• Journal of Broadcast Engineering
• /
• v.10 no.3
• /
• pp.401-412
• /
• 2005

We propose and design the algorithms of symbol timing recovery, carrier recovery, and equalization for the receiver of S-DMT cable modem, which supports more channels and better symmetric mutimedia services over HFC network. We evaluate the performance of the concatenated entire receiving system of 16QAM, 64QAM in the mixed noise channel of AWGN, ISI and impulse. The result of evaluation shows those algorithms work correctly and designed S-DMT receiver has good performance. We also verify the designed system has excellent immunity against impulse noise channel of practical Cable TV networks by the result of simulation with the parameters of impulse internal $\varepsilon$ and noise power $\gamma^{k}$.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.985-988
• /
• 2009

본 논문에서는 3GPP-LTE 상향링크 기술인 SC-FDMA에서 적응형 등화기 성능에 대해 알아보았다. SC-FDMA의 등화기에서 계산량을 줄여 효율성을 높이는 방법으로 ZF(Zero Forcing)과 MMSE(Minimum Mean Square Error)를 이용한 스위칭 기법을 제안하고, 제안한 시스템에서의 성능을 비교 분석하고자 한다. 제안한 스위칭 기법을 사용함으로써 SNR이 낮을 때는 MMSE를 이용하여 잡음에 대한 영향을 최소화 시켜주고, SNR이 높을 때는 ZF을 써서 상대적으로 복잡도가 적은 등화 기법을 통해 전체적인 시스템 복잡도를 줄여 효율성을 높이고자 한다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.594-597
• /
• 2007

바이오매스를 이용한 분산형 발전 및 에너지화의 경우 기존의 연소법은 단순 열에너지의 이용과 스팀터빈을 이용하는 대규모 시설이 요구된다. 반면 가스화의 경우 가연성 합성가스 생성을 통하여 소규모 분산형 발전이 가능하며, 생성가스를 이용하여 다양한 응용이 가능하다. 기존 상향류식 가스화의 경우의 바이오매스 가스화시 목질계 내 리그닌 성분으로 인하여 다량의 타르가 발생하여 후단 처리 설비에 어려움이 있다. 본 연구에서는 하향류식 가스화 방법을 통하여 목질계 바이오매스의 가스화 특성을 알아보았다. 가스화기 하부로 배출되는 합성가스의 온도는 대략 1000$^{\cdot}C$까지 유지할 수 있었으며, 생성되는 합성가스의 발열량은 약 $1300kcal/Nm^3$의 수준으로 얻을 수 있었다. 또한 발생되는 타르는 $5{\sim}15ppm$ 정도로 기존 상향류식에 비해 매우 적은양의 타르가 발생함을 확인할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.7
• /
• pp.1293-1295
• /
• 2015

In this letter, an adaptive multi-antenna channel estimation scheme is proposed for uplink multiuser environments such as LTE-A systems to accurately estimate time-varying channels within an affordable complexity. It is confirmed that the proposed channel estimator can achieve accurate channel tracking performance even when various time-varying channel environments and traffic patterns are provided.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7A
• /
• pp.686-693
• /
• 2007

In this paper, we describe how to set up/down step-size in open loop power control for WiBro reverse link. Since open loop power control does not use feedback information, it is difficult to efficiently use wireless resource with accurate power control. We also provides a method of estimating levels of noise and interference. With numerical investigation, asymmetric up/down power-control step-size is shown to be promising to achieve high sector throughput as well as low error rate.

• Korean Journal of Heritage: History & Science
• /
• v.54 no.1
• /
• pp.280-301
• /
• 2021

Chogak has been regarded as originating from the paintings decorating building elements. Various curved shape drawings that were first seen in the paintings of Goguryeo tomb murals evolved into the vine patterned Dancheong of Geuklakjeon in Bongjeongsa. Cheomcha of Geuklakjeon was chiseled with Yeonhwadusik relievo at the bottom on top of Dancheong, and this was the beginning of Cheomcha-Chogak. Also, Cheomcha, which was carved with a preliminary vine patterned Chogak in Daeungjeon in Bongjeongsa, opened the era of engraving Chogak directly on the surface of structural elements. Since then, vine patterned Chogak was a significant decoration technique for the Cheomcha of traditional wooden construction for a long time. Because Jeongjagak is a structure that was continuously built between the end of the Japanese invasion of Korea in 1592 and the late Joseon Dynasty, the transition of Cheomcha-Chogak over time can be seen through Jeongjagak architecture. The early Cheomcha-Chogak presents stems that climb up (Upbound-type) towards the headpiece on a column, while stems of Chogak later reversed direction to descend (Downbound-type) from the headpiece. This study examined the transition process and reasons for the change, with a focus on the findings above, and identified a new type of Chogak that is unrelated to the direction type and was adopted during the transition from Upbound-type to Downbound-type. The new type appeared when the Jeongjagaks for the Royal Tomb of Kyeongjo and those of the Injo were built, and it matches with the transitional period wherein lotus vanishes from Hwaban-Chogak. The study also inferred that the direction change of Cheomcha-Chogak stems was caused by the separation of vine patterned Chogak, carved with a two-stepped inner Ikgon, into both upward and downward from the headpiece, and this led to the changes that manifested as the inside of Choikgong being the Downbound-type Chogak and the variegated vine patterned Chogak of Choikgong affecting the direction of Cheomcha-Chogak. This is the follow-up study of "A Study on the Hwaban-Chogak of the Neungwon-Jeongjagak," a paper published in 2018, and is limited in n that Cheomcha, the focus of the research, is just one of the construction elements of Jeongjagak. The entirety ofChogak cannot be understood only by observing Cheomcha.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.5
• /
• pp.87-99
• /
• 2015

Prior hardware-centered rural development projects implemented top-down rural community regeneration via the local government in accordance with central government agency policies. To improve this, software-centered projects have been promoted since 2000. With central agency-led rural development projects changing into local government-led ones, rural community regeneration has been built per village. Although rural community regeneration projects appear to have implemented a bottom-up development currently, the top-down development procedures being facilitated by the intervention of administrative institutions have not disappeared. In this regard, the purpose of this research thesis is to effectively perform bottom-up development methods that go one step further from the current process of rural community regeneration. As the research site, this thesis selected Geochang, which has difficulties in being steadily maintained and operated despite the development of various rural community regeneration projects. Subsequently, it determined the current status and substantial analysis of a project of the rural community regeneration in Geochang through 1:1 interviews with civil servants in charge of administration as well as conducted a prior study on rural resident awareness of rural community regeneration through a survey of village head members and in-depth interviews with rural residents. Based on these data, a 10 times-round table conference was held under the participation of pertinent civil servants, professionals and rural residents to select practical strategies for cooperative rural community regeneration in Geochang as five key areas: local food, culture & welfare, rural villages, community development, and urban and rural interchanges. In addition, it is considered that the project of building villages must be implemented by establishing steadfast administrative co-operation systems, strengthening rural residents' participation capacities and supporting professionals' systemic integrated operation and maintenance. By doing so, this research thesis sought to determine practical strategies in the cooperative rural community regeneration in Geochang. It is expected that bottom-up development rural community regeneration will be built and introduced in each rural community in the future.

• Journal of the military operations research society of Korea
• /
• v.34 no.2
• /
• pp.143-162
• /
• 2008

This paper aims to formulate the method of estimating the wartime stockpile requirement of 155mm self-propelled artillery including intelligent ammunition for armored vehicles, currently being developed. The usual method of utilizing war-game simulation results in considerable margins in expected occupancy ratio between ground forces and air forces for each weapon system for armored vehicles. Also, the method tends to produce excessive output greater than the minimal stockpile requirements; therefore, the study aims to overcome limitations like these by the allocation method for each weapon system according to targets. This allocation method is better than war-game simulation method.

• Journal of Broadcast Engineering
• /
• v.2 no.2
• /
• pp.182-193
• /
• 1997

In this paper, we propose technical and structural solutions for various problems in two-way digital communication services in CATV networks by actual field tests. The two-way digital communication services include VOD, video conferencing, distance learning, interactive game and internet service. We investigate the quality of T -1 level 0.544 Mbps) upstream digital signal while varying the number of subscribers in three different cells in accordance with ITU-T G.821. Based on this investigation, several ways to cope with the problems identified are suggested.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.6
• /
• pp.17-26
• /
• 2009

In national defense, established information systems are mainly based on simple information processing, such as mass data query. They have thus lacked intelligent ability of information and knowledge representation ability. We therefore need the research about the construction of military ontology which is the main topic for knowledge construction. Military ontology can help us develop the intelligent national defense information system which can search and manage information efficiently. In this paper, we present the six-step bottom-up approach for military ontology extraction, then we apply this approach to one of military domain, called national defense educational training, and finally implement it using $Prot\acute{e}g\acute{e}$ which is one of the most useful ontology development tool.