IEEE 802.11a 기저대역 프로세서의 설계 및 구현

김상인,최원철,이제훈,조경록 충북대학교 컴퓨터정보통신 연구소 2006 컴퓨터정보통신연구 Vol.14 No.2

본 논문에서는 IEEE 802.11a 표준안에 적합한 기저대역 프로세서를 설계하였다. 프로세서의 크기 감소 및 성능 향상을 위해 새로운 알고리즘이 적용되었다. 구현된 IEEE 802.11a baseband processor는 기존의 OFDM 방식 모뎀의 성능향상을 위해 고속의 IFFT/FFT를 이용하고, 다중경로 채널과 페이딩에 강한 새로운 채널 보상기법과 등화기, tan^(-l) 기법을 이용한 동기회로 그리고 에러 예측 회로를 사용한 비터비 디코더등 개선된 알고리즘을 이용하여 성능향상을 도모하였다 설계된 기저대역 프로세서의 구현 및 검증을 위해 SoC플랫폼을 이용하였다. 플랫폼 기반의 IEEE 802.11a WLAN을 설계하기 위한 환경은 기저대역 프로세서 칩을 테스트하기 위한 테스트 보드와 MAC을 이행할 SoC 플랫폼으로 구성되어 있다. 설계된 IEEE 802.11a baseband processor는 AWGN, 다중 경로 페이딩 채널에서 데이터 전송을 확인하였다.

전산유체 기법을 이용한 용존공기부상법에서의 접촉도 조건변화에 따른 충돌효율평가

김성훈,유제선,박희경 대한상하수도학회 2004 상하수도학회지 Vol.18 No.2

Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard k-ε mode Ⅰ(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.

전산유체 기법을 이용한 DAF 부상조에서의 수리 특성 고찰

김성훈,유제선,김영미,박희경 대한상하수도학회 2002 상하수도학회지 Vol.16 No.4

Dissolved air flotation is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. DAF is found most effective in treating algae and lower density flocs that are hard to remove in sedimentation process. Some researcher reports the results of an experimental study which examined the flow within the flotation zone of a DAF tank (ONeill at al., 1997). I would be concluded that, in general, the flow within flotation zone is robust and that differences in the performance of individual DAF tanks must be the result of processes occurring within the contact zones of these tank, not as the result of flotation processes. In this research, the authors thought that the efficiency of the DAF process is strongly related to bubble size. It means bubble rising velocity at the air injection nozzle is most important factor of DAF process. However, bubble movement in DAF tank is somewhat complicate, so it is hard to make up conceptual model through simple mass balance as other researchers did (Leppinen at. al., 2000). For the modeling of turbulent 2-phase flow in the tank, the standard k-ε model was used in CFD code because it is widely accepted and the coefficients for the model are well established. This model uses the eddy-viscosity hypothesis for the turbulence. As the result of this study, the authors concluded that bubble size and its rising velocity is very important factor of DAF process and the recycle ratio must be also consider for the flotation zone parameter. Also, For the improved model, relation between turbulent intensity and bubble-particle attachment must be studied.

반도체 레이저의 온도 및 주입전류 의존성에 관한 연구

김의훈,김필수,이제형 漢陽大學校 基礎科學硏究所 1992 基礎科學論文集 Vol.11 No.-

반도체 레이저의 온도와 주입전류 변화에 따른 방출스펙트럼의 특성을 조사하고 파장조정 가능성을 연구하였다. 실온에서 피크파장 780nm를 가지는 Mitsubishi사의 GaAlAs계의 레이저 다이오우드에 대해 주입전류를 일정하게 유지하고 온도를 변화시켰을 때의 방출피크파장은 계단적으로 증가하였으며 파장의 의존도는 0.20nm/℃였다. 온도를 일정하게 유지하고 주입전류를 변화시켰을 때의 방출피크파장 역시 계단적인 변화양상을 보였으며 파장의 전류 의존도는 0.11nm/mA였다. 한편 레이저 다이오우드의 문턱전류는 다이오우드의 온도 증가에 따라 거의 지수함수적으로 증가하였다. 온도와 주입전류 변화로 얻은 최소 방출파장은 770nm이었다. Spectral characteristics and wavelength tunability of a semiconductor diode laser have been studied by examining the wavelength dependence on temperature and injection current. The results show that the output peak wavelength from a Mitsubishi GaAlAs laser diode increases stepwise with increasing temperature at constant injection current, showing the wavelength dependence on temperaure of 0.20nm/℃. On the other hand, the output peak wavelength also varies stepwise with increasing injection current at constant temperature, representing the wevelength dependence on injection current of 0.11nm/mA. The measured threshold currents of the diode laser increase exponentially as a function of temperature. By control of temperature and injection current of laser diode, the output peak wavelength can be attained down to 770nm.

순수 에탄올 경화요법을 통한 경부 및 견부 임파관종 치험 1 예

김동익,허승,이병붕,도영수,이순정,박제훈 대한혈관외과학회 1998 Vascular Specialist International Vol.14 No.2

Cystic lymphangioma is congenital anomaly originated from the lymphatic system. It occurs at head and neck area mainly. But its unusual location is possible. Treatment of cystic lymphangioma was surgical removal, but recently nonsurgical approach were studied, including sclerotherapy. Bleomycin, OK-432, and absolute ethanol were used as sclerotherapeutic agents. A 31 year-old female patient was treated by sclerotherapy with absolute ethanol for a cystic lymphangioma in neck and shoulder region. She had detected a mass in neck and shoulder region 8 years ago and had been done excisional surgery twice, 7 years and 4 years ago respectively. She had a 5 ×4×12 cm sized mass, that was recurred, in her neck and shoulder region. She had sclerotherapy twice in a 3-month interval. Its size decreased 2 cm in diameter from 12 cm.

물질사용장애 환자의 색다른 것을 추구하는 기질

김미영,박제민,윤경일,유택규,권도훈,김성곤,김명정,장기용 대한생물치료정신의학회 2001 생물치료정신의학 Vol.7 No.1

In this study, the relationship between substance use and high-novelty seeking was tested using Cloninger et al's 240-items Temperament and Character Inventory(TCI) in 34 substance users(32 methamphetamine and 2 cocaine dependence disorders), 80 normal controls and 48 schizophrenics Demographic characteristics and substance use-related past history were taken by semi-structured interview. Subjects were aged 18-45 and general psychopathology was screened by Symptom Checklist 90 revised. The results were as follows. 1) Among temperament subdivisions in the TCI, novelty seeking(NS) was significantly higher in the substance users(22.1±4.9) than the normal controls(18.0±5.0) and the schizophrenics(15.6±3.3). There were no significant differences in other temperament subdivisions such as harm avoidance, reward dependence and persistence, neither character subdivisions such as self-directiveness, cooperativeness and self- transcendence. 2) A significant inverse correlation was found between NS and age both in the substance users(r=0.274) and the normal controls(r=0.468). This study suggested that the biogenetic temperament characteristics in substance use disorder were related with their high novelty seeking, not low harm avoidance.

남자 알코올 의존 환자의 기질적 특성에 관한 연구

김성곤,민영기,이덕기,김미영,송영상,권도훈,고영훈,박제민,정병선 대한생물치료정신의학회 2003 생물치료정신의학 Vol.9 No.1

목 적: 본 연구의 목적은 한국인 남자 알코올 의존 환자의 기질적 특성을 Temperament and Character Inventory(TCI)를 이용하여 조사하는 것이다. 방 법: DSM-Ⅳ 진단 기준에 맞는 알코올 의존 환자 30명과 정상인 36명을 대상으로 연구학적 특성을 조사하고, 기질적 특성을 한글판 TCI를 이용하여 조사하였다. 모든 대상자의 나이는 30~60세였다. 결 과: 1) 두 군간 평균 나이는 유의한 차이가 없었으나, 교육 정도와 결혼을 유지하고 있는 비율 및 취업률은 알코올 의존군이 정상 대조군에 비해 유의하게 낮았다. 2) 알코올 의존군에서는 정상 대조군에 비해 Harm Avoidance(HA) 점수와 Self-transcendence(ST)점수는 유의하게 높았으며, Self-directiveness(SD)점수는 유의하게 낮았다. 3) 알코올 의존군 내에서의 각 척도들 간의 상관관계는, HA와 SD 점수, HA와 Persistence(PE) 점수, ST와 SD 점수는 각각 유의한 음의 상관관계, ST와 PE 점수, SD 점수와 Cooperativeness(CO) 점수, Reward Dependence(RD)와 CO 점수는 양의 상관관계를 보였다. 결 론: 이러한 본 연구의 결과는 한국인 남성에서 수줍음을 잘 타며, 걱정도 많고, 염세적이고 쉽게 피로해지는 기질적 특성이 알코올 의존과 연관성이 있음을 의미한다. Objectives : The purpose of this study was to assess the temperament of male parients with alcohol dependence. Methods : The subjects were 30 patients who met DSM-Ⅳ criteria for alcohol dependence and 36 normal controls. All subjects completed Temperament and Character Inventory(TCI) which was developed by Cloninger. Results : 1) The educational level, marital status, and occupation in alcohol dependence group were significantly lower than those of normal control group, but there was no difference in the age between two groups. 2) Among the scores of TCI, the score of harm avoidance(HA) and self-transcendence(ST) were significantly higher in the alcohol dependence group than in the normal control group. 3) In the alcohol dependence group, a significant negative correlation among the scores of TCI was between HA and SD, HA and Persistence(PE), ST and SD, and positive correlation between ST and PE, SD and Cooperativeness(CO), Reward Dependence(RD) and CO. Conclusion : These results suggest that shy, fearful, pessimistic and fatigable temperament are related to developing alcohol dependence in Korean males.

정상 성인에서 갈근(Radix puerariae)의 장기투여가 혈중 알콜 농도에 미치는 영향

박제민,김지훈,김명정,김성곤,정영인 大韓神經精神醫學會 1996 신경정신의학 Vol.35 No.6

알콜 의존에서 알콜 소비량을 감소시키고 음주 재발을 방지하는데 효과가 있다는 약물들이 몇 가지 있으며 갈근이 알콜 의존증의 치료에 효과가 있다는 자료들이 있다. 저자들은 정상 성인을 대상으로 알콜을 섭취하게 한 후 갈근 투여 전, 후의 혈중 알콜 농도를 비교함으로써 갈근이 알콜 대사를 방해하여 혈중 알콜 농도를 상승시키는지를 검증하고자 하였다. 알콜을 비롯한 약물 남용이나 의존증이 있거나 기타 정신 질환이 없고 주요 신체질환이 없는 20∼29세 남자 의과 대학생들을 대상으로 하였다. 대상자는 모두 25% 알콜을 3ml/kg(100%알콜 0.75ml/kg)을 마시게 한 후 투여 전, 투여 후 10, 30, 60, 90, 그리고 120분에 혈중 알콜 농도를 측정하게 한 다음 14일간 갈근 하루 6g을 투여한 후 첫날과 같은 방법으로 알콜을 복용하게 한 후 알콜 혈중 농도를 측정하여 약물 투여 전, 후의 알콜 혈중 농도를 비교한 결과 갈근 투여 후에 음주시 30, 60, 90, 그리고 120분에 혈중 알콜 농도가 유의하게 상승하였다. In alcohol dependence, some drugs reduce alcohol consumption and prevent the recurrence of alcohol drinking. There were some evidences that Radix puerariae was effective in the treatment of alcohol dependence. We studied the effect of Radix puerariae on blood alcohol concentration in healthy adults. The subjects were medical students, who did not have major physical disorders, drug abuse or dependence including alcohol, and other psychiatric disorders. After drinking 25% alcohol 3ml/kg, all subjects were measured for blood alcohol concentration at 0, 10, 20, 30, 45, 60, 120 minutes by Alco-sensor Ⅳ. Next day, all subjects were made to take Radix puerariae 6g/day(3g bid) for 14 days. And then blood alcohol concentration were measured by the same method. The results were significant increase in blood alcohol concentration at 30, 60, 90 and 120 minutes.

운동전략이 기립자세의 기능적 전방 팔뻗기에 미치는 영향

박제상,권오윤,최흥식,김택훈 한국전문물리치료학회 2000 한국전문물리치료학회지 Vol.7 No.1

The purpose of this study is to determine whether movement strategies affect functional forward reach distance in a standing position. Forty-seven healthy subjects were selected for this study: 23 men and 24 women, with an average age of 22.3. Functional forward reach distances were measured as hip strategy and squat strategy(included knee and ankle movement strategy) in a standing position, respectively. The mean values of functional forward reach distance in hip strategy, squat strategy were 33.57㎝, 29.48㎝, respectively. There was significantly difference in functional forward reach distance between hip strategy and squat strategy(p<.001). There was no difference of functional forward reach distance between male and female in hip strategy, but there was significant difference in other strategy(p<.05). These results suggest that movement strategies should be considered during functional forward reach test in standing. Further study is required to determine whether movement strategies affect functional reach distance in elderly and disabled groups.

Dissolved Air Flotation(DAF) 접촉조의 수리동력학적 조건이 입자의 제거에 미치는 영향

유제선,김성훈,신은허,박희경 대한상하수도학회 2003 상하수도학회지 Vol.17 No.1

Hydrodynamic conditions for optimum solids capture within the contact zone, which are governed by the geometry and flow, are not yet well understood. In this research, dimensionless parameters which represent hydrodynamic conditions in the contact zone were derived, using the Buckingham π theorem. Those parameters are Reynolds No. (Re), Froude No. (Fr), Weber No. (We), Local Weber No., and Bubble Capacity No. (Bc). The particle removal rate was investigated by changing each value of the dimensionless parameters. The experimental results indicate that particle removal rate, when gravity dominates and the flow is semi-turbulent (Fr < 0.3, Re < 8000), is higher than when inertia dominates and flow is turbulent. For the We, higher removal rates were obtained in the range of the We < 40. Relative to the Local We, smaller bubbles which are influenced more by surface tension than inertia, demonstrated a higher particle removal rate than larger bubbles. For the Bc, the optimal range is from 0.3 to 0.5. We suggest that these dimensionless parameters can be used to diagnose the performance of and to design a DAF reactor.