-775
• /
• 1999

The antimutagenic activities of the total extract and several fractions of starfish, Asterina pectinifera (Asteriidae), were investigated in vitro by SOS chromotest with Escherichia coli PQ37 and Ames test with Salmonella typhimurium TA100. When various fractions was tested, the chloroform and butanol fractions showed low induction factors, which means both fractions increased antigenotoxicity against the base substitution mutagen MNNG. Even though higher antigenotoxic effect of the chloroform fraction, no effective result of Ames test was found in revertant formation of S. typhimurium TA100. The most effective antigenotoxic and antimutagenic fraction was a butanol one: i.e., When 0.5 mg/tube of butanol fraction was applied, the induction factor was 0.68. As the concentration of the fraction was increased the formation of revertants of S. typhimurium TA100 by about 81%. There was no cytotoxic effect of butanol fraction against S.typhimurium TA100. This result might be useful for further study to search a possible anticancer agent from the starfish, Asterina pectinifera.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.56-57
• /
• 2006

Porosity in spray-formed materials is an important issue, but the formation of porosity is not completely understood. The paper gives some examples picked from literature, which show some general correlations between process parameters and porosity. To improve the understanding of porosity formation it is necessary to know more about the conditions of the droplets and the deposit at the point of impingement. Determining the impact conditions is a challenge because usually they are not constant with time and some values are difficult to measure. Our experiments show a strong correlation between the deposit surface temperature and the porosity. The average impact angle weighted by the local particle mass flux is also an important parameter.

• 한국지반신소재학회논문집
• /
• 제13권2호
• /
• pp.1-10
• /
• 2014

본 연구에서는 준설토 주입 후 튜브 내부 준설토의 퇴적분포가 튜브 형상에 미치는 영향을 분석하기 위해 준설토 주입실험 결과를 바탕으로 튜브 내 준설토의 퇴적분포와 튜브 거동에 대해 소개하였다. 튜브 내 준설토의 퇴적분포를 관찰하기 위해 투명 비닐소재를 사용하여 튜브를 제작하였고, 이때 튜브의 직경(D)은 0.5m와 0.7m이고 길이(L)는 모두 4.0m이다. 주입형태에 따른 튜브 내 준설토의 퇴적분포 형태를 관찰하기 위해 준설토 주입형태는 I-Type과 T-Type을 적용하였다. 실험은 주입, 침강 및 퇴적 후에 준설토 상부의 물을 배수과정에서 제거하고 슬러리 상태의 시료를 재주입하는 과정을 반복하여 수행하였고, 주입 및 배수 단계에서 튜브 내 준설토의 퇴적분포와 튜브의 연직 및 수평 거동을 관찰하였다. 주입실험 결과 I-Type 주입의 경우 크레이터 형성에 의한 부유 및 확산퇴적이 동시에 발생되는 분리퇴적에 의해 비균질 거동을 나타내고, T-Type 주입은 확산수평퇴적으로 인하여 퇴적 튜브 내 준설토가 균등하게 분포하는 것으로 나타났으며, 비배수 초기 연직충진비($H/D_0$)는 0.54~0.64 정도이고 수평변형비($W/D_0$)는 1.45~1.54로 퇴적고는 준설토 충진에 비례하여 증가하나 수평변형비는 일정하거나 감소하면서 튜브체의 중심은 상향이동 되고 있다.