Synthesis, Dispersion, and Tribological Performance of Alkylfunctionalized Graphene Oxide as an Oil Lubricant Additive and Synergistic Interaction with IF-WS2

한종석,최진영,유민,이창섭 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.5

Graphene and inorganic fullerene-type WS2 structures (IF-WS2) are two-dimensional (2D) materials with excellent lubricant property. They reduce the friction between contact surfaces. However, graphene is synthesized as a form of graphene oxide (GO) with a number of oxygen functional groups occurring on the surface, due to which it is difficult to use as a hydrophobic lubricant. Thus, this study synthesized functionalized graphene oxide (FGO) by attaching the alkyl chain to the surface of GO. The synthesized FGO enhanced the lipophilic property due to the alkyl chain. In addition, 1-methyl-2,4-bis(N-octadecylurea)benzene (MOB) was synthesized and added as a gelator to improve the durability of the dispersion. FGO was synthesized via two-stage reaction in which the alkyl chain was introduced by reacting with alkyl chloride after modifying GO to NH2-GO. MOB was synthesized by reacting with octadecylamine and toluene-2,4-diisocyanate. To analyze the morphology, microstructure, and functional groups of GO, FGO, and IF-WS2, scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy were performed. To analyze the binding energy, X-ray photoelectron spectroscopy was performed. X-ray diffraction and Raman spectroscopy were conducted for crystalline analysis. The synthesized FGO, WS2, and MOB were added to polyalphaolefin4 (PAO4) and distributed via ultrasonic processing. The friction characteristics were analyzed with the four-ball test and high-frequency friction/wear tester. The lubricant, which was gelated by adding MOB, maintained dispersion even after 30?days. The wear track size and friction coefficient of PAO4 oil containing 0.1 wt % FGO6, 1 wt % IF-WS2, and 1 wt % MOB were reduced by 21% and 13%, respectively, compared with those of PAO4 oil lacking the solid lubricant, which verified the improved wear resistance. The characteristics of tribology were also improved due to the synergistic interaction between FGO and IF-WS2.

Xcent 크로스바 라우팅 스위치 구현 ( Implementation of the Xcent Crossbar Routing Woo Jong Han )

한종석,박경,심원세,한우종 대한전자공학회 1997 대한전자공학회 학술대회 Vol.1997 No.11

고속 중형 컴퓨터의 버스 정보 처리기 설계 ( A Design of the Bus Information Processing Unit the TICOM-3 )

한종석,송용호,기안도 대한전자공학회 1994 대한전자공학회 학술대회 Vol.1994 No.11

정지궤도 위성과 지구국간 광통신 링크의 전송속도 해석

한종석,정진호,김영권,Han, Jong-Seok,Jung, Jin-Ho,Kim, Yung-Kwon 한국전기전자학회 1997 전기전자학회논문지 Vol.1 No.1

정지궤도 위성과 지구국간 광통신을 대기상태와 앙각의 함수로써 해석할 수 있는 한모델(Han's model)을 제시하였다. 한모델에서는 대기상태를 맑은날, 구름낀 날, 안개, 헤이즈, 비, 눈의 여섯가지 전형적인 상태로 구분한다. 비트오류을 $10^{-7}$을 만족하는 데이터 전송속도를 한모델을 이용하여 상향링크와 하향링크에 대해 해석하였다. 상향링크시의 포인팅손실이 하향링크시의 대기에 의한 공간 가간섭 저하보다 크기 때문에 데이터 전송속도는 하향링크 보다 오히려 상향링크시에 제한됨을 알 수 있었다. Han's model, which is able to analyze optical communication between earth station and geo-satellite as a function of atmospheric conditions and elevation angles. is presented. In Han's model, atmospheric conditions are roughly classified into six basic types; clear sky, cloud, haze, fog, rain and snow. Data rate satisfying for the BER below $10^{-7}$ is analyzed by Han's model in case of up-link and down-link, respectively. Data rate is more limited by up-link than by down-link because the pointing loss caused by atmosphere on the up-link is greater than the spatial coherence degradation caused by atmosphere on the down-link.

고속 중형 컴퓨터 통합 시험 및 성능 분석을 위한 버스 감시기의 설계 및 구현

한종석,송용호 대한전자공학회 1995 전자공학회논문지-B Vol.b32 No.8

On a bus-based shared memory multiprocessing system, the system bus monitoring and analysis are crucial for system integration test and performance analysis. In this paper, the design and implementation of a bus monitoring instrument for the TICOM-III system are decribed. The instrument dedicated to TICOM-III, which is called the Bus Information Procssing Unit, analyzes the bus state and measures the bus utilization. It performs many useful functions to help debugging the system, and offers a simple user interface.

이진 위상-주파수 검출기와 카운터를 이용한 디지털 위상 고정 루프 회로 설계

한종석,윤관,강진구,Han, Jong-Seok,Yoon, Kwan,Kang, Jin-Ku 한국전기전자학회 2012 전기전자학회논문지 Vol.16 No.4

본 논문은 이진 위상-주파수 검출기와 카운터를 사용한 새로운 위상-디지털 변환기 구조의 디지털 위상 고정 루프 회로를 제안하였다. 제안한 디지털 위상 고정 루프 회로는 위상-디지털 변환기, 디지털 루프, 디지털 제어 발진기(DCO)로 구성되어 있다. 제안된 위상-디지털 변환기 구조는 일반적인 시간-디지털 변환기(TDC)를 사용하지 않고, 이진 위상 주파수 검출기와 카운터를 사용함으로써 단순한 구조와 적은 면적으로 소비전력을 감소하는 장점을 갖는다. CMOS 0.18um 공정을 사용하여 1.0GHz에서 2.2GHz에 동작하는 디지털 위상 고정 루프 회로를 설계하였고 칩 면적은 $0.096mm^2$을 차지한다. 시뮬레이션 결과 전력소비는 1.65GHz 동작시 16.2mW로 나타났다. In this paper, a digital phase-locked loop(Digital-PLL) circuit with a new phase-to-digital converter(P2D) is described. The proposed digital PLL is composed a P2D, a digital loop filter(DLF), and a digitally controlled oscillator(DCO). The P2D generates a digital code for a phase error. The proposed P2D used a binary phase frequency detector(BPFD) and a counter in place of a time-to-digital converter(TDC) for simple structure, compact area and low power consumption. The proposed circuit was designed with CMOS 0.18um process. The simulation shows the circuit operates with the 1.0 to 2.2GHz with the power consumption of 16.2mW at 1.65GHz and the circuit occupies the chip area of $0.096mm^2$.

셀손실과 셀오류에 따른 MPEG-2의 주관적 QoS 성능

한종석,김영권,Han, Jong-Seok,Kim, Yung-Kwon 한국전기전자학회 1999 전기전자학회논문지 Vol.3 No.1

ATM 망을 이용한 MPEG-2 화상 서비스 제공 시 망에서 발생하는 셀손실과 셀오류에 따른 서비스 품질의 저하를 사용자의 주관적인 관점에서 평가하여 CLR, CER과 MPEG-2 비디오의 주관적인 QoS 간의 관계를 연구한다. NEM모듈을 이용하여 망에 의한 셀손실과 셀오류를 정규, 지수함수 분포로 발생시켰으며 비디오 소스는 움직임 특성에 따라 드라마, 스포츠로 나누어 시험한다. 시험결과 주관적 QoS 등급5(Excellent)의 서비스 품질을 만족시키기 위한 망의 CLR 및 CER은 CLR&CER < $2{\times}10^{-7}$ 이었고, 주관적 QoS 등급4(Good)의 서비스 품질을 만족시키기 위한 망의 CLR 및 CER은 CLR&CER < $2{\times}10^{-6}$ 이었다. 본 연구결과는 ATM 망을 이용한 MPEG-2 화상 서비스 제공시 사용자가 요구하는 서비스 품질을 만족시키기 위한 망의 성능 목표치를 결정하고 망을 설계하는데 유용한 자료로서 활용할 수 있다. When providing MPEG-2 video service through the ATM network, the degradation of QoS caused by cell losses and cell errors occuring from ATM netwok was assessed by the end-users subjectively and then the relation between CLR, CER and subjective QoS of MPEG-2 video was analyzed. Cell losses and cell errors occuring from the ATM network were generated according to the normal and exponential distribution by NEM module. Video sources were divided into sports and drama by moving feature and were tested. The results of our experiments show that the excellent quality of subjective QoS grade 5 was achieved for a cell loss rate of $2{\times}10^{-7}$ and for a cell error rate of $2{\times}10^{-7}$ and the good quality of subjective QoS grade 4 was achieved for a cell loss rate of $2{\times}10^{-6}$ and for a cell error rate of $2{\times}10^{-6}$ When providing MPEC-2 video service through the ATM network, the results of our experiments will be used as valuable information to determine the network performance objectives for satisfying the QoS required by the end-users and to design the network.

B-ISDN용 광위성 통신 업링크의 앙각에 따른 송신안테나 최적설계에 관한 연구

한종석,이준구,정진호,김영권 대한전자공학회 1995 전자공학회논문지-A Vol.32 No.10

In this paper, atmospheric turbulence and absorption under clear weather condition, which affect the optical satellite up-link communication between geo-satellites and earth station, were studied. In case of the up-link communication, the received optical power is weakened by pointing loss caused by beam tilt which is the main effect of turbulent atmosphere. This pointing loss directly has relation to the diameter of optical transmitting antenna. From the inverse proportion of the pointing and spaced loss, it is the regions where the diameter of transmitting antenna increases abruptly and the efficient design of transmitting antenna is impossible. In case of using channel coding, it was shown that the peak value of diameter moved to the lower regions of elevation angle with increasing the coding gain and its width was also decreased. In case of considering both coding gain and transmission rate on the design of transmitting antenna, it was known that more coding gain was necessary as transmission rate was increased.

고체윤활제로서의 탄소나노소재 및 응용

한종석,현유라,박현호,이창섭,Han, Jong-Seok,Hyeon, Yu-Ra,Park, Hyeon-Ho,Lee, Chang-Seop 한국고무학회 2020 고무기술 Vol.21 No.2

감성돔, Acanthopagrus schlegeli의 종묘생산 및 성분화에 미치는 영향

한종석,김용구,라성주,윤호섭,이원교,김정,최상덕 國立 麗水大學校 環境問題硏究所 2002 環境硏究論文集 Vol.5 No.-

This study was carried out to produce the seeding of the larvae and juvenile of black sea bream, Acanthopagrus schlegeli in terms of artificial hatching, feeding behavior and growth rate in each factor. Total length of black sea bream larvae hatched was 2.57±0.35mm and after 50 days, total length was 22.08±3.74mm, 49.7% in survival rate. This research was conduced to confirm the effect of tributyltin and 2,4-dinitrophenol on the sex differentiation in Black Sea bream, Acanthopagrus schlegeli. Fish were reared of oral administration of tributyltin at 0.05, 0.5, 5㎍/g and 2,4-dinitrophenol at nominak concentration of 0.05, 0.5, 5, 50㎍/g diet from 156 days to 185 days after hatching. In the process of the differentiation until 156 days after hatching, gonads were composed testis. In contrast, 185 days after hatching, testis were composed of a number of spermatogonia and sperm duct. The female in the control in which sex differentiation of Acanthopagrus schlegeil was normally conducted was 100%. The experimental unit of estradiol-17β, it was 100% in 0.05㎍/g diet concentration, which was similar to the sex ratio of the control. And it was 100% in 0.5㎍/g diet concentration. In each experimental unit with 5, 50㎍/g diet concentrations, every individuals of them differentiated to males. About the experimental unit of tributyltin, the females were 100%, 100%, 100%, 100% and 100% in 0.05㎍/g, 0.5,㎍/g, 5㎍/g and 50㎍/g diet concentrations, respectively. About the experimental unit of 2,4-dinitrophenol, the males were 100% tn 0.05, 0.5, 5, 50㎍/g diet concentrations, respectively.