• 한국산학기술학회논문지
• /
• 제7권3호
• /
• pp.271-277
• /
• 2006

사출 성형 공정은 저비용으로 고품질의 제품을 대량으로 얻을 수 있는 제조 공정이지만. 성형품의 품질에 영향을 주는 인자의 수가 너무 많아 모든 경우에 대하여 실험을 수행하는 것은 시간적, 경제적으로 불가능하다. 따라서 최근에 시뮬레이션 도구를 활용하여 이러한 실험을 보조하고 있고, 실험계획법 및 여러 가지 최적화 기법들이 다루어지고 있다. 인자수가 많은 경우 각 입력인자 간의 교호작용 등도 고려하면서도 실험 횟수를 줄이는 기법으로 정립된 실험계획법을 적용하여 시뮬레이션 소프트웨어를 이용한 모의 실험 데이터를 도출하였으며, 이를 바탕으로 주변의 잡음에서도 강건한 설계를 할 수 있는 다구찌 기법을 사출 성형 공정에 적용하여 최적의 사출 성형 공정 조건을 나타내었다.

• 해양환경안전학회지
• /
• 제18권4호
• /
• pp.360-364
• /
• 2012

전기추진시스템 분야에서 AC/DC 컨버터는 상대적으로 간단한 다이오드 소자를 이용하는 정류기가 가장 널리 사용되고 있으며 이 정류기는 입력 전류에 큰 고조파를 포함하고 있어서 고조파 저감을 위한 많은 연구가 진행되고 있다. 본 연구에서 제안된 방식은 다이오드 정류기의 출력 전류를 정류기와 추진전동기 입력측에 주입하여 정류기와 추진전동기 입력 전류에 포함되는 고조파 성분을 줄이고 또한, 와이-델타 변압기를 정류기 및 추진전동기 입력회로에 설치되는 전류주입장치의 분배회로에 사용하여 주입전류와 전원 및 부하를 서로 절연함으로써 전류파형 개선과 전기적 안전성을 확보하였다. 제안한 방법을 현재 사용 중인 전기추진선박에서 적용하여 시뮬레이션 하였으며 기존의 전력변환장치와 비교하여 그 타당성을 입증하였다.

• Journal of Korean Neurosurgical Society
• /
• 제29권9호
• /
• pp.1209-1214
• /
• 2000

Objectives : The measurement of resistance to cerebrospinal fluid outflow($R_o$) can clearly delineate cerebrospinal fluid dynamics in patients with ventricular dilatation and can help in selecting patients to undergo shunt placement. With regards to type of infusion method, bolus injection is known to be more practical and safer than continuous infusion. The purpose of this study was to obtain $R_o$ of normal adults using lumbar bolus injection method. Material and Methods : Twenty adults aged 25 to 52 years were studied using lumbar bolus injection method. Fifteen patients with hemifacial spasm and five with cerebral concussion underwent $R_o$ measurement under propofol general anesthesia and local anesthesia, respectively. Results : The mean values of $R_o$ determined 1 minute and 2 minutes after bolus injection were $4.8{\pm}1.7$ and $4.4{\pm}1.6mmHg/ml/min$, respectively. There was no significant difference of $R_o$ between propofol general anesthesia group and local anesthesia group. Two patients showed $R_o$ greater than 6mmHg/ml/min. One patient revealed unexpectedly high level of $R_o$ due to severe spinal stenosis. Conclusion : Mean Ro in this study was higher than that of Shapiro's study. Borderline Ro near 6mmHg/ml/min should be regarded with caution and compared with clinical symptoms and results of other studies. Patients with severe spinal stenosis should be evaluated with caution.

• 한국정밀공학회지
• /
• 제31권7호
• /
• pp.561-567
• /
• 2014

Precision injection mold is an essential element in order to manufacture small and precision plastic lenses used for phone camera. There are many critical factors to meet the requested specifications of high quality plastic lenses. One of the main issues to realize high quality is minimizing decenter value, which becomes more critical as pixel numbers increases. This study suggests the method to minimize decenter value by modifying ejecting structure of the mold. Decenter value of injection-molded lens decreased to 1 ${\mu}m$ level from 5 ${\mu}m$ by applying suggested ejecting method. Also, we also developed BIS (Built-in Sensor) based smart mold system, which has pressure and temperature sensors inside of the mold. Pressure and temperature profiles from cavities are obtained and can be used for deduction of optimal injection molding condition, filling imbalance evaluation, status monitoring of injection molding and prediction of lens quality.

• 한국자동차공학회논문집
• /
• 제9권5호
• /
• pp.96-104
• /
• 2001

The present study experimentally investigates the concentration distribution of liquid and vapor phase with different injection timings in the in-cylinder flow field of a optically accessible engine. The conventional MPI, DOHC engine was modified into DI gasoline engine. The images of liquid and vapor phases in the motoring engine were captured by using exciplex fluorescence method. Dopants used in this study were 2% fluorobenzene and 9% DEMA(diethyl-methyl-amino) in 89% solution of hexane by volume respectively. Two dimensional spray fluorescence images of liquid and vapor phases were acquired to analyze spray behaviors and fuel distribution in the in-cylinder flow field. Measurements were carried out fur four different injection timings, namely BTDC 270$^{\circ}$, 180$^{\circ}$, 90$^{\circ}$, and 50$^{\circ}$. Experimental results indicate that behaviors and distribution of vapor phase were largely affected by in-cylinder tumble flow, and mixture formation process was also greatly affected by in-cylinder flow at early injection mode and by ambient pressure at late injection mode.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 지반공학 공동 학술발표회
• /
• pp.581-590
• /
• 2005

The grouting method is widely used as the impermeable effect and ground reinforcement in construction. But, it has a problem that cement and grout material are not mixed well in the injection tip equipment and an opposite flow and interception state of the chemical grouting is happened. so, continuous work is difficult. McG method installed a special grouting and device, made possible go well mixing of grouting material and prevent flowing backward and block of nozzle also diversify powder rate of cement that is grouting material to select sutible material in layer conditions. YSS that lowered $Na_2O$ influencing durability and circumstance is developed by gel-forming reaction material. so eco-circumstance and durability is increased by minimizing dissolution of underground water. In this study, it is assumed that seepage state of the injection material using a special injection tip equipment and a unconfined compressive strenth by mixing a various injection material of various. And it is confirmed that strenth increase effect and permeable decrease of the improved body through the test execution and field execution.

• 한국정밀공학회지
• /
• 제20권5호
• /
• pp.225-231
• /
• 2003

The injection molding is a traditional manufacturing method that can make plastic parts by just one time in mold. Therefore, the injection molding has become one of a manufacturing method, which is widely applied in a producing of plastic products. Nowadays, to use of plastic parts has increased and plastic product-model using term has been shorten. By these reasons, using term of a injection mold has fast been reduced. These produced molds will be disused and leaved in a storage after a regular term to use it. These leaved molds are sometime sold as scrap iron. But, these molds have lots parts for recycling except special parts for example, cavities, cores and eject pins, etc. In this research, we investigated when the cavity and core of in injection mold would be changed, the injection mold could be recycled. We suggested the structures and standardizations for recycling of a moldbase. We also developed a program in which can be used when the recycling moldbase design in the Auto-CAD with the recycling standards. We called this program as the Recy-Mold. For the availability of the program and moldbase structure fur the recycling standards, we experimented a used mold for automobile lens, which was remanufactured by the recycling standard. The results of this test showed feasibility for the recycling mold.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.472-477
• /
• 2003

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston cavity diameters in a optically accessible engine. The images of vapor phases were measured in the motoring engine using exciplex fluorescence method. The conventional engine was modified as GDI engine with swirl flow. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure is 5.1MPa. Two dimensional spray fluorescence image of vapor phases was acquired to analyze spray behavior and fuel distribution inside of cylinder. Three injection timings were set at BTDC $180^{\circ}$, $60^{\circ}$and $60^{\circ}$. With a fuel injection timing of BTDC $60^{\circ}$, fuel-rich mixture was concentrated in near the cavity center. With a fuel injection timing of BTDC $60^{\circ}$, fuel-rich mixture level in the center region was highest in the S-type during the late compression stroke. With a fuel injection timing of BTDC $180^{\circ}$, fuel was not affected in a piston cavity and generally distributed as homogeneous mixture.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 추계학술대회논문집
• /
• pp.54-57
• /
• 2004

Almost all injection molds have multi-cavity runner for mass production, which are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have sometimes been observed. These filling imbalances have historically been considered as result of uneven mold temperature and mold deflection, but it actually results from non-symmetrically shear, pressure, temperature distribution within melt material as it flows through the runner system. Filling imbalance could be decreased by modifying processing conditions that are related to shear, pressure, temperature such as injection rate, mold temperature, injection pressure, melt temperature. In this study, a series of experiment was conducted using Taguchi method to determine which processing condition influence as the primary cause of filling imbalance in geometrically balanced runner system. As a result of experiments, this paper could present an optimal processing condition to minimize variable that brings about filling imbalance geometrically balanced runner system

• 한국분말재료학회지
• /
• 제22권1호
• /
• pp.1-5
• /
• 2015

Powder injection molding is an important manufacturing technology to mass produce superalloy components with complex shape. Injection molding step is particularly important for realizing a desired shape, which requires much time and efforts finding the optimum process condition. Therefore computer aided engineering can be very useful to find proper injection molding conditions. In this study, we have conducted a finite element method based simulation for the spiral mold test of superalloy feedstock and compared the results with experimental ones. Sensitivity analysis with both of simulation and experiment reveals that the melt temperature of superalloy feedstock is the most important factor for the full filling of mold cavity. The FEM based simulation matches well the experimental results. This study contributes to the optimization of superalloy powder injection molding process.