OFDM 시스템의 PAPR 저감을 위한 심벌 그룹핑 SLM 기법

최익녕,이현재,오창헌 한국기술교육대학교 2004 論文集 Vol.10 No.2

본 논문은 OFDM 시스템에서 PAPR (peak-to-average power ratio) 문제를 효과적으로 저감시키기 위하여 기존 SLM (selective mapping) 기법과는 달리 심벌 그룹핑 후 그룹별로 같은 스크램블 코드를 이용하는 새로운 방법을 제안하고 성능을 분석하였다. 기존의 SLM 기법은 IFFT단에 들어가는 OFDM 심벌을 여러 개의 스크램블 코드에 의해 랜덤화 시켜 PAPR 중 작은 값을 선택하여 전송한다. 그러므로 SLM 기법은 스크램블 코드만큼 부가 정보를 전송함으로 대역의 손실이 발생한다. 그러나 제안된 심벌 그룹핑 SLM 기법은 부반송파들을 M 개로 그룹화 하여 동일한 스크램블 코드를 사용함으로써 그룹화한 OFDM 심벌의 개수만큼 부가정보 데이터를 줄일 수 있고, SLM 기법에서 사용한 숫자만큼 스크램블 코드를 사용한다면 기존의 SLM 기법보다 PAPR 성능을 더 개선할수 있다. In this paper, we propose and analyze a new scheme which uses the same scramble codes to each group after symbol grouping to reduce the PAPR (peak-to-average power ratio) problem in OFDM system. The conventional SLM scheme randomizes OFDM symbols entered into IFFT block by several scramble codes and then transmits the lowest one among PAPRs. Therefore, the SLM scheme results the loss of bandwidth because of transmitting additional information as many as scramble codes. The proposed scheme can reduce the additional information as many as the number of grouped OFDM symbols by using same scramble codes after M grouping of sub-carriers. It can also improve PAPR performance more than conventional SLM scheme when we use scramble codes as same as those numbers of SLM scheme.

퍼지제어 스템의 입출력이득요소 설계 방법

최한수,정창규,정헌 조선대학교 에너지.자원신기술연구소 1997 에너지·자원신기술연구소 논문지 Vol.19 No.2

Fuzzy controller consists of rule base, membership function, fuzzy inference, defuzzification and I/O scaling factors. Performance of fuzzy controller depends on design method of then parameters. Especially, I/O scaling factor effects directory on the performance of fuzzy controller, but get out those value can not be obtained with more systemical method. A method of I/O scaling factor design for fuzzy controller is proposed in this paper. The proposed method is for nonlinear input scaling factor and variable output scaling factor. Purpose of this research is to make a control system have faster rising time, a smaller overshoot and a shorter settling time. Proposed fuzzy controller is evaluated by computer simulation on the 1st order and 2nd order process with various I/O scaling factors, and satisfactory results showed.

선천성 후비공 폐쇄증 : 7예의 분석

김창훈,이정권,최윤석,유신영,윤주헌 대한이비인후과학회 2000 대한이비인후과학회지 두경부외과학 Vol.43 No.3

都市內 新築建物의 分布 및 新築 密集地域의 空間的 特性 : 晉州市 江北地域을 中心으로 Focused on Chinju Kang-buk District

文泰憲,崔昌榮 慶尙大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.15 No.-

The aim of this study is to analyze the distribution characteristics of new buildings in city and the influence that a newly built building might give to the construction of neighboring buildings. For these purpose, the nearest distance, new building density by the land price and distance from the crossroad and main road were analyzed. Because our study needs to control huge data and measure the exact spatial distance, we established GIS data with parcel unit of Chinju city. The results of this study are as follows. First, the highest frequency of nearest distance was 30∼60m. So, new buildings are giving impacts on the construction of neighboring new buildings. Second, the density of new buildings from the crossroad is higher near the crossroad and main road. Third, the built-up regions of high density have different characteristics comparing to other regions. Therefore, when we make a plan or decision-making for urban develop, we have to consider the characteristics of each region. Finally, this study suggested the needs of further analysis to find the common characteristics of the construction tendency in a urban space.

셀(Cell) 단위 도시성장 모델링

문태헌,최창영 대한건축학회 2003 대한건축학회논문집 Vol.19 No.7

Excessive concentration of population into city has resulted in urban sprawl and environmental deterioration of suburbs in some cities. To prevent our cities from unfavorable situation of urban development, we are greatly in need of understanding of the city's growing appearance in the future. This paper examines an urban growth model of Jinju City. Existing urban growth models elaborated have difficulties in dynamic simulation. Easy geographic visualization and spatial exploration is another hard barriers to overcome. For these reasons we integrate Cellular Automate (CA) as an urban dynamic model and Geographic Information System (GIS) for visualization. Cell-based CA model was programmed with Visual C++ under the transition rules proposed with 1918 to 1986 growing trend of Jinju City. CA model constructed then was simulated as changing parameters into three cases. As a result, a CA model made was proved to regenerate urban growth as high as 93% of accuracy.

지연유합과 불유합에서 저신호 강도 초음파의 유용성

윤여헌,김종오,고영도,유재두,정준모,오종건,방한천,최창호,신명철 대한골절학회 2003 대한골절학회지 Vol.16 No.1

목 적 : 저 신호 강도 초음파를 이용한 지연유합과 불유합의 치료에 대한 유용성을 알아보고자 하였다. 대상 및 방법 : 2001년 7월부터 2002년 5월까지 본원에 내원한 지연유합 7례와 불유합 8례를 대상으로 5개월간 저 신호 강도 초음파로 치료하여 5개월후 골유합 여부를 알아 보았다. 결 과 : 총 15례 중 대퇴골 간부 2례, 경골 간부 1례, 상완골 간부 1례, 요골 1례의 지연유합에서 골유합을 얻었고 대퇴골 간부 불유합 3례에서 유합을 얻었다. 지연주합은 71%의 유합율을, 불유합은 37.5%의 유합율을 보였다. 결 론 : 저 신호 강도 초음파는 골유합을 촉진 시킬 수 있으며 지연유합에서 시도해 볼 만 하나 불유합 치료를 위해서는 보다 많은 연구가 필요 하다. Purpose : To evaluation of usefulness of low-intensity ultrasound for nonunion and delayed union. Materials and Methods : For 5 months, we treated 7 delayed union and 8 nonunion using low-intensity ultrasound. After 5 months, in checked X-ray AP and Lateral view, when cortical bridge formation was done, we through union. Results : In 7 delayed union, 5 cases-2 femur, tibia, humerus, radius were healed. In 8 nonunion, 3 femur nonunion were healed. Union rate was 71% in delayed union 37.5% in nonunion. Conclusion : we thought that the low-intensity ultrasound has capacity of induction of union and was considered as the method of treatment for delayed union.

수면확성기의 음향특성에 관한 연구

이창헌,문종욱,박용석,최찬문,서두옥 제주대학교 해양연구소 1998 해양자원연구소연구보고 Vol.22 No.-

To obtain the fundamental data on a surface speaker made to lure fish school by pure sound, three surface speakers were made of moving coil driver units of 75W and 50W respectively. Their frequency characteristic was measured in the range of 200 - 4mHz that could be used in luring fish school. The results of the measurements in air and sea are follows. 1. The input and output wave forms of a surface speaker were similar to each other in measurement frequencies in air. Then sound pressure of a surface speaker made of 75W driver units among them was over 130dB(0dB re 20μ Pa) in the range of 300 - 400Hz maximally. 2. When the surface speaker with 75W driver units emitted the measurement frequencies at sea. Sound pressure classified by the depth of water were over 140dB at 1m and 120dB at 20m(0dB re 1μ Pa) respectively.

Nondimensional modelling of 2D beam for slope discontinuity problem in ANCF

Ji-Heon Kang,이재욱,Jinseok Jang,Chang Young Choi,김건우 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Various mechanical and structural systems possess slope discontinuity. Some bodies with slope discontinuity can be modeled using absolute nodal coordinate formulation, which can accurately express the rigid body mode when using the element and global shape functions. However, at the intersection of slope discontinuities, it is not easy to construct the equation of motion because the orientation changes. The problem of modeling at the intersection can be solved by defining the global slope vector in the body coordinate system instead of the element coordinate system. The analysis time in absolute nodal coordinate formulation is mostly greater than that in floating frame of reference formulation owing to the highly non-linear stiffness matrix. In this study, based on the work of Shabana and Mikkola, the analysis efficiency was demonstrated using the nondimensional model for the slope discontinuity problem in the absolute node coordinate system.

수중 가청음에 대한 멸치 어군의 행동 반응

이창헌,문종욱,박용석,최찬문,서두옥 제주대학교 해양연구소 1998 해양자원연구소연구보고 Vol.22 No.-

A field experiment was carried out to confirm the effect of underwater sound on the luring of fish school using a surface speaker at the coast of Cheju Island. Underwater sounds that were emitted for the luring of fish school were the pure sound of which frequencies were 200Hz and 300Hz. 1. The sound pressure level of 100Hz. 200Hz. 300Hz. 500Hz and 1000Hz classified by the depth of water at sea were 95dB. 100dB. l00dB 80dB and 60dB at 1m. 90dB. 95dB. 88dB. 70dB and 45dB at 10m. 87dB, 90dB. 82dB. 65dB and 42dB at 20m respectively. 2. The effect of the emitted pure sound of 200Hz and 300Hz was remarkable for luring of fish school in about 30 minutes after sound emission. Then Sound pressure was 120 - 130dB. The lured fish school was the shoal of anchovy 3. The fact that anchovy school geathered at 200Hz and 300Hz suggested that this fish school did not show sensitive response to the change of frequencies.

10주간의 체계적 운동이 노인들의 골밀도에 미치는 영향

이규문,최종환,김창범,김태헌 忠北大學校 平生體育硏究所 1997 平生體育硏究所 論文集 Vol.9 No.-

An experimental study was designed to investigate the effects of 10-weeks exercise on the bone mineral density (BMD) in women (ages 55 to 74). The subjects were placed into two age groups; middle aged group(n=19, 62.2±2.5 yrs) old group(n=16, 69±2.3 yrs). All subjects completed the bone mineral density test ( Radius and Ulna) by computed tomography both prior to and immediately following 12-weeks program. Both experimental groups participated in an 12-week exercise program consisting of three 80-min supervised exercise bouts a week. A pairs T-test was used to examine differences between pre-and post-test scores in the bone mineral density, depending on each age group. First the significant improvement (1.7%) appeared on BMD in all subjects together after 10-weeks exercise. Specifically, the middle aged group showed statistically significant increase(1.2%) between pre-and post-test scores in he bone mineral density after 10-weeks program. However, even though the improvement (2.2%) of BMD in the older group was not significant in statistics, the improvement(2.2%) of BMD in the older group is bigger than the improvement (1.2%) of BMD in the middle aged group. Therefore, the results suggest that improvements in BMD may be affected by acute exercise and may support the affective beneficence of exercise for older populations.