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이종 재질 디스크 브레이크 로터 마찰면 가공 형태에 따른 성능 변화 연구
홍윤화(Yunhwa Hong),정택수(Taeksu Jung),김청민(Cheongmin Kim),홍영훈(Younghoon Hong),조종두(Chongdu Cho) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.5
In recent years, the automobile industry has been in need of weight reduction for improved fuel efficiency of vehicles. In connection with this, the two-piece disk brake, which is comprised of a lightweight material hat and a cast gray iron rotor, has been developed and commercialized for reduced disk brake weight applicable to high-performance vehicles. Also, the cross-drilled hole and slot, which are machined on the frictional surface of the brake rotor, are generally employed on high-performance brake systems as a method to improve the performance of cooling and gas ventilation as well for aesthetic value. In this paper, the performance of one-piece disk brakes and two-piece disk brakes, which have a drilled hole pattern or slotted pattern on the rotor friction surface, is evaluated and compared. The evaluation is performed by means of a lab dynamometer, and braking performance data such as braking temperature, friction coefficient, and braking torque were gathered. The results have been compared to understand the effect of the machined pattern integrated with the characteristics of the two-piece disk brake.
Younghoon Kwon(권영훈),Gyeongrae Im(임경래),Jae Hong Lee(이재홍) 한국방송·미디어공학회 2016 방송공학회논문지 Vol.21 No.1
This paper analyzes the outage performance of a two-way relay network in the presence of interference from multiple interferers. We investigate a two-way relay network where a single user communicates with a selected other user via a relay during three phases. We propose a user selection scheme and analyze an outage probability. Numerical results verify our analysis by comparison with computer simulation and show effects of the number of users and the number of interferers on its the outage probability.
Effects of coupled bichromatic atom-cavity interaction in the cavity-QED microlaser
Hong, Hyun-Gue,Seo, Wontaek,Lee, Moonjoo,Song, Younghoon,Choi, Wonshik,Fang-Yen, Christopher,Dasari, Ramachandra R.,Feld, Michael S.,Lee, Jai-Hyung,An, Kyungwon American Physical Society 2009 Physical review. A. Atomic, molecular, and optical Vol.79 No.3
Hong, Hyun-Gue,Seo, Wontaek,Lee, Moonjoo,Song, Younghoon,Chough, Young-Tak,Lee, Jai-Hyung,An, Kyungwon The Optical Society 2009 Optics express Vol.17 No.18
<P>This paper describes a novel atom-cavity interaction induced by periodically poled atom-cavity coupling constant which leads to multiple narrow photoemission bands for an initially inverted two-level atom under the strong coupling condition. The emission bandpass narrowing has a close analogy with the folded Solc filter in the context of quasi-phase matching by periodic poling. We present a closed form solution of the emission probability at the end of interaction and deduce the multiple phase matching condition for this system which is programmable by the interaction time. The Bloch sphere analysis provides a clear understanding of the underlying atomic dynamics associated with the multiple resonances in the semiclassical limit. Furthermore, we show that this interaction can be applied to generation of nonclassical fields with sub-Poisson photon statistics.</P>
이종망 환경에서 오버헤드 감소와 수율 향상을 위한 자율적인 펨토셀 전송 전력 조절 기법
조영훈(Younghoon Jo),임재찬(Jaechan Lim),홍대형(Daehyoung Hong) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.1B
저전력, 저가의 초소형 기지국인 펨토셀은 heterogeneous network 의 중요 구성 요소 중 하나이다. 그러나 펨토셀 설치에 따른 셀 구조의 변화는 셀 간 간섭과 signaling overhead 증가와 같은 기술적인 문제를 야기할 수 있다. 이와 같은 기술적인 문제의 해결 방법 중 하나는 펨토셀이 SON(Self-Organized Network)과 같은 기법을 이용하여 자율적으로 전송전력을 조절하는 것이다. 펨토셀은 전송전력 조절을 통해 시스템 throughput을 향상시키거나 overhead를 감소시킬 수 있다. 일반적으로 시스템 throughput을 최대화하기 위한 펨토셀 전송 전력과 시스템 overhead 감소를 위한 펨토셀 전송 전력은 일치하지 않는다. 따라서 본 연구에서는 펨토셀이 시스템 overhead를 감소시키는 동시에 시스템 throughput을 향상시키도록 전송 전력을 조절하는 방법을 제안한다. 모의실험을 통해 제안 기법이 throughput만을 최대화하는 기법에 비하여 시스템 overhead를 41% 감소시키는 것을 확인하였다. 또한 커버리지만을 최적화 하는 기법에 비하여 throughput이 63% 향상되는 것을 확인하였다. Femto-cells are low power/cost, micro-base stations and are main components in heterogeneous networks. However, some of technical issues arise when femto-cells are initially installed. One approach to resolve the problems is to control the transmission (TX) power autonomously via SON(Self-Organized Network) scheme. By controlling the femto-cell TX power, the system throughput performance can be improved or the system overhead is highly reduced. Generally, the TX power for maximizing the system throughput and that for reduced system overhead may not be identical. Therefore, we propose a TX power control scheme by which we can improve the system throughput and reduce the system overhead, simultaneously. When we apply the proposed method, the simulation results show that the system overhead can be reduced by up to 41% compared to the performance of the method which maximizes throughput performance only, and the throughput performance can be improved by up to 63% compared to that of the method which only optimizes the coverage area.
Kim, Younghoon,Koo, Jaehyoung,Hwang, In-Chul,Mukhopadhyay, Rahul Dev,Hong, Soonsang,Yoo, Jejoong,Dar, Ajaz Ahmad,Kim, Ikjin,Moon, Dohyun,Shin, Tae Joo,Ko, Young Ho,Kim, Kimoon American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.44
<P>We report a new approach to building hierarchical superstructures using a shape-persistent porous organic cage, which acts as a premade secondary building unit, and coordination chemistry. To illustrate the principle, a zinc-metalated porphyrin box (<B>Zn-PB</B>), a corner-truncated cubic porous cage, was connected by suitable dipyridyl terminated bridging ligands to construct <B>PB</B>-based hierarchical superstructures (<B>PSS</B>s). The <B>PSS</B>s were stabilized not only by the coordination bonds between Zn ions and bipyridyl-terminated ligands but also by π-π interactions between the corners of the <B>Zn-PB</B> units. By varying the length of the linker, we identified an optimum range of the linker length for construction of <B>PSS</B>s. The <B>PSS</B>s have large void volumes and an extrinsic surface area compared to the parent PBs, which can be exploited for the selective encapsulation and interior functionalization of the <B>PSS</B>s for various applications, including catalysis. We observed that singlet oxygen induced synthesis of the natural product, juglone, is more efficiently catalyzed by <B>PSS-1</B> than its constituent component <B>Zn-PB</B>.</P> [FIG OMISSION]</BR>
정영훈(Younghoon Jung),홍정표(Jung-Pyo Hong) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.4
Development trends of electric motors including automotive applications are focusing at high-precision, high-efficiency, highperformance, small size, and light weight. In all electric machines, temperature rise has a main role in limitation of size and performance. The temperature rise changes the material characteristics used in the electric machines to deteriorate the performance and affect machine size. High performance, high-efficiency, and size reduction of the electric machines can be achieved by reduction of heat source. High-grade permanent magnet, rare-earth permanent magnet, and low-loss electric steel is able to reduce the heat source. This paper shows the influence of magnetic materials on the electric motors and the characteristics of the magnetic material required in electric motors.
Soonsang Hong,Younghoon Kim,Yelin Kim,Kyungwon Suh,Minyoung Yoon,Kimoon Kim 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.2
We report the synthesis and characterization of hierarchical porous carbons (HPCs) prepared by direct carbonization of zinc-based metal?organic frameworks (MOFs), and their electrochemical performance as an electrode material for supercapacitors. All the HPCs showed high porosity (Brunauer?Emmett?Teller (BET) surface areas 1000?1820?m2/g) with micro-, meso-, and macropores. The HPC-based electrodes exhibited a high-specific capacitance in the range of 164?203?F/g (scan rate: 10 mV/s), which suggests that these porous carbons may be useful for fabricating supercapacitors. Among the HPCs, HPC-4 with the largest surface area as well as with ~1% nitrogen content exhibited the highest specific capacitance, which is comparable with those of other reported carbon materials. This work suggests that the hierarchical porosity and nitrogen doping in HPCs may enhance their conductivity and specific capacitance.
홍은표(EunPyo Hong),류승수(SeungSoo Ryu),조한신(HanShin Cho),박완수(WanSu Park),최석규(SeokGyu Choi),지형훈(YoungHoon Ji) 한국자동차공학회 2023 한국자동차공학회 학술대회 및 전시회 Vol.2023 No.11
As automotive industry advance quickly, the most important key-word of future automobile is ‘Personalization’. The air conditioning system also needs to shift away from familiarity and into a new paradigm to apply an efficient indirect ventilation system. To satisfy needs of customer and respond autonomous car, we propose diffusible ventilation system for door trim. In this paper we suggest solution to overcome problems of direct type air conditioning system and limited package of EV platform. In order to implement this technology, we present blower type that have separate intake devices so that they can be applied to various vehicle types. Also we set five major performance factors and set goals through the analysis of air transfer logic. We conducted a preliminary analysis and evaluated the samples based on the analysis results. Through this, various problems were identified and improvement plans were established. After evaluating the final products, it was confirmed that all five major performance factors were satistied. We also establish technical guide about important design factors for general reference. This approach allow our company to be First-Mover from Fast-Follower.