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전자 제어식 가솔린 엔진의 벽류 생성 요인에 관한 연구
김봉규,이기형,이창식,Kim, Bong-Gyu,Lee, Ki-Hyung,Lee, Chang-Sik 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.11
Mixture formation is one of the significant factors to improve combustion performance of an spark ignition engine. This is affected by spray and atomization characteristics of injector. In the case of EGI system, air-fuel mixing period is so short that a lot of fuel-film and liquid-fuel flow into cylinder. Since this fuel-film is not burnt perfectly in cylinder, it is exhausted in the form of HC emission. In this paper, three measurement techniques were utilized to measure spray characteristics and the amount of fuel-film in the cylinder. At first, PMAS was used to measure the spray characteristics such as size distributions, SMD, and spray angle. Secondly the amount and distribution of fuel-film which flow into through intake valve could be measured quantitatively using the fuel-film measuring device. And lastly, by optical fiber type spark plug used to detect the diffusion flame, the amount of unburned HC was measured. As the result of these experiments, the information of optimal spray characteristics and injection condition to minimize fuel-film could be built up.
김봉규,노덕규,Kim, Bong-Gyu,No, Deok-Gyu 한국천문학회 1992 天文學論叢 Vol.7 No.1
We observed a total of 14 Mira variables as well as 4 late type variable stars for their SiO ${\nu}= 1$, J = 2 - 1 maser lines from April 1989 to November 1990 with the 13.7 m radio telescope at Daeduk Radio Astronomy Observatory. The maser intensity variations were the prime objective of the observations which well covered the periods of the variations. The origion of the variations were studied by comparing wi th those previousely measured in optical and infrared(IR) wavelengths and we confirmed that the intensity variations were in good correlation with those in V magnitude and IR intensity as previousely found in former investigators in general. However, for a few sources, we could find the missing maxima. The intensities themselves also were in good correlation with SiO ${\nu}\;=\;1$, J = 1 - 0 maser intensities observed in Yebes as expected. The good correlations indicate that the pumping source of the SiO maser is likely to be the IR emission in the masing regions and the "missing maxima" that are apparent in two particular sources are considered to relate wi th the strength of shocks arising from the eruptive mass-loss from central stars.
정적 대변형에 중첩된 미소 동적 하중을 받는 고무재료의 점탄성 구성방식에 관한 연구
김봉규,윤성기,Kim, Bong-Gyu,Yun, Seong-Gi 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.4
A viscoelastic constitutive equation of rubber is proposed under small oscillatory load superimposed on large static deformation. The proposed model is derived through linearization of Simos nonlinear viscoelastic constitutive model and reference configuration transformation. Statically pre-deformed state is used as reference configuration. The model is extended to a generalized viscoelastic constitutive equation including widely-used Mormans model. Static deformation correction factor is introduced to consider the influence of pre-strain on the relaxation function. The model is tested for dynamic behavior of rubbers with different carbon black fractions. It is shown that the constitutive equation with static deformation correction factor agrees well with test results.
김봉규,정재훈,Kim, Bong-Gyu,Jeong, Jae-Hun 한국천문학회 1992 天文學論叢 Vol.7 No.1
We determined the efficiencies of the aperture. beam and forward spillover and scattering of 13.7 m radio telescope at Daeduk Radio Astronomy Observatory through the observations of the planets and Moon. The main panels adjustments were carried out on September 1991 and the improvements in the efficiencies were checked by comparing the observations made before and after the panel adjustments. The efficiencies were turned out to be 0.35, 0,47 and 0.83 at 115.27 GHz for the aperture, beam and forward scattering and spillover. respectively. These marked nearly a factor of two upgrade of the efficiencies previously measured.
IEEE 802.11s MCCA 의 성능 향상을 위한 RSRR 스케쥴링 알고리즘 설계 및 성능 분석
김봉규(Bong Gyu Kim),정회진(Whoi Jin Jung),이재용(Jae Yong Lee),김병철(Byung Chul Kim) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.3
무선 메쉬 네트워크의 표준인 IEEE 802.11s의 매체 접근 방식은 IEEE 802.11e에서 사용되던 EDCA를 기본으로 사용하고, 옵션으로 MCCA를 사용한다. EDCA는 각 트래픽을 네 개의 AC 로 구분하여 차별화된 서비스를 제공하는 기술이고, MCCA는 TDMA 기반의 기술로서 무선 메쉬 라우터 간에 무선 채널의 슬롯을 예약하여 플로우의 대역폭을 보장하는 방식이다. 그러나 MCCA는 이웃 노드와의 대역폭 예약을 통하여 각 플로우들의 요구대역폭과 공정성을 보장할 수는 있지만, 플로우가 멀티미디어 응용의 VBR 트래픽인 경우 예약된 대역폭을 모두 사용하지 못 하고 낭비되는 단점이 있다. 이에 본 논문에서는 MCCA를 사용하는 경우 대역폭이 낭비되는 문제점을 제시하고 이를 효율적으로 개선하여 네트워크 활용도를 높이는 알고리즘인 RSRR (Resource Sharing Round Robin) 스케쥴링을 제안한다. 제안된 알고리즘의 성능을 분석하기 위하여 NS-2 시뮬레이션을 통하여 기존의 MCCA에서 낭비되던 자원을 효과적으로 사용하여 네트워크 활용도가 향상됨을 보였다. As a standard of WMNs, IEEE 802.11s supports two kinds of MAC algorithm: a mandatory EDCA used by IEEE 802.11e and an optional MCCA. While EDCA classifies traffic according to four Access Categories (AC) and offer differentiated service using a classified priority, MCCA can guarantee the specific bandwidth of users with a TDMA-style bandwidth reservation scheme between mesh routers. In case that a flow is VBR traffic of a multimedia application, MCCA has disadvantage that the reserved bandwidth does not be used entirely, though it guarantees required bandwidth of users and fairness using bandwidth reservation with neighbors’ node. In this paper, we showed a problem that is wastes the reserved bandwidth when MCCA is enabled and proposed a new scheduling algorithm to prevent waste of bandwidth and to improve network utilization effectively, named Resource Sharing Round Robin (RSRR) scheduling. Finally we showed simulation results that performance of a proposed RSRR is better than the legacy MCCA through NS-2 simulation.