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임성빈,조병규 충주대 산업과학기술연구소 1999 産業科學論文集 Vol.7 No.1
The purpose of this study was to design a tool for supporting breakup length. This tool was designed to provides informations as follow: 1) Weber's number computed automatically 2) Reynold's number computed automatically 3) Ohnesorge's number computed automatically 4) theoretical breakup length computed automatically 5) graph compared theoretical breakup length with practical breakup length 6) etc.
다중 경로 채널 환경에서 PPM 기반의 초광대역 무선 통신 시스템의 수신기 구조
김성준,임성빈 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-
In this paper, we propose two receiver structures of the ultra wide-band (UWB) wireless communication system to improve its performance in multipath environments. Recently, the UWB communication system has drawn much attention for future high-speed wireless communication services. The conventional UWB receiver directly correlates received signals with the ideal reference waveform, which results in performance degradation for multipath environments. The key idea of the proposed receiver structure is to reflect the multipath characteristics into the UWB wireless communication system receiver. The first approach is to deconvolve the received waveform with estimates of the multipath gains to obtain the transmitted waveform while the other is to modify the reference waveform of the correlator according to the estimates of the multipath gains. We examined the performance of the proposed schemes for the statistical indoor wireless communication channel model using computer simulation.
핸드오프로 인한 TCP 재전송 타이머의 타임아웃 방지 방안
이상연,임행빈,정충교 강원대학교 정보통신연구소 1999 정보통신논문지 Vol.3 No.-
It will be occurred unacceptably long pause and intermittent disconnection states due to handoffs under the mobile computing environment. The current TCP interprets these handoffs as network congestion and excutes the congestion avoidance algorithms which degrade TCP performance. To prevent degrading TCP troughtput due to the unnecessary timeout problem of source retransmitter timer caused by handoffs, we propose EHN(explicit handoff notification) message algorithm which resets the value of retansmission timer. By adapting EHN, the TCP source can maintain the pre-handoff' congestion window size after handoffs and prevent the abrupt decrease of congestion window size caused by timeout. Therefore, this scheme improves the TCP performance more than the current TCP implementations during handoffs. With the computer simulation, we compare our EHN scheme with the current TCP scheme and fast retransmission scheme and prove the validation of EHN.
다중 경로 채널 환경에서 PPM 방식의 초광대역 무선 통신 시스템의 PRF와 Slot Time의 영향
김성준,임성빈 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-
In this paper, we investigate the effect of pulse repetition frequency (PRF) and slot-time interval on the good-put performance of the ultra wide-band (UWB) wireless communication systme in multipath channels. Recently, due to many desirable features of the UWB system, it has drawn much attention especially for short-range high-speed wireless communication systems. However, there was not much work done for the performance of the UWB wireless communication system in terms of the throughput. Generally, in order to avoid a collision with the next pulse, the condition N_hT_c≤T_f should be satisfied, where T_c and T_f represent the slot interval and frame interval, respectively. The slot interval is one of very important parameters that can control the degree of inter-pulse interference (IPI). In addition, the UWB system can easily control its transmission power by adjusting the PRF. Accordingly, the purpose of this paper is to investigate the effect of varying PRF and slot-time interval on the throughput performance of the UWB system over the time-variant multipath channels.
고속 데이터 패킷 전송을 위한 다중경로 간섭제거기의 성능 비교
김규섭,임성빈 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-
One of problems associated with high-speed data packet transmission systems such as HW-CDMA and 1xEVDO in CDMA2000 is that they show seriously low performance for m channels. The main reason for this is that a high-speed data packet transmission system higher-level modulation schemes such as 8PSK, 16QAM and 64QAM, which have relativel Euclidean distance between symbols. Such schemes are very sensitive to interference and/or no purpose of this paper is to compare the performance and complexity of the multipath inte cancellation algorithms for high-speed data packet transmission. The algorithms considered in are MPIC (Multi-Path Interference Cancellation), SWCE (Sliding-Window Chip Equalizer) and I (Iterative Decision Feedback Equalizer with Hard Decision), which are the existing and propos for minimitigating the effect of multipath interference.
변종철,한성빈,정덕상,임희정,한충훈 濟州大學校 師範大學 科學敎育硏究所 1995 科學敎育 Vol.12 No.1
rac-5.5.7.12.12.14-hexamethy1-1,4,8,11-tetraazacyclotetradecane hydrate : Lm·H_(2)O was prepared and separated from the corresponding meso-isomer dihydrate according to the Curtis method. The racisomer was confirmed by spectroscopic data of NMR and IR spectroscopy. To synthesize the [CrL_m(OH)₂] complex. the racemic compound purified from meso and racemic mixture was reacted with Cr(II1) salt. The complx ion species {[SrL_m(OH)_(2)]^(+): λ_(max) = 613.0(ε_(max) = 116 M^(-1)cm^(-1)), {[CrLm(OH)(H_(2)O)]^(2+) : λ_(max) = 575.0nm(ε_(max) = 133M^(-1)cm^(-1)). [CrLm(H_(2)O)_(2)]^(3+) : λ_(max) = 532.0nm (ε_(max) = 172M^(-1)cm^(-1))} obtained from pH change of [CrLm(OH)_(2)(OH)_(3)]^(+) solution were confirmed from an electron absorption spectra. The result of the distribution diagram of chemical species proves that main products in the range of solution pH ≤ 3.5 . 3.5 <pH <7, and pH ≥ 7. are [CrLm(H_(2)O)_(2)]^(3+). [CrL_(m)(OH) (H_(2)O)^(2+). and [CrL_m(OH)_(2), respectively. At P~ 2.0, we synthesized several Cr(III)-macrocyclic complexes containing various axial ligands (L_(a) : I, Br^(-), CI^(-), S_(2)O_(3)^(2-), F^(-), malonate, NCS^-, oxalate) instead of H_(2)O. [CrL_m(OH_(2))]^(3+) + L_(a) →[CrL_(m)(L_(a))_(n)]^(+)(n = 1 or 2) Cr(III)-macrocyclic complexes combined with vaious ligands on the axial position were primarily confirmed with the mass spectrum. Especially, when the axial ligands are malonate, oxalate, and S_(2)O_(3)^(2-), a possible thermal decomposition reaction and redox potential are considered as follows: ◁표삽입▷(본문을 참조하세요) As well, a spectrochemical series was drawn up on the basis of the ligand field strength obtained from electron absorption spertra of the complexes, [CrL_(m)(La)_(n)]^(p+) F^(-), CI^(-) ~Br^(-)<I^(-)<S_(2)O_(3)^(2-)<OH^(-)<H_(2)O<mal~NCS^(-) We can expect that there is three d-d transition d^(3) ion Tanabe-Sugano diagram. ◁표삽입▷(본문을 참조하세요) However, we found only two trasitions because the other transition {^(4)A_(2)_g(F)→^(4)T_lg(P) : v_(3)} is obscured by absorption arising from charge transfer transition. ◁표삽입▷(본문을 참조하세요)
Design Consideration of Back-EMF Constant for 3-D.O.F. Spherical PM Motor
Sung-chul Go,Dong-woo Kang,Jong-bin Im,Ju Lee,Sung-hong Won,Seung-Bin Lim 한국자기학회 2010 Journal of Magnetics Vol.15 No.2
A 3-D.O.F. spherical PM motor has 3 degrees of freedom in its motion by tilting and rotating of a shaft, which can be applied in a range of fields. The back-EMF is proportional to the field flux and angular velocity. The back-EMF constant in conventional rotating machine has a uniform value. However, in a spherical PM motor, the back-EMF constant of the coils varies according to the tilting conditions regardless of whether the angular speed is constant. Consideration of the back-EMF constant is useful for designing 3-D.O.F. spherical PM motors. In this study, the back-EMF constant of the spherical PM motor was considered carefully.