• Journal of Ginseng Research
• /
• 제6권1호
• /
• pp.11-16
• /
• 1982

New shoot growth of Panax ginseng root was investigated comparing with burley and soybean from l0$^{\circ}C$ to 30$^{\circ}C$ under dark. Shoot growth ceased by 12days at 30$^{\circ}C$ and optimum temperature appeared to be 15$^{\circ}C$/20$^{\circ}C$ (15hrs/9 hrs) , and 15$^{\circ}C$/15$^{\circ}C$ for ginseng. Shoot growth seems to be Poor below l0$^{\circ}C$. Temperature for maximum growth 20$^{\circ}C$/20$^{\circ}C$ for barley and 20$^{\circ}C$ /25$^{\circ}C$ for soybean. Barley did not germinate above 25$^{\circ}C$/25$^{\circ}C$, but grow better than soybean below 15$^{\circ}C$/25$^{\circ}C$. Fresh weight of 2 weeks suggesting cessation of water uptake at higher temporal use. Ginseng showed greater root ply s shoot of ginseng was linearly increased at 15$^{\circ}C$ but did not increased at 25$^{\circ}C$ after occurence of die-back of new shoot or root rot above 25$^{\circ}C$.

• 소성∙가공
• /
• 제13권1호
• /
• pp.84-89
• /
• 2004

There is a growing interest to replace the commercial steels with non-heat treated steels, which does not involve the spheroidization and quenching-tempering treatment. However, Non-heat treated steels should satisfy high strength and good formability without performing heat treatment. Therefore, it is important to investigate optimum materials showing a good combination of strength and formability after the drawing process. In this study, Dual-Phase Steels were studied as candidate materials for non-heat treated steels, which have different martensite morphologies and volume fractions obtained through heat-treatment of intercritical quenching (IcQ), intermediate quenching (ImQ) and step quenching (SQ). The mechanical properties of DP steels were measured by tension and compression tests. Also, the cold formability of three DP steels which have similar tensile strength value was investigated by estimating the deformation resistance and the forming limit. The deformation resistance which is important factor in determining die life was estimated by calculating the deformation energy. And the forming limit was estimated by measuring the critical strain revealing crack initiation at the notch tip of the specimens.

• 한국생산제조학회지
• /
• 제20권6호
• /
• pp.824-829
• /
• 2011

The mold is widely used for mass production in present industry. Also, product cycle time is faster, for this request, high productivity improvement in mold machining is required. And, In case of mold manufacturing company, the delivery shortening is required to quickly manufacture new product. Therefore, we aim for the delivery shortening though the method of machining time shortening in mold machining. On this paper, first, we made the NC-code of Insert die-casting as the object model using PowerMill. And then, analyzed cutting force by Toolpath in Insert mold machining using Production Module of Advantedge which is cutting force analysis program. After that, we came up with the optimum conditions of productivity improvement throughout the analysis result of before and after optimization of cutting force, machining time variation, and surface roughness by changing min tangential force to 80, 85, 90% of max tangential force.

• Korea-Australia Rheology Journal
• /
• 제20권4호
• /
• pp.235-243
• /
• 2008

The aim of this study is to explore the possibility of incorporating supercritical carbon dioxide ($scCO_2$) into twin screw extrusion process for the production of polypropylene-clay nanocomposite (PPCN). The $CO_2$ is used as a reversible plasticizer which is expected to rapidly transport polymeric chains into the galleries of clay layers in its supercritical condition inside the extruder barrel and to expand the gallery spacings in its sub-critical state upon emerging from die. The structure and properties of the resulting PPCNs are characterized using wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), rheometry, thermogravimetry and mechanical testing. In the processing of the PPCNs with $scCO_2$, optimum $scCO_2$ concentration and screw speed which maximized the degree of intercalation of clay layers were observed. The WAXD result reveals that the PP/PP-g-MA/clay system treated with $scCO_2$ has more exfoliated structure than that without $scCO_2$ treatment, which is supported by TEM result. $scCO_2$ processing enhanced the thermal stability of PPCN hybrids. From the measurement of linear viscoelastic property, a solid-like behavior at low frequency was observed for the PPCNs with high concentration of PP-g-MA. The use of $scCO_2$ generally increased Young's modulus and tensile strength of PPCN hybrids.

• 품질경영학회지
• /
• 제44권4호
• /
• pp.935-949
• /
• 2016

Purpose: This study attempts to find out the optimum condition of the rotary cutter making pellet in the footwear outsole process. The pellets are used in the process of outsole rubber fabrication to reduce cycle time and save raw material. Methods: Computer simulations are used to analyze the maximum stress in the rotary cutter after designing a variety of cutter shapes. Taguchi method is used to identify the robust condition of the cutter. In $L_{18}$ orthogonal array, the control factors such as knife width, twisted angle, number of knives, diameter, knife depth and supported angle are considered and noise factors like assembly tolerance and amount of antifriction are allocated. Results: It is found that the most important factors to reduce maximum stress in the cutter are supported angle and diameter. Using Tacuchi's results, we can reduce 70% cycle time and 9% raw material compared to the traditional method using cutting die. Conclusion: When designing the rotary cutter, the best conditions are the diameter at its maximum allowable value and supported angle in the boundary of machine inner space.

• 한국분말재료학회지
• /
• 제13권2호
• /
• pp.124-128
• /
• 2006

In recent years, equal channel angular pressing (ECAP) has been the subject of intensive study due to its capability of producing fully dense samples having a ultrafine grain size. In this paper, the ECAP process was applied to metallic powders in order to achieve both powder consolidation and grain refinement. In the ECAP process for solid and powder metals, knowledge of the internal stress, strain and strain rate distribution is fundamental to the determination of the optimum process conditions for a given material. The properties of the ECAP processed solid and powder materials are strongly dependent on the shear plastic deformation behavior during ECAP, which is controlled mainly by die geometry, material properties, and process conditions. In this study, we investigated the consolidation, plastic deformation and microstructure evolution behaviour of the powder compact during ECAP.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 제3회 금형가공 심포지엄
• /
• pp.260-265
• /
• 2004

LTCC(Low temperature co-fired ceramic) is being recognized as a significant packaging material of electrical devices for the advantages such as relatively low temperature being needed for process, low conductor resistance and high printing resolution. In the process of LTCC electrical devices, the punched via-hole quality is one of the most important factors on the performance of the device. However, its mechanism is very complicated and optimization of the process seems difficult. In this paper, to clarify the process, via-hole punching experiments were carried out and the punched holes were examined in terms of their burr formation. The effects of thickness of PET sheet and ceramic sheet and punch-to-die clearance on via-hole quality were also discussed. Optimum process conditions are proposed and a factor k is introduced to express effect of the process variables.

• Elastomers and Composites
• /
• 제55권3호
• /
• pp.184-190
• /
• 2020

In the wet master batch process, process oil is used to improve the workability of silica-SBR. The process oil expands the polymer and provides lubrication to soften the stiff rubber chain. However, addition of excess process oil can interfere in the crosslinking reaction between rubber molecules and reduce the crosslinking density of silica-SBR. Controlling the amount of process oil is an important aspect for properly controlling the workability and crosslinking density of silica-SBR. In this study, silica-SBR was prepared by adjusting the amount of process oil to confirm its effect on silicaSBR. Vulcanization characteristics of silica-SBR were examined using a moving die rheometer. Dynamic viscoelasticity was measured using a dynamic mechanical thermal analyzer, and the mechanical properties were investigated using the universal testing machine according to ASTM D412. As a result, all silica-SBR compounds with 10 to 40 phr of process oil have effects of improving the processability and the silica dispersibility. Also, the optimum condition was determined when 10 phr of processed oil was added because the abrasion resistance was improved 65% compared to that at 40 phr.

• 한국레이저가공학회지
• /
• 제18권2호
• /
• pp.1-4
• /
• 2015

This study is related to the surface hardening treatment to spheroidal graphite cast iron for die by using high power diode laser. Laser device used in this experiment is capable of real-time laser power control. This is because the infrared temperature sensor (two color pyrometer) attached to the optical system measures the surface temperature of specimen and adjusts the laser power in real time. The surface treatment was carried out with the change of heat treatment temperature at the beam travel speed 3 mm/sec. Hardened width and depth was measured and hardened zone was analyzed by micro vickers hardness test in order to research the optimum condition of heat treatment. The changes in microstructure of the hardened zone also was examined. As a result of hardness measurement and observations on microstructure of hardened zone, hardness increased over three times as compared with base metal because the martensite was formed on the matrix structure.

• 아시안잔디학회지
• /
• 제7권1호
• /
• pp.31-34
• /
• 1993

There is a growing concern in the United Stares over the environmental and human health implications associated with heavy use of water, pesticides, and inorganic ferilizers in maintaining picture perfect golf courses. There is also a growing awareness that a beautiful course is not necessarily a healthy course. The following discussion reviews the interrelationship of turfgrass and the soil that supports it and provides basic information on currently available alternatives to turf management practices that feature intensive application of inorganic fertilizers. water and pesticides. Soil is a dynamic natural environment in which microorganisms play an important role. Soil contains a large mass of microorganisms which produce thousands of enzymes that can catalyze the transformation and degradation of many organic molecules. (In top soil under optimum conditions may contain 10 billion cells per gram of soil.). Turfgrass and the soil which supports it are interdependent. The natural organic cycle as applied to turf and soil begins with healthy vigorous grass plants storing up the sun's energy in green plant tissues as chemical energy. Animals obtain energy by eating plants and when plants and animals die, their wastes are returned to the soil and provide "food" for soil microorganisms. In the next step of the organic cycle soil microorganisms break down complex plant tissues into more basic forms and make the nutrients available to grass roots. Finally, growing plants extract the available nutrients from the soil. By free operation of this organic cycle, natural grasslands have some of the most fertile soils on earths.