• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.17-25
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• 2005

The dealuminated and alkali/alkaline-earth metal exchanged Y-zeolites were prepared as a catalyst. Elemental compositions and structures of the prepared catalysts were analyzed by the various spectroscopic techniques such as inductively coupled plasma-atomic emission spectroscopy(ICP-AES), X-ray fluorescence(XRF) and X-ray diffraction(XRD), and the desorption behaviors of adsorbed species on the catalyst surfaces were investigated via NO-TPD experiment. Comparing with the composition of the starting material of NaY zeolite, the magnitudes of Si/Al ratio in catalytic materials were increased after dealumination. The Si/Al ratio of catalytic materials after dealumination followed by Cs and Ba cation exchange were additionally decreased. Dealumination to catalysts induced a destruction of basic frame due to a detachment of aluminum, which results in reducing framework structure, while increasing non-framework structure. This phenomenon becomes more serious with increasing time of steam treatment and even more significant for the cation exchanged catalysts. In NO-TPD experiments, the desorption peaks of NO which indicates an activity point of catalysts shifted to the low temperature region after dealumination and cation exchange. The desorption peaks of the NO-TPD profiles taken after steam treatment also shifted to the low temperature region as the steam treatment time increased. In dealuminated and cation exchanged Y-zeolites, the catalytic activities were more influenced by exchanged cation and the formation of non-framework structure.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.181-188
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• 2013

The effect of transition metal ion exchange into UZM-9 zeolite with LTA framework on its deactivation in methanol-to-olefin (MTO) conversion was discussed. The ion exchange of copper, cobalt, nickel, and iron did not induce any notable change in the crystallinity, crystal morphology, and acidity of UZM-9. The small cage entrance of UZM-9 caused the high selectivity to lower olefins in the MTO conversion, while its large cages allowed the rapid further cyclecondensation of active intermediates, polymethylbenzenes including hexamethylbenzene, resulting in a rapid deactivation. The UZM-9 containing copper and cobalt ions showed considerably slow deactivations. The interaction between transition metal ions and polymethylbenzene cation radicals, the active intermediates, generated in the MTO conversion stabilized the radicals and slowed down the deactivation of UZM-9.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.67-76
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• 1995

자기저항헤드용 Ni-Fe-Co/Cu/Ni-Fe-Co/Fe-Mn 다층박막에서 자기적 성질과 전기적 성질에 관하여 조사하였다. 저 포화자계에서 고 자기저항을 나타내는 스핀 밸브형 다층박막을 제작하기 위하여 Borond이 도핑된 p-type Si(100)기판위에 Ni-Fe-Co 단층박막과 Si/Ni-Fe-Co/Cu/Ni-FeCo, Si/Ni-Fe-Co/Fe-Mn 구조의 다층막을 제작하여 자기적 특성을 조사하였다. Ni-Fe-Co 단층박막의 자기적 특성은 고정된 아르곤 분압에서 박막의 두께 등에 의존성이 있는 것으로 나타났다. 또한 Si/Ni-Fe-Co($70AA$)/Fe-Mn 구조에서 Ni-Fe-Co와 Fe-Mn 계면에서의 두 자성층의 이방성 차이에 의해서 발생되어지는 교환자기이방성이 존재하였으며, 교환자기이방성자계값은 Fe-Mn 두께가 $150\AA$일 때 가장 큰 값을 나타내었다. Ni-Fe-Co texture와 교환자기이방성자계값은 Fe-Mn 두께가 $150\AA$일 때 가장 큰 값을 나타내었다. Ni-Fe-Co texture와 교환자기이방성자계값의 의존성을 알아보기 위하여 Ti, Cu를 바닥층으로 사용하였다. Ti을 바닥층으로 사용하였을 경우, 교환자기이방성자계값은 23.5 Oe 정도의 가장 큰 값을 나타내었다. XRD 분석결과, Ti 바닥층이 Cu 바닥층이나, 바닥층이 없는 경우와 비교하여 성막된 Ni-Fe-Co 자성층의 강한 fcc(111) texture를 형성하는 것으로 나타났다. 각각의 단층박막과 다층박막에서의 자기적 특성을 측정한 후, Si/Ti($50\AA$)/Ni-Fe-Co($70\AA$)/Cu($23\AA$)/Ni-Fe-Co($70\AA$)/Fe-Mn(150$\AA$)/Cu(50$\AA$)의 스핀밸브구조를 갖는 다층박막을 제작하였으며, 11 Oe의 낮은 포화자계값에서 4.1%의 고 자기저항값을 얻을 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.226-230
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• 2003

In this thesis I analyzed that V5.2 protocol function is effective to fulfill all of the services that are provided at the existing local exchange. I analyzed this in five methods that refer to ETSI inside patronage. I experimented turnaround time by Start-up method and verified V5.2 protocol function when Start-up. Also I confirmed stability of system by the reconstruction-ability experiment related E1 switch over. I verified V5.2 protocol function through PSTN call process that uses a special service test and local call simulator. As a result of experiment, I confirmed the best method when simultaneous Start-up. V5.2 protocol function was excellent and It becomes switch over at 1/1000 seconds when E1 is out of service. V5.2 protocol function was effective to fulfill all of the special services that are provided at local exchange and its long call process ability was superior to KT standard with 4 fails in 20000 calls. Through the experiment, it was proved that V5.2 interface will become a significant element of communication network when after LE side expanse of v5 interface ID with TDX-100 exchanger and the AN occurrences OOS by message transmission limit and call disconnect when E1 switch over are improved.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.36-44
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• 2003

This paper proposes a Viterbi decoding scheme without trace-back operations to reduce the amount of memory storing the survivor path information, and to increase the decoding speed. The proposed decoding scheme is a modified register exchange scheme, and is verified by a simulation to give the same results as those of the conventional decoders. It is compared with the conventional decoding schemes such as the trace-back and the register exchange scheme. The memory size of the proposed scheme is reduced to 1/(5 x constraint length) of that of the register exchange scheme, and the throughput is doubled compared with that of the trace-back scheme. A decoder with a code rate of 2/3, a constraint length, K＝3 and a trace-back depth of 15 is designed using VHDL and implemented in an FPGA. It is also shown that the modified register exchange scheme can be applied to a block decoding scheme.

• Journal of KIISE:Software and Applications
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• v.35 no.2
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• pp.128-136
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• 2008

Recognition of parallel structure at early stage of sentence parsing can reduce the complexity of parsing. In this paper, we propose an unsupervised language-independent probabilistic model for recongition of parallel noun structures. The proposed model is based on the idea of swapping constituents, which replies the properties of symmetry (two or more identical constituents are repeated) and of reversibility (the order of constituents is inter-changeable) in parallel structures. The non-symmetric patterns that cannot be captured by the general symmetry rule are resolved additionally by the modifier information. In particular this paper shows how the proposed model is applied to recognize Korean parallel noun phrases connected by "wa/kwa" particle. Our model is compared with other models including supervised models and performs better on recongition of parallel noun phrases.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.494-496
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• 1998

이 논문은 안전한 통신을 보장하고, 전자결재 기능을 제공하는 SEED(Secure Environment for Exchanging Digital Signatures)의 설계 구현에 대해 기술한다. SEEDS는 일반 기업이나 단체에서 근거리망을 통해 서류를 결재하고 교환하는데 개발된 전자결재스템이다. 따라서 SEEDS는 사무환경 특성에 적합한 시스템 구조와 암호화 알고리즘을 기반으로 하는 중재결재 방식을 사용하며, 결재된 서류뿐만 아니라 통신 메시지의 보안을 위해 새롭게 개발한 키 교환 메시지 전송 프로토콜을 사용한다.

• ETRI Journal
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• v.8 no.2
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• pp.117-123
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• 1986

TDX-1 RSS(Remote Subscriber Switch)시스팀은 여러지역에 산재되어 있는 원격지가입자를 모국 교환기에 경제적으로 수용 할 수 있도록 개발된 교환장치이다. RSS의 기본적 목적은 원거리 가입자에게도 TDX-1모국 가입자와 같이 전전자 교환기의 장점을 부여하고 전화망 구성에 장애가 되고 있는 가입자 선로의 제약요소와 케이블 비용 등을 대폭 경감시키는 데 있다. 본고에서는 TDX-1 RSS의 구조 및 기능을 개발 측면에서 기술하였다.

• Electronics and Telecommunications Trends
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• v.13 no.1 s.49
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• pp.14-20
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• 1998

본 논문은 대도시 전화망에서 루팅 효과, 통화량에 준한 망설계기법에서 전송시설의 경제적 규모, 그리고 투자비용 변화를 분석하기 위한 시뮬레이션 모델 개발에 관한 것이다. 모의시험 결과는 전화망에서 교환/전송에 소요되는 비용은 루팅방식의 변경에 따라서 크게 영향을 받으며, 고속 전송로 사용에 따른 규모의 경제효과가 클수록 망 구축에 소요되는 비용이 현저히 작아지는 것으로 나타났다.

• ETRI Journal
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• v.10 no.4
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• pp.75-88
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• 1988

본고는 CCITT에서 통신망의 운용관리를 위해 연구중인 TMN(Telecommunications Management Network)의 개념을 토대로 장차의 통신망에서 필수적으로 요구되는 ISDN 기능과 CCITT의 No.7 기능의 실현을 목표로 하고 국내외적으로 활발한 활용이 예상되는 대용량 전전자 교환기인 TDX-10이 현장에 적용될 경우의 효율적인 운용관리를 위해 요구되는 사항들을 망차원에서 유관센터들의 기능과 관련하여 분석하고, 시스팀화하여 TDX-10 운용 및 보전에 필요한 교환기 유지보수, 과금 및 트래픽 데이터처리, 교환기 DB관리의 다기능을 동시에 제공할 수 있는 운용관리 방식의 구조, 기능 및 TMN환경에서의 외부 환경과의 접속방법 등을 기술한다.