판상형 충전제의 함량과 배향에 따른 PP복합체의 열팽창계수 영향 연구

이기윤(Kee Yoon Lee),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeoung),황효연(Hyo Yeon Hwang),이승구(Seung Goo Lee) 한국고분자학회 2012 폴리머 Vol.36 No.3

두 가지의 종횡비(ρα=a1/a3 and ρβ=a1/a2)에 의해 특징지어진 3차원 타원체(a1 > a2 > a3)를 사용하여 polypropylene 복합체의 판상형 충전제 함량과 방향이 열팽창률에 미치는 영향에 대해 실험적인 연구를 수행하였다. 측정된 실험적인 값은 Lee와 그의 연구자들이 제안한 이론적인 모델에 의한 계산 값과 비교분석되었다. 판상형충전제로는 운모와 탈크가 사용되었다. 실험 결과로 운모의 경우 종횡비는 ρα= 13.5, ρβ= 1.8이 사용되 어, 20 wt% 함량일때 α11/αm는 약 0.56으로 감소하였으나, α33/αm는 오히려 1.018로 증가함을 보였다. 탈크의 경우의 종횡비는 ρα=3.7, ρβ= 1.4이었고 α11/αm는 0.63으로 감소하였다. 결국 운모와 탈크 모두 그 함량증가에 따라 종단방향과 횡단방향에서 열팽창률은 감소하였으나 수직방향에서는 초기 낮은 충전제 함량에서는 오히려 증가하는 경향을 보였다. Experimental study was performed regarding the effects of disc-like filler orientation and contents on the coefficient of thermal expansion (CTE) of polypropylene composites using the three dimensional ellipsoids (a1 > a2 > a3) analyzed by two aspect ratios(ρα=a1/a3 and ρβ=a1/a2). Measured data were compared with the theoretical approaches proposed by Lee et al. Mica and talc were useed as disk-like fillers in the composites. As experimental results, α11/αm decreased down to ca. 0.56 with mica content of 20 wt% and the aspect ratios, ρα=13.5, ρβ=1.8. However, α33/αm increased to more than 1. In the case of talc, α11/αm decreased to ca. 0.63 with 20 wt% and ρα=3.7, ρβ=1.4. Finally, the longitudinal CTEs (α11) of polypropylene composites decreased as filler contents increased, but normal CTE (α33) increased in the low filler contents like the theory.

판상형 충전제의 함량과 배향에 따른 PP복합체의 영률 변화 연구

서상범(Sang Bum Seo),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeong),이승구(Seung Goo Lee),이기윤(Kee Yoon Lee) 한국고분자학회 2012 폴리머 Vol.36 No.2

이 논문은 판상형 충전제의 함량과 배향에 따라 폴리프로필렌 복합체의 영률 변화에 미치는 영향을 연구 하였다. 이론적인 예측은 Lee와 그의 연구자들에 의해 제안된 두 개의 종횡비, ρα=a1/a3과 ρβ=a1/a2 를 이용하여 3차원 타원체의 형상을 계산하였고 실험값과 비교 분석하였다. 판상형 충전제로 운모와 탈크를 사용하였다. 충전제의 형태는 SEM을 이용해 관찰하였고, 종횡비는 고분자의 흐름을 기준으로 좌표축을 설정하여 통계적 방법으로 계 산하였다. 충전제가 운모인 경우에 ρα=13.5와 ρβ=1.8이었고, 탈크의 경우는 ρα=3.8과 ρβ=1.4이었다. 또한 충전제 의 2개의 종횡비와 함량이 기계적 물성에 미치는 영향을 실험적으로 연구하였다. 운모의 경우 30 wt% 함량일 때 E11이 약 2.7배 향상되었다. 탈크의 경우는 E11이 약 2.3배 향상하였다. This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ρα=a1/a3 and ρβ=a1/a2 proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ρα=13.5 and ρβ=1.8, and for the case of talc, they were ρα=3.8 and ρβ=1.4. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, E11 increased up to about 2.7 times, and for the other case of talc, E11 increased up to about 2.3 times, respectively.

복잡한 해안지역의 지역특성을 고려한 대기 유동장에 따른 SO₂의 확산장 수치모의

이화운,원혜영,최현정,이강열,김현구 한국환경과학회 2005 한국환경과학회지 Vol.14 No.3

Recently air quality modeling studies for industrial complex and large cities located in the coastal regions have been carried out. Especially, the representation of atmospheric flow fields within a model domain is very important, because an adequate air quality simulation requires an accurate portrayal of the realistic three-dimensional wind fields. Therefore this study investigated effect of using high resolution terrain height data and FDDA with observational data to reflect local characteristics in numerical simulation. So the experiments were designed according to FDDA and the detail terrain height with 3sec resolution or not. Case 30s was the experiment using the terrain height data of USGS without FDDA and Case 3s was the experiment using the detail terrain height data of Ministry of Environment without FDDA and Case 3sF was experiment using the detail terrain height data of Ministry of Environment with FDDA. The results of experiments were more remarkable. In Case 3s and Case 3sF, temperature indicated similar tendency comparing to observational data predicting maximum temperature during the daytime and wind speed made weakly for difference of terrain height. Also Case 3sF had more adequate tendency than Case 3s at dawn.

대기오염 확산 해석을 위한 포항지역 기상장 연구 : 바람장 수치모의 Numerical Simulation of Wind Field

이화운,정우식,김현구,이순환 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.1

Sea/land circulation system is a representative mesoscale local circulation system in coastal area. In this study, wind fields around coastal area, Pohang, which is affected by this system was investigated and its detailed characteristic analysis was carried out. The following can be found out from the numerical simulation. Generally, at nighttime mountain winds prevail and land breeze toward the coastal area was well simulated. During daytime, valley wind and sea breeze was simulated in detail. Especially, as a result of analyzing the land breeze path, it could be found along the coastline as it flows out through low land coastal area. In order to investigate the accuracy of model results, wind speed, temperature and wind direction of continuous typical sea/land breeze occurrence day was compared with observation data. Analyzing the characteristics of local circulation system was very hard because of horizontally sparse observation data but from the above result, a numerical simulation using RAMS, which satisfies the spatial high resolution, will provide more accurate results.

CT-2 부가 데이터 서비스 연구

이양원,나현식,강민구 호남대학교 산업기술연구소 1998 산업기술연구논문집 Vol.6 No.-

CT-2는 기존의 셀룰라폰이 셀단위의 영역에서 이동통신을 행하는 것과 동일한 개념의 보행자 중심의 소형 경량의 발신전용 개인 휴대용 이동통신 장치이다. 본 연구에서는 이러한 CT-2 시스템의 발전과 부가서비스 연구를 위해 CT-3의 개념인 착발신이 가능한 서비스의 제공과 전국 로밍 기능, 기지국간의 이동이 가능한 핸드오버 기능 및 FPLMTS 망을 사용하여 무선 멀티미디어의 음성/데이터/화상 서비스를 제공하기 위한 양방향 무선호출과 연계와 같은 진화방향에 대한 연구한다.

SNMP를 이용한 무선 AP 관리 시스템 구현 및 분석

김현우,이구연 강원대학교 정보통신연구소 2008 정보통신논문지 Vol.12 No.-

Traffic through wireless LANs increases dramatically due to the increase of notebook and PDA users. Therefore, network administrators need to optimize wireless networks by analyzing user groups, traffic patterns according to locations to avoid network bottlenecks and overloads. In this paper, we implement a wireless access point(AP) management system using SNMP which monitors traffic load of each AP and redistributes heavy traffic among APs for load balancing. The system also does packet format analysis and detect packets containing special text patterns. We measure and analyze the traffic load of the implemented system and show that the system is very useful when a wireless network having many APs has heavy traffic.

環境放射能 測定 : 光州東部 地域을 中心으로 on the eastern part of Gwang Ju

金炫九,李官敎 조선대학교 원자력연구소 1981 原子力硏究 Vol.1 No.-

A systematic survey on the environmental radioactivity at Chosun University and its surrounding areas during the year of 1981 was carried out through various environmental samples, which were precipitation, surface soil, stream water, pine needles, and others. Out of these samples natural background radiation was surveyed. No significant radioactive materials from the Atomic Energy Research Institute attached to Chosun University and the Radioisotopes Laboratory of Chosun University Hospital were detected during this period.

정보기술수용모델(TAM)을 적용한 신용평가시스템의 실증적 연구 : On the Basis of TAM

최현호,박기남,이경구,김종원 대한경영학회 2003 大韓經營學會誌 Vol.16 No.5

Since International Monetary Fund (IMF), many Korean banks are using the Credit Risk Ratio System (CRRS) to systematically evaluate the borrower's credits. However, there are few research focusing on the key antecedents of successful CRRS utilization. Therefore, the purpose of this paper is to investigate the factors influencing individual intention to use and actual use of CRRS, and to analyze the relationships among those factors. Doing so, this study employs TAM (Technology Acceptance Model) proposed by Davis (1989) as a main framework. The results show that industry competition, diversity of customers' needs, organizational support, organizational experience, technical interchangeability, users' participation, and social norms make direct and/or indirect impacts on behavioral intention and actual use through perceived ease of use and perceived usefulness. The empirical findings from this study may prove useful for both IS researchers and practitioners.

디지탈 통신 학습 시뮬레이터

송현교,김연구,이택희,강민구 호남대학교 정보통신연구소 1995 정보통신연구 Vol.4 No.-

본 논문에서는 실제 통신망에서 발생할 수 있는 데이타 전송과정을 컴퓨터상에 시뮬레이션하는 프로그램으로서, PC의 WINSOW 환경하에서 Visual-Basic을 활용하여 통신신호의 흐름과정을 하나의 화면에서 구현하도록 부호화와 변조파형을 표현하고 이 신호의 복조와 복호과정을 시뮬에이션한다. 아울러 통신채널에서 발생하는 랜덤오류를 제어하는 오류정정을 포함함으로서 통신이론을 이해하고 학습하는데 많은 도움이 될 수 있도록 통신신호에 대한 그래픽 처리에 목적을 둔다. In this thesis, the graphic signal for communication is presented in the WINDOW using `Visual-Basic'. All signals of PCM encoding/decoding and modulation/demodulation are processed in the same picture. Especially, error control schemes which are parity check, longiudinal redundancy check, cyclic redundancy check, are described for more reliable communication.

Schiff Base에 의한 구리 부식 억제

정병구,이현석,장영학,문채주 木浦大學校 應用科學硏究院 2001 應用科學硏究誌 Vol.1 No.-

The inhibiting action of copper in 5% hydrochloric acid(HCI) solutions with or without Schiff base, 1,2-bis(naphthylideneimine)ethane(NET), 1,3-bis(naphthylideneimine) propane(NPR), 1,4-bis(naphthylideneimine)butane(NBU), and 1,5-bis(naphthylideneimine) pentane(NPE), has been studied by the Tafel method and AC impedance technique. The corrosion parameters were obtained at different inhibitor concentrations and the temperature effect was also investigated. The inhibiting efficiency increases with a decrease in temperature or increase in concentration of the Schiff base. NPE is the best inhibitor in this series and the maximum inhibition efficiency at a concentration of 5×10^-4 M at 298 K approached 90.07%. Schiff base with longer-chain are superior to shorter-chained analogues in inhibition efficiency.