• KOREAN POULTRY JOURNAL
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• v.34 no.6 s.392
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• pp.74-77
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• 2002

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.99-111
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• 2008

In recent years, the needs for WLANs(Wireless Local Area Networks) technology which can access to Internet anywhere have been dramatically increased particularly in SOHO(Small Office Home Office) and Hot Spot. However, unlike wired networks, there are some unique characteristics of wireless networks. These characteristics include the burst packet losses due to unreliable wireless channel. Note that burst packet losses, which occur when the distance between the wireless station and the AP(Access Point) increase or when obstacles move temporarily between the station and AP, are very frequent in 802.11 networks. Conversely, due to burst packet losses, the performance of 802.11 networks are not always as sufficient as the current application require, particularly when they use TCP at the transport layer. The high packet loss rate over wireless links can trigger unnecessary execution of TCP congestion control algorithm, resulting in performance degradation. In order to overcome the limitations of WLANs environment, MAC-layer LDA(Loss Differentiation Algorithm)has been proposed. MAC-layer LDA prevents TCP's timeout by increasing CRD(Consecutive Retry Duration) higher than burst packet loss duration. However, in the wireless channel with high packet loss rate, MAC-layer LDA does not work well because of two reason: (a) If the CRD is lower than burst packet loss duration due to the limited increase of retry limit, end-to-end performance is degraded. (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily by Reducing the drainage speed of the network buffer due to the increase of CRD. In this paper, we propose a new retransmission module based on Cross-layer approach, called BLD(Burst Loss Detection) module, to solve the limitation of previous link layer retransmission schemes. BLD module's algorithm is retransmission mechanism at IEEE 802.11 networks and performs retransmission based on the interaction between retransmission mechanisms of the MAC layer and TCP. From the simulation by using ns-2(Network Simulator), we could see more improved TCP throughput and energy efficiency with the proposed scheme than previous mechanisms.

• Magazine of the Korea Concrete Institute
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• v.2 no.2
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• pp.93-99
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• 1990

The object of this study was to investigate the flexural stress blocks of High Strength Concrete Members under monotonic loading. Such a stress block should be clearly idealized before High Strength Concrete can be used with confidence in Structural Members. The principal test variables were the Compressive Strength of Concrete, the percentage of longitudinal reinforcement and the spacing of confinement reinforcement. The rectangular stress block of the present ACI Building Code was found to give acceptably conservative flexural strength predictions over the entire range of concrete strength from 280kg/crd (4Ksi)to 1050kg/crd( 15Ksi)

• KOREAN POULTRY JOURNAL
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• v.36 no.10 s.420
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• pp.154-155
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• 2004

마이코플라즈마는 양계 산업에 경제적 손실을 임하는 질병중의 하나이다. 그 중에서도 마이코플라즈마 갈리셉티컴(MG, mycoplasma gallisepticum)은 호흡기 질병을 유발하고 산란율을 떨어뜨리며, 마이코플라즈마 시노바에(MS, mycoplasma synoviae)는 호흡기와 관절이상을 가져온다. MG는 MS보다 더 큰 경제적 손실을 입히고 있다. 본 고에서는 MG에 대한 일반 이해와 미국에서의 예방 실태를 알아 본다. MG는 축제를 떠나면 덥고 건조한 조건에서는 불과 몇 시간밖에 생존하지 못하는 유기체이다. MG는 감염 닭과의 직접접촉, 가까운 거리에서는 공기를 통해, 또는 오염된 기구나 작업자들을 통해 수평 감염되거나 종란을 통해 수직감염 된다. MG 감염은 만성호흡기(CRD, Chronic respriatory disease)의 원인이 되는데 특히 어린 병아리와 브로일러에서 그러하다. CRD 즉 만성 호흡기증의 정도는 MG병원성, 전염성 기관지염(IBV, intectious bronchitis virus), 그리고 대장균증과 같은 2차 감염에 의해 더욱 악화 되게 된다.

• KOREAN POULTRY JOURNAL
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• v.9 no.5 s.91
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• pp.52-54
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• 1977

전염성 코라이자는 헤모필러스 갈리나리엄에 의해 일어나는 전염성의 호흡기 병으로 수양성 콧물과 부종성 종장, 눈물을 흘리는 것을 주증으로 해서 이 병 자체보다는 이로 인한 만성 호흡기 병의 유발이 바로 중요한 문제가 된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.373-379
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• 2005

Papers on improvement of electromagnetic field uniformity in a reverberation chamber with 1D Quadratic Residue Diffuser of Schroeder method has been published several times. In this paper, to obtain improved electromagnetic field characteristics and field uniformity in a reverberation chamber, cubical residue diffuser sets of Schroeder type are designed for a chamber in $2.3\;\cal{GHz}\~3\;\cal{GHz}$. The FDTD(Finite-Difference Time-Domain) technique is used to analyze the field characteristics in a chamber. Cubical residue algorithm and 2D arrangement show more randomness than the previous study results. The characteristics of tolerance, polarity, deviations, as well as power efficency, are improved with cubical residue diffuser sets in a chamber.

• Korean Journal of Oriental Medicine
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• v.17 no.3
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• pp.105-114
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• 2011

Objectives : The transient inflammation has been demonstrated to alter visceral motor response (VMR) and acute mucosal inflammation may precede the manifestation of visceral hyperalgesia in animal models. The purpose of our study is to compare effects of the different frequencies applied electroacupuncture (EA) on acupoints in acute colitis induced by trinitrobenzenesulphonic acid (TNBS). Methods : In Male Sprague-Dawley rats, weighing 250~400g, a single colorectal administration of TNBS (5mg/kg) was made and electrode for electromyography (EMG) recording were stitched into the external oblique musculature. EA of either ST25 or ST36 were applied and stimulation parameter was modulated as follows: 2, 10, or 100 Hz with intensity of 2 mA and 1 ms pulse duration for 30 min. The balloon was inserted intra-anally and VMR to colorectal distension (CRD) was quantified with an EMG recording system. Results : The VMR increased significantly 3 days after TNBS intra-rectal colonic injection in rats. Both 2 Hz and 10 Hz EA on ST36 suppressed VMR to CRD in the acute colitis model but not 100 Hz. Only 10 Hz EA on ST25 suppressed VMR to CRD in the acute colitis. Conclusions : These data show that 10 Hz EA potently inhibits hypersensitivity of colorectum after TNBS induced colitis.

• Journal of Chest Surgery
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• v.51 no.6
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• pp.367-375
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• 2018

Background: It is unclear whether mitral valve (MV) repair for degenerative mitral regurgitation (MR) provides the same advantages in the elderly that it does in the general population. Methods: From 1994 to 2016, 188 elderly patients (mean age, $68.3{\pm}5.50years$) underwent MV repair (n=153) or MV replacement (n=35) for primary degenerative MR. Early and long-term outcomes were compared before and after propensity score matching (PSM). Results: Before PSM, there was a significant difference in operative mortality (p=0.011). Overall survival and freedom from cardiac-related death (CRD) at 5, 10, and 15 years were significantly higher in patients who underwent MV repair (p=0.039 and p=0.007, respectively). In the multivariable analysis, MV replacement was an independent risk factor of CRD. After PSM, operative mortality was not significantly lower in patients who underwent MV repair (p=0.125). Overall survival and freedom from CRD at 5, 10, and 15 years showed no significant difference between the 2 groups in the PSM cohort (p=0.207, p=0.47, respectively). There was no significant difference in freedom from reoperation before or after PSM (p=0.963 and p=0.575, respectively). Conclusion: MV repair for primary degenerative MR might be a valid option in the elderly population if successful repair is possible.

• Analytical Science and Technology
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• v.22 no.5
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• pp.376-385
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• 2009

In our study, the accuracy for measurement of seventeen 2,3,7,8-substituted PCDDs/PCDFs in certified reference material (CRM) which is the sample of homogeneous sediment matrix taken from an area known to have significant chemical contamination, particularly PCBs (polychlorinated biphenyls), was evaluated. Though the methodology in this study followed the official method of unintentionally produced persistent organic pollutants (UPOPs) announced by the Ministry of Environment of the Republic of Korea in 2007, there were slight changes using additional purification step by activated carbon column because the interferences of sample were not sufficiently removed when only multi-silica column and alumina column have been used for purification. The |En| number proposed by the Korea Research Institute of Standards and Science was used for a valuation basis of the accuracy. The |En| numbers of seventeen 2,3,7,8-substituted PCDDs/PCDFs have been indicated as 1 and below, they were decided "Pass" in this test, when DB-5MS column and SP-2331 column were used together. Because 1,2,3,7,8-PeCDD and #169-HxCB were not separated on DB-5MS column, the ions of 1,2,3,7,8-PeCDD were selected at M/M+2 instead of M+2/M+4 suggested by EPA 1613. It is possible to distinguish them in HRGC/HRMS analysis.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2029-2035
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• 2013

The impact of phosphorous (P)-doping on the electrochemical performance and surface chemistry of soft carbon is investigated by means of galvanostatic cycling and ex situ X-ray photoelectron spectroscopy (XPS). P-doping plays an important role in storing more Li ions and discernibly improves reversible capacity. However, the discharge capacity retention of P-doped soft carbon electrodes deteriorated at $60^{\circ}C$ compared to non-doped soft carbon. This poor capacity retention could be improved by vinylene carbonate (VC) participating in forming a protective interfacial chemistry on soft carbon. In addition, the effect of P-doping on exothermic thermal reactions of lithiated soft carbon with electrolyte solution is discussed on the basis of differential scanning calorimetry (DSC) results.