• Journal of Plant Biotechnology
• /
• 제30권1호
• /
• pp.41-45
• /
• 2003

Iris 속 식물인 꽃창포의 번식 특성에서 종자의 잡종성과 적은 분얼로 인한 분주 번식의 어려움을 해결하고 고유한 품종의 특성을 유지하기 위해서는 조직배양을 통한 대량 번식의 구명이 필요하므로 Iris 속 식물의 화기부위 별 절편체를 이용하여 기내 번식에 의한 대량 증식방법을 정립하고자 본 실험을 수행하였다. 자생꽃창포의 화피기부조직, 자방, 소화경, 화경을 치상하여 기내배양환경에 적절한 환경을 구명하고자 조도 2000 Lux에서 일장 (0~24시간), 온도 (10~3$0^{\circ}C$), sucrose (l~9%)의 조건에서 배양하였다. 자생꽃창포의 화기 절편체로부터 유식물체 재분화에 적합한 일장은 16시간의 장일조건이, 온도 조건은 $25^{\circ}C$에서, sucrose 농도는 3%에서 가장 적합한 것으로 나타났으며 특히 화기 부위 중 화피기부조직과 자방 배양에서 높은 신초 형성을 보였다. 화기조직 치상절편체로부터 부정근의 분화는 암상태에서 촉진되어지고 sucrose는 6%에서 뿌리를 생장시키며 1$0^{\circ}C$, 15$^{\circ}C$의 저온에서는 신초,뿌리의 분화가 저조하였다.

• 미생물학회지
• /
• 제6권4호
• /
• pp.113-121
• /
• 1968

This study has been aimed to determine the ecological factors with relationship to the Jongkok production in view of fermentation technology by means of some strains, Asp. kawachii, which is now preserved by the author and the following factors are included during the study; inorganic salts, nitrogen, sugar, water contents and temperature. The results, are as follows: (a) Sugar among other above-mentioned factors is increasingly affecting the number of the short type of conidiophore on culture medium and the conidiophore is increased by direct ratio until glucose concentration of 50%, at which concentration is mostly effective for the short type of conidiophore, while other factors did not affect on it. (b) Until glucose concentration of 50% sugar component of culture medium is favorable for the spore formation of Asp. kawachii by direct ratio. And peptone or asparagine on nitrogen medium, calcium-phosphate among other inorganic salts, wheat bran and rice branare also favorable, but other factors rientioned earlier show no relationship with the spore formation. Sugar, however, also related with the spore color clearness of crimson and light brown, and spore color is mostly clear at the point of glucose concentration until 50%. And asparagine on nitrogen medium, calcium phosphate among other inorganic salts, rice bran did all affect on the color clearness, while other factors did not concern with color clearness. (c) Water, sugar and temperature have related with the acid formation which is promoted, by direct ratio at the point of water-saturated condition and glucose concentration of 50%, while temperature at $25^{\circ}C$favorably affected on the acid formation which is increased by inverse ratio at the temperature$25^{\circ}C$ to $45^{\circ}C$ And pH did not relate with the acid formation. (d) Cylindrical plate method devised by the author is mostly favorable for the preservation and isolation of culture, compared with the traditional slant medium method.

• 한국자동차공학회논문집
• /
• 제14권3호
• /
• pp.1-9
• /
• 2006

Recently, there has been an interest in premixed diesel engines as it has the potential of achieving a more homogeneous and leaner mixture close to TDC compared to conventional diesel engines. Because this concept reduced NOx and smoke emissions simultaneously. Early studies are shown that in a HCCI(Homogeneous Charge Compression Ignition) engine, the fuel injection timing and intake air temperature affect the mixture formation. The purpose of this study is to investigate characteristics of combustion and mixture formation according to injection timing and intake air temperature in a common rail direct injection type HCCI engine using an early injection method called the PCCI(Premixed Charge Compression Ignition). From this study, we found that the fuel injection timing and intake air temperature affect the mixture formation and in turn affects combustion in the PCCI engine.

• 한국재료학회지
• /
• 제18권11호
• /
• pp.604-609
• /
• 2008

The sintering behavior of zircon with silica was investigated. Zircon with 5 vol% of sedimentation $SiO_2$ resulted in the apparent density of $4.45\;g/cm^3$, the diametral tensile strength of $12.125\;kgf/cm^2$, and the micro Vickers hardness of 1283 HV. The dissociation temperature and mechanical characteristics of the $ZrSiO_4$ were changed with different kinds of $SiO_2$. $SiO_2$ addition prevented dissociation of $ZrSiO_4$. Zircon with 5 vol% of sedimentation $SiO_2$ and with 5 vol% of fused $SiO_2$ resulted in increased diametral tensile strength and increased micro Vickers hardness by suppression of $ZrSiO_4$ dissociation and low temperature liquid $SiO_2$ formation. Zircon with fumed $SiO_2$ and quartz $SiO_2$ resulted in decreased diametral tensile strength and decreased micro Vickers hardness because of cristobalite and quartz phase formation and high temperature liquid $SiO_2$ formation. Zircon with 10 vol% of $SiO_2$ resulted in decreased diametral tensile strength and decreased micro Vickers hardness because of weak particle coupling due to excess formation of liquid $SiO_2$.

• 한국자동차공학회논문집
• /
• 제9권3호
• /
• pp.42-50
• /
• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권7호
• /
• pp.889-898
• /
• 2003

The soot yield is studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effect of turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degree intervals in order to observe the soot formation under high pressures and high temperatures. The eight flames converged compress the end gases to a high pressure. The laser schlieren and direct flame photographs for observation field with 10 mm in diameter are taken to examine into the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. It is found that the soot yield of turbulent combustion decreases in comparison with that of laminar combustion because the burnt gas temperature increases with the drop of heat loss.

• 대한기계학회논문집
• /
• 제18권10호
• /
• pp.2712-2723
• /
• 1994

Numerical simulation of an axisymmetric ethylene-air jet diffusion flame has been carried out in order to investigate flame dynamics and soot formation. The model solves the time-dependent Navier-Stokes equations and includes models for soot formation, chemical reaction, molecular diffusion, thermal conduction, and radiation. Numerically FCT(Flux Corrected Transport) and DOM(Discrete Ordinate Method) methos are used for convection and radiation trasport respectively. Simulation was conducted for a 5 cm/sec fuel jet flowing into a coflowing air stream. The maximum flame temperature was found to be approximately 2100 K, and was located at an axial position of approximately 5 cm from the base of the flame. The maximum soot volume fraction was about $7{\times}10^{-7}$, and was located within the high temperature region where the fuel mole fraction ranges from 0.01 to 0.1. The buoyancy-driven low-frequency(12~13 Hz) structures convected along the outer region of the flame were captured. In case without radiation trasport, the maximum temperature was higher by 150 K than in case with radiation. Also the maximum soot volume fraction reached about $8{\times}10^{-6}$. As the the hydrocarbon fuel forms many soot particles, the radiation transport becomes to play a more important role.

• 설비공학논문집
• /
• 제21권11호
• /
• pp.643-648
• /
• 2009

Tests were conducted to obtain heat transfer coefficients during slush formation from 10% sucrose solution. The slush was made by scraping the ice formed on the cylinder. Cold brine was supplied inside of the evaporator cylinder to cool the outer surface. Below a certain brine temperature, which was $-5^{\circ}C$ in this study, the solution was supercooled, and suddenly turned into ice crystals. During slush formation, the heat transfer coefficient oscillated significantly, due to periodic removal of ice chunk form the surface. The average heat transfer coefficient during slush formation was 40~70% higher than that obtained during single phase cooling. The heat transfer coefficient was also affected by the brine temperature with increasing heat transfer coefficient at higher brine temperature.

• 한국균학회지
• /
• 제17권4호
• /
• pp.194-196
• /
• 1989

Ganoderma lucidum의 비자실체성(非子實體性) 담자포자(擔子胞子)의 형성(形成)에 미치는 온도(溫度) 및 환기(換氣)의 영향(影響)을 조사(調査)하였다. 비자실체성(非子實體性) 담자포자(擔子胞子)는 $30^{\circ}C$에서 가장 잘 형성(形成)되었고 $15^{\circ}C$ 및 $35^{\circ}C$에서는 형성되지 않았다. 포자(胞子)의 형성(形成)에 있어서는 환기(換氣) 조건(條件)이 필요(必要)하였고 포화(飽和) 습도하(濕度下)에서는 포자(胞子)가 형성(形成)되지 않았다.

• Journal of Welding and Joining
• /
• 제31권6호
• /
• pp.8-16
• /
• 2013

As the energy consumption increases rapidly, power generation needs the high energy efficiency continuously. To achieve the high efficiency of power generation, the materials used have to endure the higher temperature and pressure. The 9-12%Cr steels possess good mechanical properties, corrosion resistance, and creep strength in high temperature due to high Cr contents. Therefore, the 9-12%Cr steels are widely used for the high-temperature components in power plants. Even though the steels usually have a fully martensitic microstructure, they are susceptible to the formation of ${\delta}$-ferrite specifically during the welding process. The formation of ${\delta}$-ferrite has several detrimental effects on creep, ductility and toughness. Therefore, it is necessary to avoid its formation. As the volume fraction of ${\delta}$-ferrite is less than 2% in microstructure, it has the isolated island morphology and causes no significant degradation on mechanical properties. For ${\delta}$-ferrite above 2%, it has a polygonal shape affecting the detrimental influence on the mechanical properties. The formation of ${\delta}$-ferrite is affected by two factors: a chemical composition and a welding heat input. The most effective ways to get a fully martensite microstructure are to reduce the chromium equivalent less than 13.5, to keep the difference between the chromium and nickel equivalent less than 8, and to reduce the welding heat input.