• 한국염색가공학회지
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• 제32권4호
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• pp.245-254
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• 2020

The sheet molding compound composite has been applied divers section. This paper reports processing of carbon fiber reinforced thermosetting composite with diverse resins and which was composed of chopped carbon fiber (30 ~ 60 wt%). Normally the paste that the viscosity is over 15,000 cps has been used in traditional Sheet molding compound (SMC) machine. In this research, SMC machine was designed to make Carbon-sheet molding compound (C-SMC) prepreg which was composed with low viscosity resin (1,800 ~ 2,500 cps increase up to 10,000 cps after aging). In order to confirm the optimal processing condition. Mechanical strength tests including tensile test, shear test, impact test, flexural strength test were conducted on C-SMC composites. Plus we identified the correlation between the mechanical properties and prepreg processing condition (carbon ratio and applied resin).

• Design & Manufacturing
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• 제15권4호
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• pp.8-13
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• 2021

A plastic roller for opening and closing the safety door of the injection molding machine was molded. The dimensional change of the measurement position of the roller was studied when the cooling time was applied differently among the molding conditions, and when the temperature of the coolant applied for mold cooling was also applied differently. Cooling times of 300 seconds and 400 seconds, hot and low-temperature coolant were applied. When the low-temperature coolant was applied, the measuring point of the roller shrank by 0.03 mm. However, when the high-temperature coolant was applied, the measuring point shrank by 0.3 mm. It was found that the application of low-temperature coolant among coolants was more suitable for the reference dimension of the molded article compared to the application of high-temperature coolant. Among the cooling water applied for the molding of plastic rollers, when high-temperature coolant is applied, the shrinkage rate measured immediately after ejection was smaller than when low-temperature coolant is applied. However, it was found that post shrinkage, which occurs over time, occurs much larger when high-temperature coolant is applied.

• 정보저장시스템학회논문집
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• 제3권3호
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• pp.149-153
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• 2007

Perpendicular patterned magnetic media have been regarded as a prime candidate to achieve an ultra-high magnetic recording density of over 1 Tera-bits/$inch^2$. Patterned magnetic media with nanoscale patterns have been fabricated using various nanopatterning technologies. We focused on the two technical issues of nanoinjection molding technology. Firstly, we have investigated a cost-effective method to fabricate metallic stamps. Secondly, we focused on the analysis of nanoinjection molding with passive heating, where the replication of 50 nm nanopillar arrays was successful. The effect of the thermal insulation layer on the replication quality was examined by analytical and experimental methods. Finally, we deposited a magnetic layer on a injection molded nanopillars and measured. Our methodology can provide cost-effective mass-production for patterned magnetic media.

• 한국생산제조학회지
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• 제22권3호
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• pp.356-363
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• 2013

Mechanical molding press which is used for transformation process during semiconductor manufacturing process has structural deformations by pressure. If these deformations have over limit range, life of the press itself can be reduced and it will be exerted on a bad effect for quality of the semiconductor. In this research, the main plates and links of a press are analyzed in relation to the structural deformations caused by pressure excluding thermal deformations. After modifying the modeling, the analysis is performed again to determine optimal design of the press, and this design is introduced to ensure that most of the stresses on the main plates are within safe allowable limits. As a result, an optimal design method for the structure is investigated to produce the desired pressure even when the size of the main structure is minimized.

• 소성∙가공
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• 제21권2호
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• pp.126-130
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• 2012

Accurate optical texturing of light guide plate over the entire surface area is an important technical issue in LCD TV industry. Injection molding process has the potential to produce large light guide plates having highly efficient optical textures such as micro-prism array. This study is focused on the effect of the degree of replication of the micro texture of the 40" injection molded light guide plates on the overall optical performance of the display panel. Measured replication ratios of the micro-textures formed with three different types of injection molding process were considered in the modeling of prismatic micro segment array. Optical simulation was conducted and results were discussed.

• 한국기계가공학회지
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• 제11권2호
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• pp.60-65
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• 2012

This paper deals with an CAE analysis and optimization of injection molding for a mobile phone cover. Two design goals are established in the optimization; one is to switch over the feed system from cold runner to hot runner for the purpose of reducing material costs, and the other is to minimize the warpage in order to improve product quality. By the full-factorial experiments for design parameters, we showed that the cold runner design could be changed to the hot runner design by replacing the current resin with a new resin of higher fluidity. In addition, we could significantly reduce the warpage of the cover product under the hot runner system by optimizing packing pressure and packing time.

• 한국자동차공학회논문집
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• 제2권6호
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• pp.110-116
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• 1994

In this research, the tensile strength of molded parts and pressure distribution were analyzed to study the cavity filling stage and packing stage in injection molding. The measurement of cavity pressure was obtained by a data acquisition system with the installation of transducers in the cavity. Molded parts were tested by a universal testing machine to obtain the tensile strength. For the experimental work, the tensile strength of molded parts increased with longer packing time and exact freezing time of the gate was obtained by a cavity pressure curve. In addition, the effect of packing did not occur and tensile strength was almost constant after early 1.5 sec of the freezing time of gate. Density tended to be higher about 0.2% due to a larger degree of mold temperature and melt temperature. Also, changing pressure in the cavity was effectively sensed. Thereafter, the possibility of the development of pattern recognition expert system was confirmed on the basis of the experimental results.

• 대한기계학회논문집
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• 제19권6호
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• pp.1490-1500
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• 1995

Compression molding of SMC (Sheet Molding Compound) in a thin plaque with substructures like a rib is involved with the formation of surface defect along the centerline over the rib area called by sink mark depending on process parameters. The surface quality of the external panels in automotive manufacturing is so critical that this kind of defect should be eliminated during manufacturing stages. The effect of process parameters on sink mark formation and the distribution of chopped fiberglasses in the compression molded thin plaque with a rib was experimentally investigated in the present study. In order to estimate the effect of the molding parameters such as molding temperature, mold closing speed, depth of the rib, corner radius of the rib, and final molded part thickness of flat portion on the depth of sink mark and the distribution of fiberglasses in the molded SMC part with the rib under the present experimental conditions, the molding parameters used in experiments were non-dimensionalized equation for predicting the depth of sink mark was determined through dimensional analysis based on the experimental data. The orientation and distribution of fiberglasses and fillers which directly affect the formation and depth of sink mark were investigated by taking the photographs of the cross-sectional area of the molded specimen using scanning electron microscope. The experimental results proposed from this investigation are useful in understanding the formation of sink mark and predicting the depth of sink mark in compression molding of SMC with substructures.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1773-1785
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• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• 한국환경생태학회지
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• 제20권4호
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• pp.436-447
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• 2006

임도를 비롯한 각종 훼손지 비탈면에서 종자뿜어붙이기 공법에 의한 녹화효과를 제고하기 위해서 참싸리, 낭아초, 새, 켄터키 블루그래스, 페러니얼 라이그래스를 재료로 하여 종자피복 및 복토 여부에 따른 종자발아 및 유묘의 생장특성을 조사하였다. 그 결과를 요약하면 다음과 같다. 1. 모든 시험식물에서 종자의 피복처 리는 무피복에 비해 복토파종과 겉뿌림에서 모두 종자의 발아율을 향상시 켰다. 종자피복에 의해 전체 평균 발아율은 복토파종과 겉뿌림에서 각각 11.2%와 21.4% 향상되었다. 또한 발아세는 식물종과 처리에 따라 $0.8{\sim}3.7$일 단축시켰고, LD50은 $0.8{\sim}2.6$일 단축시키는 효과가 있었다. 그러나 모든 시험식물에서 종자피복에 의해 발아개시 일은 1일 이 내에서 지연되었다. 2. 종자피복은 식물의 지상부와 뿌리의 생장을 촉진시키는 효과가 있었다. 즉 종자피복에 의해 전체 평균 지상부생장은 복토파종과 겉뿌림에서 각각 21.7%와 34.8%향상되었고, 전체 평균 뿌리 생장은 복토파종과 겉뿌림에서 각각 22.0%와 26.2% 향상되었다. 3. 피복종자를 복토파종한 것은 겉뿌림 에 비해 발아 개시 일을 평균 1.3일 지 연시 켰으나, 발아율을 평균 5%향상시켰고, 발아세와 LD50을 각각 1.0일과 1.4일 단축시켰다. 그러나 종자피복에 의한 종자발아와 유묘생장의 향상효과는 복토파종에서보다 겉뿌림에서 더 크게 나타났다. 4.종자 피복재료 중에서는Vermiculite+Talcum가 시험식물의 종자발아와 유묘생장에 있어서 가장 효과가 좋았다. Bentonite, Calcium Carbonate, Calcium Hydroxide을 이용한 종자피복도 무피복에 비해 좋은 효과를 나타내었다. 5. 5종의 시험식물 가운데서 종자피복을 통한 발아향상효과는 낭아초에서, 유묘생장 촉진효과는 참싸리에서 가장 크게 나타났다. 즉 크기가 작은 초본류의 종자보다는 크기가 큰 목본류의 종자에서 종자픽복의 효과가 크게 나타났다. 6. 따라서 종자뿜어붙이기 공법으로 파종한 후에 복토를 할 수 없는 훼손지 비탈면에서는 녹화용 식물의 종자를 Vermiculite+Talcum 등으로 피복하여 파종함으로써 안정적 인 조기녹화를 실현할 수 있을 것으로 판단된다.