• Composites Research
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• v.36 no.4
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• pp.259-263
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• 2023

This study investigated the open hole tensile (OHT) properties of carbon fiber/epoxy composites and compared them to bolt joint tensile (BJT) properties. The net nominal modulus and strength (1376 MPa) were found to be higher than the gross nominal strength (1041 MPa), likely due to increasing hole size. The OHT and BJT specimens exhibited similar stiffness, as expected without bolt rotation causing secondary bending. OHT specimens experienced a sharp drop in stress indicating unstable crack propagation, delamination, and catastrophic failure. BJT specimens failed through shear out on the bolt side and bearing failure on the nut side, involving fiber kinking, matrix splitting, and delamination, resulting in lower strength compared to OHT specimens. The strength retention of carbon fiber/epoxy composites with open holes was 66%. Delamination initiation at the hole's edge caused a reduction in the stress concentration factor. Filling the hole with a bolt suppressed this relieving mechanism, leading to lower strength in BJT specimens compared to OHT specimens. Bolt joint efficiency was calculated as 15%. The reduction in strength in bolted joints was attributed to fiber-matrix splitting and delamination, aligning with Hart Smith's bolted joint efficiency diagram. These findings contribute to materials selection and structural reliability estimation for carbon fiber/epoxy composites. They highlight the behavior of open hole and bolt joint configurations under tensile loading, providing valuable insights for engineering applications.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.3
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• pp.180-186
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• 1985

Field and phytotron experiments were conducted to determine the effect of morphological growth stage and environmental temperature on Weender components and net energy lactation (NEL) in corn cv. Blizzard and sorghum cv. Pioneer 931 and Sioux at Munich Technical University from 1978 to 1981. Various growth stages of maize and sorghum were grown for 42 days at 4 temperature regimes (30/25, 25/20, 28/18 and 18/8 degree C) and mid-summer sunlight over 13 hour days. The results obtained are summarized as follows: 1. Accumulation of crude protein in maize and sorghum plants was associated with leaf weight ratio and leaf area ratio ($P{\leq}0.1%$). Crude protein in the plants were shown to have a greate synthesis rates at early growth stages. The highest concentration of crude protein were found at 3-leaf stage with 31.4% and 33.9% for maize and sorghum, respectively. 2. Synthesis of crude fiber was increased after growing point differentiation markedly and were shown the highest concentration at heading stage with 28.4% and 31.5% for maize and sorghum, respectively. During the maturities, the crude fiber contents in maize were, however decreased and shown a value of 19.5% at physiological maturity, while that of sorghum were increased continuously. 3. NEL value in maize and sorghum plants were declined as morphological development and shown the lowest at growing point differentiation with 5.82 MJ (maize) and 5.46 MJ/kg (sorghum). During the late maturity, the NEL value of maize were increased markedly and shown a value of 6.70 MJ and 6.94 MJ/kg for milkstage and maturity stage, respectively, while NEL value in sorghum were not increased markedly. 4. Net energy lactation in maize and sorghum plants were associated with synthesis rate of non-structural carbohydrates, especially mono- and disaccharose while cell-wall constituents and crude fiber lowerd NEL contents ($P{\leq}0.1%$). 5. NEL accumulation and starch value were decreased under temperature. The NEL concentration of 4-leaf sorghum under different environmental temperatures of 30/25, 25/20, and 18/8 degree C were 4.87 MJ, 5.46 MJ and 5.81 MJ/kg, respectively.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.559-565
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• 2009

The implementation possibility and increasement of transmission distance of 1 Tbps WDM transmission systems through the applying optical link configuration with inline dispersion management (DM) and optical phase conjugator (OPC) is investigated. When the considered optical link configuration is applied into $26{\times}40$ Gbps WDM transmission system and the optimal net residual dispersions (NRDs) depending on transmission length are decided, the effective transmission distanceis highly increased than that resulted in same system with fixed 0 ps/nm NRD in all transmission length. And, design rule of inline DM optical link is also shown through inducing the effective range of precompensation and postcompensation depending on transmission distance and launching power of WDM channel.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.208-217
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• 2013

The optimal residual dispersion per span (RDPS) slope is induced through the analyses of the compensation characteristics of the wavelength division multiplexed (WDM) channels depending on RDPS slope in the optical links with a dispersion management (DM) and an optical phase conjugation. The simulation results show that the effective launch power of WDM is more increased and the performance difference between the channels is more decreased as RDPS slope is more increased. The simulation results also show that the effective net residual dispersion (NRD) range is more increased as RDPS slope is more increased, and consequently, it is more advantageous to use the large RDPS slope for implementing the flexible optical links.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.749-751
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• 2009

Optical link design technique for compensating of distorted 40 Gbps ${\times}$ 24 channels WDM signals is researched. The considered optical link consists of optical phase conjugator (OPC) placed at 100 km and 900 km, which are non-midway of total transmission distance, and dispersion management (DM). It is confirmed that optimal net residual dispersions (NRD) are 800 ps/nm and 900 ps/nm when OPC placed at 100 km and 900 km, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.4
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• pp.346-351
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• 1997

The pin bearing strength is one of the most important design parameters for mechanical joints composed of fiber reinforced composites. Thus the effect of the edge distance and the width of specimen on the pin-bearing strength of unidirectional CFRP composites were experimentally investigated in this paper. As results, the failure modes and the pin bearing strength of mechanical joints turned out to depend on the edge distance and also the width of specimen. The failure of specimen with low ratio of width to hole diameter was caused by the net tension from the hole boundary, on the other hand, the failure of specimen with low ratio of edge distance to hole diameter was caused by the shear-out. The bearing strength in case of the failure by shear-out was quite lower than that in case of failure by net tension.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.205-208
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• 2002

When establishing the submarine optical fiber table between international and domestic, marine survey in advance it grasps the submarine geological features which is accurate and a depth of water condition. And the route which is safe for selecting and submarine optical fiber cable laying it is a work which secures an ease one location. If also, the PLGR the submarine of optical fiber table root the sea contamination material (rope, wire and net) it removes in advance and if the submarine of the optical fiber cable ease it does to arrive safely. And it is a work the Plough and ROV laying work hour laying work efficiency improvement and laying equipment it will be able to protect. So, This paper presents the monitoring system of ship information management and operation for marine survey and PLGR work in submarine optical fiber table construction enterprise. In order to achieve these purpose, overall serial multi-port communication modulo of configuration, realtime processing for management and operation of receiving data, realtime graph and a printout are described.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.816-821
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• 2017

An integrated slow mixing/sedimentation and net fit fiber filtration system has been developed to reduce the high concentrations of suspended solid (SS) and total phosphorus (T-P) in the reject water from sewage/wastewater. A filtration device used in this experiment consists of coagulation, in-line mixing, air injection, slow mixing/sedimentation, and filtration processes. The performance test using this device was carried out with six operational modes for reject water from sewage treatment plant. Experimental conditions used were 16.7, 33.3, 41.7 and 50.0 ton/day of flow rate and 2~4 of Al/P molar ratio. By injection of coagulant in each operational mode, the high removal efficiencies of SS and T-P were obtained, but continuous operation time was decreased to 7.8~11.4 min in most modes. However, when the Mode 5 of the developed filtration device was applied, the continuous operation time was maintained up to 88.2 min. Also, it was found that the continuous operation time in the Mode 5 using the developed system was increased from 8 to 11.3 times longer than those in other modes. Backwashing flow rate was also very low at 5.4% of total filtered water. Therefore, it can be concluded that the Mode 5 of the developed filtration system was the most efficient treatment method for the removal of high concentrations of SS and T-P.

• Information and Communications Magazine
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• v.14 no.5
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• pp.128-146
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• 1997

정보통신서비스의 멀티미디어화, 실시간화가 보편적 요구조건으로 자리잡으면서 인프라의 광대역화, 고속화가 당면 과제로 되고 있다. 현존하는 가입자망이 집선 혹은 다중화 기능을 이용한 페어게인 시스템을 기반으로 하고 있으나, 규제완화와 정보통신서비스 고도화에 의해 새로운 가입자망의 탄생이 예고되고 있다. 이에 따라 기존 동선을 사용하여 전송 대역을 확장하는 xDSL(x Digital Subscriber Line)기술, 광케이블을 사용하여 광대역 전송능력을 지원할 뿐 아니라 가입자 배선능력을 획기적으로 개선하는 FTTx(Fiber To The x)기술, 광대역 전송 능력을 지원하는 광휘더와 배선 순기비용을 원천적으로 삭감시키는 무선 배선을 결합하여 새로운 비지니스 기회를 제공하는 HFR(Hybrid Fiber Radio)기술, 댁내 배선상의 병목을 제거하기 위한 WHAN(Wireless Home Area NetWork) 기술등이 가입자 접속능력을 초고속화하기 위한 기반이 될 것으로 예상된다. 본고에서는 정보통신서비스의 발전이 가입자 접속방식과 가입자망의 구성방식에 미치는 영향을 분석하고, 초고속 가입자 접속 기술의 전개 방향과 가입자망의 진화 전망을 기술한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.625-626
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• 2015

The optimal distribution pattern for the compensation for the distorted WDM signals due to the group velocity dispersion (GVD) and the nonlinear Kerr effects is induced in $80km{\times}50spans$ optical link with an artificial distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS).