• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.9-20
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• 2008

It is important to increase the economy and efficiency of the diaphragm of the steel box girder bridge design. In this study, an experimental test is performed in a 4-span steel box girder bridge, which was under constructed according to the dead load of slab concrete and vehicle load. The test result is analyzed to verify the stress distribution of the diaphragm and the middle span. Next, stresses on the vertical stiffener are analyzed according to height. Stresses on the diaphragm with equal height are arranged respectively. Also, the stress distribution of the diaphragm and the middle span. Next, stress on the vertical stiffeners are analyzed according to height. Stresses on the diaphragm with equal height are arranged respectively. Also, the vertical stiffeners in the diaphragm was studied, and using the analyzed results, the proper length of the ratio of vehicle load with curing concrete to vehicle load with asphalt is calculated in each part of the steel box girder bridge. The results provide data that serve as basis for an economical and efficient design for the steel box girder bridge diaphragm.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.671-680
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• 2007

In this study, we performed a loading test to evaluate the effect of load distribution on continuous two-span plate-girder bridges with or without bottom lateral bracing using one-fifth-scale bridge specimens. From the test results, when specimens with lateral bracing were loaded eccentrically, the load distribution capacity of the concrete deck and cross beam improved and greater loading was distributed to the other side of the girder subjected to loading. The load distribution rate of the specimens with and without lateral bracing system was evaluated from the analytical model that was verified by the test results. From the result of the quantitative evaluation, when specimen without lateral bracing was loaded eccentrically, mostly 21% of loading according to the concrete deck was distributed to the other side of the girder subjected to loading. However, when specimen with lateral bracing was loaded eccentrically, the load distribution rate increased by 1.7 times as all cross beams, bracing and concrete deck participated in load distribution. The reason is that the torsional rigidity increased as the model with lateral bracing behaved like a pseudo-closed box section.

• Journal of Aquaculture
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• v.15 no.3
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• pp.139-143
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• 2002

Saringosterols have been isolated from the sponge Penares incrustans. The structure of these compounds have been determined by extensive 2-D NMR experiments such as $ ^1 H$ COSY, HMQC, and HMBC and by comparison with published data. Assignment for carbons of saringosterols for the first time has been done.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.253-256
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• 2003

현재 IETF RFC 3414에서 제안한 SNMP 메시지 인증 및 기밀성 서비스용 키 분배방식은 관리자의 패스워드를 기반으로 국지 키를 생성하는 알고리즘을 사용한다. 이는 관리자의 패스워드 노출 방지를 위해 관리자가 지리적으로 분산된 SNMP 관리객체 (Managed Agent)를 순회하면서 설치해야 한다는 문제점과 또한 관리객체에 SNMP 메시지를 전송되는 시점에서 국지 키가 계산되어 SNMP 메시지의 전송지연 문제점을 내포하고 있다. 본 논문에서는 누구나 관리객체 설치가 가능하고 SNMP 메시지 전송지연을 제거할 수 있도록 SNMPv3 USM에 Diffie-Hellman 키 분배 방식을 적용하는 방안을 제안하였다. 제안된 방식은 RFC 3414와 동일한 수준에서 SNMP 메시지 인증 및 기밀성 서비스를 제공한다.

• KSBB Journal
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• v.20 no.4
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• pp.253-259
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• 2005

This study was accomplished using attached $A^2/O$ process that contains nonsurface-modified and surface-modified polyethylene media inside the Anaerobic/Anoxic, Oxic tank, respectively. We could make the hydrophobic polyethylene media have hydrophilic characteristics by radiating ion beam on the surface of the media. The objectives of this study is to investigate the removal efficiencies of the organics and nitrogen when the step feed ratio of raw wastewater into anaerobic and anoxic tank is changed. In this case, we assumed that the denitrification rate can be improved because the nitrifiers in anoxic tank can perform denitrification using RBDCOD instead of artificial carbon sources (for example, methanol, etc.). The wastewater injection rate into anaerobic/anoxic tank was set up by the ratio of 10 : 0, 9 : 1, 8 : 2, 6 : 4, and the results of BOD removal efficiency showed similar trends with $93.3\%,\;92.6\%,\;92.4\%\;and\;91.6\%$, respectively. But the BOD removal efficiency (utilization of the organics) in the anoxic tank was in the order of 9 : 1 $(84.8\%)$, 10 : 0 $(77.0\%)$, 8 : 2 $(75.3\%)$, and 6 : 4 $(61.1\%)$. The T-N removal efficiency was most high when the ratio is 9 : 1 $(67.4\%)$, and other conditions, 10 : 0, 8 : 2, 6 : 4, showed $61.3(\%),\;60.7\%,\;55.5\%$, respectively; the ratio 6 : 4 was found to be lowest T-N removal efficiency, lower than the ratio 9 : 1 by $12\%$. Though the nitrification rate of the ratio 10 : 0, 9 : 1, and 8 : 2 showed similar levels, the ratio 6 : 4 showed considerable inhibition of nitrification, ammonia was the great portion of the effluent T-N. The advantages of this process is that this process is cost-saving, and non-toxic methods than injecting the artificial carbon source.

• Journal of Energy Engineering
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• v.9 no.4
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• pp.366-371
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• 2000

본 연구는 동적형 빙축열시스템에 있어서 증발판이 축열조 상부에 설치되어 생성된 얼음을 주기적으로 분리, 이탈시켜 하부에 설치된 축열조에 저장하는 기존의 하베스트형 빙축열시스템과는 반대로 축열조 내에 증발판을 설치하여 수중에서 얼음을 생성시키고 분리시켜 부럭에 의해 얼음을 띄워 저장하는 새로운 방식의 수중 하베스트형 빙축열시스템 개발에 관한 연구이다. 본 방식은 축열조 내에 증발판이 설치되어 제빙과 탈빙이 이루어짐으로서 기존 시스템에 설치되는 순환펌프나 순환수 분배기 및 배관 등의 설비가 불필요하고, 또한 조내 물과 증발판이 직접접촉에 의해 열교환이 이루어지므로 기존 공기 중에서의 열교환 방식보다 전열효율이 우수한 장점을 가지고 있다. 따라서 본 연구에서는 상기의 수중 빙제조 방식에있어 빙 제조시와 방냉시 축열조의 열특성을 실험적으로 밝혀 시스템 최적화 및 성능 향상에 대한 기초 자료를 제공하고자 하였다.

• Journal of environmental and Sanitary engineering
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• v.24 no.1
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• pp.13-24
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• 2009

This study was performed to determine the effect of the influent flow distribution ratio and hydraulic retention time(HRT) on removal of organic matter, nitrogen and phosphorus when domestic sewage was treated by the advanced step aeration(ASA) process. Results of the experiment for the determination of the optimum influent flow distribution ratio between the anaerobic reactor and the anoxic reactor showed BOD removal efficiencies of above 92.0% at all influent flow distribution ratios from 9:1 to 4:6. The highest T-N removal efficiency was 82.6% at the influent flow distribution ratio of 6:4. On the other hand, the highest T-P removal efficiency was 67.8% at the influent flow distribution ratio of 9:1. Considering both the T-N and T-P removal efficiencies, the influent distribution ratio of 6:4 was considered the optimum. Results of the experiment for the determination of the optimum HRT at the optimum influent flow distribution ratio of 6:4 revealed BOD removal efficiencies better than 92.7% at all HRTs from 12hr down to 6hr. The highest T-N and T-P removal efficiency were 82.6% and 59.5%, respectively both at the HRT of 8hr. In conclusion, the optimum influent flow distribution ratio and HRT for treatment of domestic sewage by the ASA process were determined to be 6:4 and 8hr, respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.105-112
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• 2010

Recently, wireless communication systems have been developed and the circuits which operate with the broad-band for multiband uses were introduced. However, broad-band circuits have problems that inevitably increase the size. Dual-band circuit operates only two frequency, therefore, it will be able to miniaturize through unnecessary decreased elements. The Wilkinson power divider is the one of the most commonly used components in wireless communication system for power division. Nowaday, the Wilkinson power divider is also demanded dual-band. In this paper, I propose miniaturized dual-band Wilkinson power divider operating at 2.45 GHz and 5.2 GHz for IEEE 802.11n standard. Proposed dual-band Wilkinson power divider is used in parallel stub line. The design is accomplished by transforming the electrical length and impedance of the quarter wave sections of the conventional Wilkinson power divider into dual band ${\pi}$-shaped sections.

• JOURNAL OF ELECTRICAL WORLD
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• no.7 s.31
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• pp.72-78
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• 1979

전기사업은 국가산업발전의 열쇠이다. 우리와 가까운 이웃나라들에서는 어떻게 전기를 생산하며 어떻게 분배하며 또 무엇이 우리가 배울 점인가를 알아야만, 우리의 전기사업도 보다 발전할 수 있을 것이다. 금번호부터 일본해외전력조사회에서 발간한 ${\ulcorner}$아세아 전기사업${\lrcorner}$에서 아시아 각국의 전기사업에 관한 기사를 발췌하여 싣는다.

• JOURNAL OF ELECTRICAL WORLD
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• no.8 s.32
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• pp.49-54
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• 1979

전기사업은 국가산업발전의 열쇠이다. 우리와 가까운 이웃나라들에서는 어떻게 전기를 생산하며 어떻게 분배하며 또 무엇이 우리가 배울 점인가를 알아야만, 우리의 전기사업도 보다 발전할 수 있을 것이다. 금번호에는 일본해외전력조사회에서 발간한 ${\ulcorner}$아세아 전기사업${\lrcorner}$에서 말레이시아의 전기사업에 관한 기사를 발췌하여 싣는다.