• Korean Journal of Environment and Ecology
• /
• v.20 no.4
• /
• pp.436-447
• /
• 2006

Recently, there is increasing demand on enhancing the efficiency of hydro-seed spraying in afforestation for damaged or degraded land including forest road slopes. In this study, we focus on how seed coating and molding may affect seed germination and seedling growth. Plant species used in the study are Lespedeza cyrtobotrya, Indigofera pseudotinctoria, Arudineila hirta, Poa pratensis, and Lolium perenne. The results of seed germination and seedling growth with and without seed coating and molding are analyzed as follows: 1. For all the species and in both seeding with molding covered with soil and seeding without molding in which seeds were over sown, the increment of germination ratio by seed coating method is greater than by non·coating one. Seed coating increases average germination ratios observed in seeding with molding and without molding by 11.2% and 21.4%, respectively. Germination force may decrease from 0.8 to 3.7 days depending on the plant species and the treatments. The $LD_{50}$ decreased by $0.8{\sim}2.6$ days. However, seed coating delays the start of germination by approximate 1 day for all of the observed plants. 2. Seed coating may have the effect of accelerating the growth of stem and leaf and root. The experimental result shows that seed coating leads to 21.7% and 34.8% increment of average stem and leaf growth by seeding with molding and without molding, respectively. In terms of root growth, seeding with molding results in 22.0% increment while seeding without molding produces 26.2% increased root growth. 3: Compared to seeding without molding, germination starts on an average of 1.3 days later in seeding coated seeds with molding. However. the germination ratio is increased by 5%, and germination force and $LD_{50}$ are observed to shorten by 1.0 day and 1.4 days, respectively. Meanwhile, whether seeds are coated or not may be more related with germination and seedling growth in seeding without molding than with those in seeding with molding. 4. In this study, coating materials are examined to look at which ones are better in each treatment. Coating with Vermiculite+Talcum is the most effective in germination and seedling growth for overall plants. Seed coating using Bentonite, Calcium Carbonate, and Calcium Hydroxide shows better results than non-coating does. 5. When seeds are coated, the greatest enhancement of seed germinations was observed in Indigofera pseudotinctoria and, in the case of seedling growth, Lespedeza cyrtobotrya has the most increasing observation value among the 5 examined species. These results may indicate that woody plant seeds, having greater sizes of seeds than ones of grass seeds, may have greater relation with seed coating than grass plant seeds may have. 6. Therefore, if seeds cannot be molded up after hydro-seeding on forest road slopes, it is recommended that seeds for restoration be pre-coated with Vermiculite+Talcum and then be sowed, in order to quickly stabilize the damaged slope and achieve successful afforestation.

• Transactions of Materials Processing
• /
• v.29 no.5
• /
• pp.251-256
• /
• 2020

The purpose of this study is to investigate the effect of sintering condition on the microstructure evolution and tensile properties of the Ti-6Al-4V alloy sample processed by metal injection molding (MIM) in terms of the sizes of the alpha morphology and pore found in the matrix. For this purpose, a series of MIM were conducted on this sample at various sintering temperatures ranging from 1173 to 1373 K for three hours followed by furnace cooling, observed by the scanning electron microscopy. The microstructures sintered in this study showed that, with increasing sintering temperature over beta transus temperature, the transformation of the equiaxed alpha into transformed beta was attained while the size of pores would tend to decrease. Thus, the strength remained unchanged significantly in the tension while ductility increased to some extent as sintering temperature increased. Such mechanical behavior would be explained in relation to the microstructure evolution of the Ti-6Al-4V sample via the MIM.

• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.26-30
• /
• 2005

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result, the stamper surface temperature was controlled according to the desired reference stamper surface temperature.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.2
• /
• pp.100-104
• /
• 2006

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result. the stamper surface temperature was controlled according to the desired reference stamper surface temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.5
• /
• pp.353-357
• /
• 1998

Cracking problem of Epoxy Molding Compound(EMC) is critical for the reliability of the plastic package during temperature cycling and IR-reflow condition. Fracture toughness of EMC, which is defined as the resistance of EMC to the crack propagation, is a useful factor in ht estimation of EMC against package crack. Thus, development of EMC having high fracture toughness at a given loading condition would be important for confirming the integrity of package. In this study, toughness of several EMC was measured by varying the test conditions such as temperature, loading speeds, and weight percent of filler in order to quantify the variation of toughness of EMC under various applicable conditions. It was found from the experiments that toughness of all EMC has following trends, i.e., it rapidly decreases over the glass transition temperature, remains almost same or little decreases below $0^{\circ}C$. It decreases with the growth of cross head speed in EMC and the weight percent of filler as the degree of brittleness of EMC increases with the amount of filler content.

• Advanced Composite Materials
• /
• v.17 no.3
• /
• pp.277-299
• /
• 2008

High quality and expedient processing repair methods are necessary to enhance the service life of bridge structures. Deterioration of concrete can occur as a result of structural cracks, corrosion of reinforcement, and freeze.thaw cycles. Cost effective methods with potential for field implementation are necessary to address the issue of the vulnerability of bridge structures and how to repair them. Most infrastructure related applications of fiber-reinforced plastics (FRPs) use traditional hand lay-up technology. The hand lay-up is tedious, labor-intensive and relies upon personnel skill level. An alternative to traditional hand lay-up of FRP for infrastructure applications is Vacuum Assisted Resin Transfer Molding (VARTM). VARTM uses single sided molding technology to infuse resin over fabrics wrapping large structures, such as bridge girders and columns. There is no work currently available in understanding the interface developed, when VARTM processing is adopted to wrap fibers such as carbon and/or glass over concrete structures. This paper investigates the interface formed by carbon fiber processed on to a concrete surface using the VARTM technique. Various surface treatments, including sandblasting, were performed to study the pull-off tensile test to find a potential prepared surface. A single-lap shear test was used to study the bond strength of CFRP fabric/epoxy composite adhered to concrete. Carbon fiber wraps incorporating Sikadur HEX 103C and low viscosity epoxy resin Sikadur 300 were considered in VARTM processing of concrete specimens.

• Design & Manufacturing
• /
• v.2 no.6
• /
• pp.23-27
• /
• 2008

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially when the family-mold has a volumetric difference between two cavities. In this study, the cavity-filling imbalance was confirmed by the temperature and the pressure sensors, and a variable-runner system was developed for balancing the cavity-filling. Experiments of balancing the cavity filling was carried out in the family-mold with the variable-runner system, and balancing the cavity-filling was confirmed by changing the cross-sectional area of a runner in the variable-runner system with the temperature and pressure sensors. The influence of the injection speed to the balancing-capability of the variable-runner system was also examined in the experiment.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.11
• /
• pp.4950-4955
• /
• 2012

A bolt manufacturing process is completed with continuous forging. Technical and economical success of each process will depend on the appropriate process design and metal mold design for each procedure. This study aims to analyze the moldings of first and second steps among the multi-step molding processes of SCM435 bolt by use of the finite element method in order to achieve the reasonable process. Since the processes of first and second steps analyzed by use of the finite element method consist of axial symmetry, the transformed configuration of material satisfy the dimensions expected in process. In addition, the uniflow line formed in material becomes smooth and consistent over the entire process. Therefore neither molding of material nor inherent defect is expected.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2092-2099
• /
• 2013

Through the data transfer race in industry since 1990s, the operational speed of optical disk drive(ODD) becomes commonly over 10,000 rpm. Such high speed operation inevitably causes the vibration, which is also the disturbances in the read-write process of pick-up servo-controller. Generally the vibration disturbance problem can be solved by the vibration isolation using the rubber mount and the increase of robustness of the pick-up servo-controller. Optical disk itself has not been targeted for the vibration reduction, because it is manufactured under the standardized format. In this paper we focused on the increase of critical speed of optical disk, that is, the improvement of dynamic characteristics, with the control of residual stresses which are come from the injection molding process. To do this, first, the residual stresses induced from the injection molding process are calculated using finite element method. The major design parameters of the process conditions are flow rate and melt temperature, which control the residual stresses in optical disk. Second, the critical speed of optical disk is calculated with modal analysis considering residual stress distributions. It was found out that the critical speed can be improved by the control of operational parameters in the injection molding process.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.2 no.2
• /
• pp.1-5
• /
• 2001

One of the major advantages of using engineering plastics is ease of part assembly through a locking mechanism known as a snap fit. The typical snap fit involves a short cantilever beam with a projection at the free end. which slides over a one way ramp on the mating part to lock in place. The tightness of the mechanism is determined by the lateral interference of the two sliding members If too small they become loose and can't hold together. while if too large. excessive force can be generated. causing failure of the cantilever beam during the assembly operation. Therefore. the accurate determination of the force-deflection relationship for cantilever beams is a key element in snap fit design. And also. the process of injection molding should be considered when cantilever beam is designed. But it is not easy for novice designers to design them appropriately because of the profound knowledge related to injection molding. In this paper. an intelligent design program has been developed and proposed to improve a conventional empirical design method.