충전과 보압과정이 사출성형공정에 미치는 영향에 관한 연구

김현필,김용조 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.4

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for the filling and packing phases. Molding troubles like flow mark, weld line, sink mark, short shot and warpage can be caused by these injection molding process factors. Among them, the short shot was caused by the fact that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition, as the flow rate for the volumetric shrinkage during the frozen phase could not be supplied properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing pressure.

카운터샤프트 기어의 스플라인 치형 정밀성형을 위한 열간단조 공정에 관한 연구

김현필,김현수,김용조,Kim, H.P.,Kim, H.S.,Kim, Y.J. 한국금형공학회 2012 한국금형공학회지 Vol.6 No.2

A counter shaft gear is an important part in the transmission system of vehicle. Its shape is relatively complicated and should meets high strength. Traditionally the counter shaft gear has been manufactured as follows; a spline body is firstly machined for teeth and then attached to the main gear body by frictional welding, and finally is finished by grinding. Therefore it is necessary to develop a new manufacturing technology eliminating both frictional welding and grinding processes. In this study, a new hot forging process was proposed and designed so that the spline body with teeth and main gear body are formed as one body. Finite element simulations and experimental works were peformed for design of forging processes to get the quality final precision-forged product. Consequently the most suitable blocker process could be obtained.

카운터샤프트 클러치 기어의 정밀성형 공정 개발

김현필,김용조,Kim, H.P.,Kim, Y.J. 한국금형공학회 2012 한국금형공학회지 Vol.6 No.2

A counter shaft gear is an important part in the transmission system of vehicle. Its shape is relatively complicated and should meets high strength. Traditionally it has been manufactured as follows; the counter shaft gear has consisted of a clutch and helical body with teeth which are forged and machined for teeth respectively and then attached by frictional welding. In this study, a new hot forging process was proposed and designed so that the counter shaft gear is formed as one body without divide it into two parts. Furthermore, the precision forging process has been developed for the clutch teeth without additional grinding.

효과적인 웰드라인 제어를 위한 사출셩형 유동해석

김현필,김용조 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.2

Weld line is one of serious troubles which are observed in a plastic part manufactured by a injection molding process. This is caused by mane process factors, which are molding pressure, temperature, velocity, location of a injection gate, mold geometry and material properties. Investigation on the effects of these process factors to the appearance of a weld line was carried out using a finite element method. Filling and packing analyses were carried out by modifying both the configuration of the injection gate; and cavity thickness. Proper locations of the injection gates could he determined by considering molding pressure, temperature, velocity and frozen layer, and whereby the weld line was controled. In order to make a weak appearance of the weld line, flow velocity and flow front in a cavity were also investigated by modifying a cavity thickness. As a result, floss flow was extended around the comer in the cavity by changing the flow velocity and hence the appearance of the weld line was much weakened.

SDR(Software Defined Radio)에 적합한 네트워크 코프로세서 구조의 설계

김현필,정하영,함동현,이용석 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.2

SDR(Software Defined Radio)에 적합한 네트워크 코프로세서 구조의 설계

김현필,정하영,함동현,이용석,Kim, Hyun-Pil,Jeong, Ha-Young,Ham, Dong-Hyeon,Lee, Yong-Surk 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.2A

디지털 컨버전스가 이루어지면서 무선기기들 간의 호환성은 단말기의 중요한 특성이 되었고, SDR은 가장 필요한 기술이고 표준이다. 하지만 통신 프로토콜이 다른 무선 환경에서 호환성을 갖는 단말기를 하드웨어만을 이용한 ASIC이나 SoC로 만들기는 어려운 실정이다. 그래서 본 논문은 여러 통신 프로토콜을 가속화 시킬 수 있는 코프로세서의 구조를 제안하였다. 메인 프로세서와 쉽게 연동이 되고, 네트워크의 PHY 레이어에 특화된 코프로세서가 바로 그것이다. 통신 시스템에서 가장 많이 사용하는 변조 방식인 OFDM과 CDM을 사용하는 무선 랜 표준 IEEE802.11a와 IEEE802.11b를 모델링한 C 프로그램을 ARM cross 컴파일러를 이용해 컴파일 하였고, Simplescalar-Arm 버전을 이용해 시뮬레이션 및 프로파일을 수행하였다. 프로파일 결과 비터비 연산과 부동 소수점 복소수 연산이 가장 많은 연산을 차지하였다. 프로파일 결과를 바탕으로 비터비 연산과 부동 소수점 복소수 연산을 가속화 할 수 있는 코프로세서를 제안하여 명령어를 추가했으며, 추가된 명령어는 Simplescalar-Arm 버전을 이용해 시뮬레이션 하였다. 시뮬레이션 결과 ARM 코어 하나만 사용 했을 때보다 비터비 연산은 약 4.5배, 부동 소수점 복소수 연산은 약 2배의 성능 향상을 보였다. IEEE802.11a에서는 일반 ARM 코어보다 약 3배의 성능 향상을 보였고, IEEE802.11b에서는 약 1.5배의 성능 향상의 보였다. In order to become ubiquitous world, the compatibility of wireless machines has become the significant characteristic of a communication terminal. Thus, SDR is the most necessary technology and standard. However, among the environment which has different communication protocol, it's difficult to make a terminal with only hardware using ASIC or SoC. This paper suggests the processor that can accelerate several communication protocol. It can be connected with main-processor, and it is specialized PHY layer of network The C-program that is modeled with the wireless protocol IEEE802.11a and IEEE802.11b which are based on widely used modulation way; OFDM and CDM is compiled with ARM cross compiler and done simulation and profiling with Simplescalar-Arm version. The result of profiling, most operations were Viterbi operations and complex floating point operations. According to this result we suggested a co-processor which can accelerate Viterbi operations and complex floating point operations and added instructions. These instructions are simulated with Simplescalar-Arm version. The result of this simulation, comparing with computing only one ARM core, the operations of Viterbi improved as fast as 4.5 times. And the operations of complex floating point improved as fast as twice. The operations of IEEE802.11a are 3 times faster, and the operations of IEEE802.11b are 1.5 times faster.

베타딘과 과산화수소수가 혈관경련에 미치는 영향

김현필,한승규,우홍서,김우경 大韓成形外科學會 2001 Archives of Plastic Surgery Vol.28 No.6

보스부분 사출성형의 싱크마크 발생에 관한 연구

김현필,김용조,Kim, Hyun-Pil,Kim, Yong-Jo 한국금형공학회 2008 한국금형공학회지 Vol.2 No.4

Supplementary features in injection molded products, which are boss, rib and snap fit, are mainly located in the products. These features might make molding flow improper in injection processing and consequently give rise to some of molding troubles such as short shot and hesitation. The sink mark on boss parts is generated by the volumetric shrinkage that is caused by both the molding thickness and the closed boss height. The volumetric shrinkage is affected by packing pressure and its amount tends to decrease by increasing the packing pressure. The packing pressure can therefore increase flow rate to a boss part and causes the sink mark depth to increase. As the molding thickness and the closed boss height in the boss part can increase the part volume, these may yield bad solidifying and also extend the molding cycle. In this paper, both the injection molding test and the flow analysis were carried out to investigate the effect of sink marks generated in the boss part of injection molded products.

사출성형에 대한 충전과 보압과정의 영향에 관한 연구

김현필,김용조 한국생산제조학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.4

보스 벽 두께가 사출성형의 싱크마크 발생에 미치는 영향

김현필,김용조,Kim, H.P.,Kim, Y.J. 한국금형공학회 2012 한국금형공학회지 Vol.6 No.1

The sink mark on boss parts is generated by the volumetric shrinkage that is caused by both the molding thickness and the boss wall thickness. The volumetric shrinkage is caused by packing pressure and its amount tends to decrease by increasing the packing pressure. The packing pressure can therefore increase the flow rate to a boss part and causes the depth of sink mark to increase. As the molding thickness and the boss wall thickness in the boss part can increase the part volume, these may yield bad solidifying and also extend the molding cycle. In this paper, both the injection molding test and the flow analysis were carried out to investigate the effect of sink mark that was generated in the boss wall thickness of injection molded products. The sink mark could also be caused by thickness ratio of boss part. For a given thickness ratio of boss, several molding process parameters such as packing pressure, packing time and melt temperature, affecting to generation of the sink mark were discussed.