• Title/Summary/Keyword: 3-dimensional packing

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A Study on the Injection Molding Analysis of the Metal Powder Material (금속분말재료의 사출 성형해석에 관한 연구)

  • Ro, Chan-Seung;Park, Jong-Nam;Jung, Han-Byul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.42-47
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    • 2017
  • In this study,we conducted an injection molding analysis of metal powder materials for the development of flanges, which are necessary adapters for optical communication. The metal powder injection molding process is a technique for producing an injection molded article having a complicated shape by mixing ceramic or stainless powder and binders. It is used to produce products which require complex processing technology or for which the productivity is low. The purpose of this study is to minimize the manufacturing processing of products which are manufactured through existing mechanical processing procedures. For the injection molding analysis, we mixed stainless STS316 metal powder with binders at a ratio of 6 to 4 to make molding materials consisting of granular pellets. Then, three-dimensional modeling and meshing were carried out to obtain the optimal injection molding analysis conditions(molding temperature, melting temperature, injection time, injection temperature, injection pressure, packing time and cooling time). As a result of the analysis, it was discovered that the inlet became available 13.29 seconds after the first injection. Also, as the flowing and packing in the melt through the sprue, runner and gate were stable, it is expected that good molds can be manufactured.

Determination of Molding Conditions of Double-Shot Injection Mold for the Computer Mouse via Three-Dimensional Injection Molding Analysis (3 차원 사출성형 해석을 통한 컴퓨터 마우스 제작용 이중사출성형 금형의 공정조건 결정)

  • Ahn, Dong-Gyu;Park, Min-Woo;Park, Jeong-Woo;Kim, Hyung-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.12
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    • pp.1619-1625
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    • 2011
  • The objective of this study determine the molding conditions of a double-shot injection mold for fabricating a computer mouse using different materials, by performing three-dimensional injection molding analysis. In order to select the optical injection molding conditions, the effects of the injection time, the maximum injection pressure, the effect of packing time on the injection molding characteristics, and the product qualities were quantitatively examined. From the results of the injection molding analysis, the optimal injection molding conditions of the double-shot injection mold, which leads the molded product to the minimized shrinkage and deflection, were estimated. The results of the injection molding experiments, showed that an appropriate computer mouse can be fabricated using different materials when the identified optimal injection molding conditions are adopted.

Delayed rupture of a posttraumatic retromaxillary pseudoaneurysm causing massive bleeding: a case report

  • Hwang, Jae Ha;Kim, Woo Hyeong;Choi, Jun Ho;Kim, Kwang Seog;Lee, Sam Yong
    • Archives of Craniofacial Surgery
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    • v.22 no.3
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    • pp.168-172
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    • 2021
  • Posttraumatic pseudoaneurysm of the face is caused by blunt, penetrating, or surgical trauma. Although its incidence is low, pseudoaneurysm rupture can cause a life-threatening, massive hemorrhage. A 48-year-old man visited our emergency center due to a fall-down accident. Three-dimensional computed tomography (CT) showed a comminuted zygomaticomaxillary complex fracture of the left face. After open reduction and internal fixation, the surgical wound healed without any complications. However, the patient was readmitted 10 days after surgery due to pus-like discharge from the wound. Contrast-enhanced CT to find the abscess unexpectedly revealed a pseudoaneurysm in the left retromaxillary area. Massive oral bleeding occurred on the night of re-hospitalization and emergency surgery was done. The bleeding site was identified as a pseudo-aneurysmal rupture of the posterior superior alveolar artery in the retromaxillary area. Hemostasis was achieved by packing Vaseline gauze in the maxillary sinus using an endoscope. Delayed rupture and massive bleeding of posttraumatic retromaxillary pseudoaneurysm after a zygomaticomaxillary fracture is a low-probability, but high-impact event. Therefore, additional contrast-enhanced CT should be considered to evaluate the possibility of a posttraumatic pseudoaneurysm in cases of severe comminuted zygomaticomaxillary fracture.

Trends in Materials Modeling and Computation for Metal Additive Manufacturing

  • Seoyeon Jeon;Hyunjoo Choi
    • Journal of Powder Materials
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    • v.31 no.3
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    • pp.213-219
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    • 2024
  • Additive Manufacturing (AM) is a process that fabricates products by manufacturing materials according to a three-dimensional model. It has recently gained attention due to its environmental advantages, including reduced energy consumption and high material utilization rates. However, controlling defects such as melting issues and residual stress, which can occur during metal additive manufacturing, poses a challenge. The trial-and-error verification of these defects is both time-consuming and costly. Consequently, efforts have been made to develop phenomenological models that understand the influence of process variables on defects, and mechanical/ electrical/thermal properties of geometrically complex products. This paper introduces modeling techniques that can simulate the powder additive manufacturing process. The focus is on representative metal additive manufacturing processes such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), and Binder Jetting (BJ) method. To calculate thermal-stress history and the resulting deformations, modeling techniques based on Finite Element Method (FEM) are generally utilized. For simulating the movements and packing behavior of powders during powder classification, modeling techniques based on Discrete Element Method (DEM) are employed. Additionally, to simulate sintering and microstructural changes, techniques such as Monte Carlo (MC), Molecular Dynamics (MD), and Phase Field Modeling (PFM) are predominantly used.

A Study on the Optimization of the Dimensional Deviation due to the Shortening of the Cycle Time for Rear Cover of Mobile Phone (휴대폰 후면 커버의 공정시간 단축에 따른 치수 편차의 최적화에 관한 연구)

  • Kim, Joo-Kwon;Kim, Jong-Sun;Lee, Jun-Han;Kwak, Jae-Seob
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.6
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    • pp.117-124
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    • 2017
  • In this study, we investigated the optimization of process conditions by using the Six Sigma process, design of experiment (DOE) method and response surface method (RSM) to resolve dimensional deviation and appearance problems arising from the shortened process time of the mobile phone rear cover. The analysis of the trivial many was performed by 2-sample T-test and cooling time, and mold temperature and packing pressure were selected as the vital fews affecting the overall width of the product. The optimal conditions of the process were then studied using the DOE and the RSM. We analyzed the improvement effects by applying the selected optimal conditions to the production process and the results showed that the difference between the mean value and target value of the overall width stood at 0.01 mm, an improvement of 88.89% compared to current process that fell within the range of standard dimension. The short-term process capability stood at $4.77{\sigma}$, which implied an excellent technology level despite a decrease by $0.22{\sigma}$ compared to the current process. The difference in process capability decreased by $2.44{\sigma}$ to $0.41{\sigma}$, showing a significant improvement in management capability. Ultimately, the process time of the product was shortened from 18.3 seconds in the current process to 13.65 seconds, resulting in a 34.07% improvement in production yield.

Reappraisal of Anatomic Outcome Scales of Coiled Intracranial Aneurysms in the Prediction of Recanalization

  • Lee, Jong Young;Kwon, Bae Ju;Cho, Young Dae;Kang, Hyun-Seung;Han, Moon Hee
    • Journal of Korean Neurosurgical Society
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    • v.53 no.6
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    • pp.342-348
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    • 2013
  • Objective : Several scales are currently used to assess occlusion rates of coiled cerebral aneurysms. This study compared these scales as predictors of recanalization. Methods : Clinical data of 827 patients harboring 901 aneurysms treated by coiling were retrospectively reviewed. Occlusion rates were assessed using angiographic grading scale (AGS), two-dimensional percent occlusion (2DPO), and volumetric packing density (vPD). Every scale had 3 categories. Followed patients were dichotomized into either presence or absence of recanalization. Kaplan-Meier analysis was conducted, and Cox proportional hazards analysis was performed to identify surviving probabilities of recanalization. Lastly, the predictive accuracies of three different scales were measured via Harrell's C index. Results : The cumulative risk of recanalization was 7% at 12-month, 10% at 24-month, and 13% at 36-month of postembolization, and significantly higher for the second and third categories of every scale (p<0.001). Multivariate-adjusted hazard ratios (HRs) of the second and third categories as compared with the first category of AGS (HR : 3.95 and 4.15, p=0.004 and 0.001) and 2DPO (HR : 4.87 and 3.12, p<0.001 and 0.01) were similar. For vPD, there was no association between occlusion rates and recanalization. The validated and optimism-adjusted C-indices were 0.50 [confidence (CI) : -1.09-2.09], 0.47 (CI : -1.10-2.09) and 0.44 (CI : -1.10-2.08) for AGS, 2DPO, and vPD, respectively. Conclusion : Total occlusion should be reasonably tried in coiling to maximize the benefit of the treatment. AGS may be the best to predict recanalization, whereas vPD should not be used alone.

Conservation Treatment and the Development of a Relics Filling Pad to Maintain the Shape of a Doctor's Coat Worn by Seo Jae-pil, the National Registered Cultural Heritage No. 607 (국가등록문화재 제607호 서재필 진료가운 보존처리와 유물 충전재 개발)

  • Lee, Ryangmi;An, Boyeon;Jun, Eunjin
    • Journal of the Korean Society of Clothing and Textiles
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    • v.45 no.3
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    • pp.409-422
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    • 2021
  • A doctor's coat worn by Seo Jae-pil (1864-1951)-National Registered Cultural Heritage No. 607-was conserved with wet cleaning to remove thick wrinkles and brown stains that had been present for a long time. This paper also applied microscopic observation and infrared spectrophotometric analysis to obtain scientific investigation data on the cotton fabric of this doctor's coat. Information about Seo Jae-pil's time as a doctor, the process of changing his English name, and C.D.Williams & Co., which produced the medical coat, revealed that this doctor's coat was worn by Seo Jae-pil between 1892 and 1898 or 1926 and 1939. Additionally, this paper proposes a pad for filling relics that can protect the shape of modern and contemporary clothing, such as Seo Jae-pil's doctor's coat, for display at a museum site. Specifically, this research provides detailed information on the manufacturing of filling pads that can prevent damage to modern and contemporary jackets and coats so that they can be used in the cultural heritage field by developing filling materials for three-dimensional costume artifacts.

Optimization of preform mold injection molding process for hemispheric plastic structure fabrication (반구형 플라스틱 구조체 성형을 위한 프리폼 몰드 사출성형공정 최적화)

  • Park, Jeong-Yeon;Ko, Young-Bae;Kim, Dong-Earn;Ha, Seok-Jae;Yoon, Gil-Sang
    • Design & Manufacturing
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    • v.13 no.2
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    • pp.30-36
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    • 2019
  • Traditional cell culture(2-dimensional) is the method that provide a nutrient and environment on a flat surface to cultivate cells into a single layer. Since the cell characteristics of 2D culture method is different from the characteristics of the cells cultured in the body, attempts to cultivate the cells in an environment similar to the body environment are actively proceeding in the industry, academy, and research institutes. In this study, we will develop a technology to fabricate micro-structures capable of culturing cells on surfaces with various curvatures, surface shapes, and characteristics. In order to fabricate the hemispheric plastic structure(thickness $50{\mu}m$), plastic preform mold (hereinafter as "preform mold") corresponding to the hemisphere was first prepared by injection molding in order to fabricate a two - layer structure to be combined with a flat plastic film. Then, thermoplastic polymer dissolved in an organic solvent was solidified on a preform mold. As a preliminary study, we proposed injection molding conditions that can minimize X/Y/Z axis deflection value. The effects of the following conditions on the preform mold were analyzed through injection molding CAE, [(1) coolant inlet temperature, (2) injection time, (3) packing pressure, (4) volume-pressure (V/P). As a result, the injection molding process conditions (cooling water inlet temperature, injection time, holding pressure condition (V / P conversion point and holding pressure size)) which can minimize the deformation amount of the preform mold were derived through CAE without applying the experimental design method. Also, the derived injection molding process conditions were applied during actual injection molding and the degree of deformation of the formed preform mold was compared with the analysis results. It is expected that plastic film having various shapes in addition to hemispherical shape using the preform mold produced through this study will be useful for the molding preform molding technology and cast molding technology.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.