이동전화 혼신개선을 위한 주파수 재사용 패턴에 관한 연구

박창렬,문병현 대구대학교 과학기술연구소 1995 科學技術硏究 Vol.2 No.1

주파수 자원이 한정된 열악한 무선환경하에서 오늘날 AMPS방식의 셀룰러 이동전화 시스템에서는 급증하고 있는 가입자 수요에 대처하기 위해서는 효율적인 셀 계획 및 채널할당이 무엇보다도 중요하다. 특히 트래픽 밀집지역인 대도시의 경우 급증하는 이동전화 가입자 수요에 대처하기 위해서 시스템 용량만을 고려한 주파수 재사용패턴을 사용한다면 주파수 간섭으로 인한 혼선문제가 더욱 심각해질 수 밖에 없다. 본 논문에서는 지형과 도심환경을 고려한 셀룰러 이동전화 시스템에서 N=7과 N=5의 주파수 재사용 패턴을 사용하였을때 동일채널간섭비를 대구광역시에 적용 비교 분석하였다.

일기엔트로피 및 정보비에 의한 장마기의 일기대표성 설정 : 서울, 대구, 광주, 충주, 부여를 중심으로 Focused on Seoul, Taegu, Gwangju, Chungju, Puyo

박현욱,문병채 한국환경과학회 2003 한국환경과학회지 Vol.12 No.4

The seasonal variation and frequency of rainfalls of Korea peninsula in Changma period show strong local weather phenomenon because of it's topographical and geographical factors in Northeast side of Asia. Based on weather entropy(statistical parameter)-the amount of average weather information-and information ratio, we cal define each area's weather representativeness, which can show us more constant form included topographical and geographical factors and seasonal variation. The data used for this study are the daily precipitation and cloudiness during the recent ten years(1990-1999) at the 73 stations in Korea. To synthesize weather Entropy, information ratio of decaying tendency and half-decay distance, Seoul's weather representativeness has the smallest in Summer Changma period. And Puyo has the largest value in September.

Indium이 도핑된 Si/CeO_2/Si 박막의 발광 현상

문병식,김종걸,양지훈,박종윤 성균관대학교 기초과학연구소 1998 論文集 Vol.49 No.-

Visible light with about 500 nm was observed from the indium doped Si/CeO_2/Si thin films at room temperature. CeO₂, indium, and silicon were in sequence deposited on the Si(111) substrate using electron beam evaporation. As the indium was increased the peak intensity of 500 nm was increased. After furnace annealing in nitrogen at 1100℃ the peak was observed at 400 nm. Secondary ion mass spectrometry(SIMS) showed the mixed layer of CeO₂, indium, and silicon. It seems that the peak around 500 nm would come from the mixed layer.

급성 출혈성 대장염으로 오인된 궤양성 대장염 1예

문희정,장병익,김승범,이호찬,박재현,은종렬,김태년 영남대학교 의과대학 2008 Yeungnam University Journal of Medicine Vol.25 No.2

Ulcerative colitis (UC) is a chronic inflammatory disorder of the gastrointestinal tract that affects the large bowel, Its etiology remains controversial. However, an infectious or immunologic origin is considered the primary cause. The onset of UC is typically slow and insidious, but some patients may present acutely with symptoms mimicking infectious colitis. We report a case of ulcerative colitis mimicking acute hemorrhagic colitis at initial presentation. A 60-year-old man was referred to Yeungnam University Hospital for bloody diarrhea and abdominal pain. Sigmoidoscopy revealed mildly edematous mucosa in the rectum and hyperemic mucosa with petechiae in the sigmoid colon. The patient was treated with antibiotics for several days, and his symptoms improved. However, after one month, his bloody diarrhea relapsed. Follow-up sigmoidoscopy revealed mucosal friability in the rectum and sigmoid colon. He was diagnosed with ulcerative colitis, and his symptoms were improved with mesalazine and a steroid enema.

Fractal 차원에 의한 표면경화면과 마찰면의 형태해석

문병주,조연상,옥철호,박흥식,전태옥 동아대학교 생산기술연구소 2001 生産技術硏究所硏究論文集 Vol.6 No.1

The determination of surface middleography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe middleography of various rubbed and hardened surface, the wear test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to rubbed and hardened surface of laser modified steel with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. middleography of rubbed and hardened surface can be effectively obtained by fractal dimensions.

필름형 염료감응태양전지용 AZO 투명전도막의 개발

박병욱,성열문,추영배,곽동주 경성대학교 공학기술연구소 2008 공학기술연구지 Vol.15 No.-

Recently, much interest has been paid in using plastic materials for replacing glass substrates with increasing applications for large scale flexible flat panel display and flexible film-typed dye sensitized solar cell(DSCs) In particular, flexible film-typed dye sensitized solar cell(DSCs) has attracted much interest because it can be applied to a smart window, a wearable PC as a supplementary power supplier and a winter clothes In this paper ZnO:Al thin film, which serves as a transparent conducting layer, was deposited on the polyethylene terephthalate(PET) substrate by the capacitively coupled r. f. magnetron sputtering method The effect of r. f. discharge power on the morphological, electrical and optical properties of ZnO:Al thin film were studied The film deposited on the PET substrate at r. f. discharge power of above 200 W and gas pressure of 5mTorr showed the minimum resistivity of about 2×10-3 Ω-cm, a transmittance of about 87% and optical band gap of 3.56 eV.

유도발전기로 연계된 풍력발전시스템의 시뮬레이터 개발 및 연계 특성분석

朴用熙,韓炳文 명지대학교 산업기술연구소 2007 産業技術硏究所論文集 Vol.26 No.-

This paper proposes a model for variable-speed wind turbine using the real wind data, and a reactive power compensator for the interconnected wind power system using a new 36-pulse voltage source converter. The propose wind turbine model was developed through more practical approach considering wind characteristic, blade characteristic and blade inertia compensation. The proposed reactive-power compensator was developed using a new 36-pulse voltage source converter with DC auxiliary circuit. The operational feasibility of proposed wind turbine and reactive-power compensator were verified by computer simulations with PSCAD/EMTDC and experimental works with 2kVA hardware model

응력-변형 거동 예측을 위한 탄소성 구성모델의 비교

문창열,박병수,조영묵 三陟大學校 1999 論文集 Vol.32 No.2

This paper is results of numerical analysis to investigate stress-strain behavior of sandy soils. Tree different constitutive relationships of Modified cam-Clay Model, Hyperbolic Model and Lade's Double-Work-Hardening Model were applied to predict stress-strain behavior of them. For each model, constitutive relations as well as parameters governing stress-strain behavior were programmed numerically. Weathered granite soil, tests were carried out with rich in Korea, and Ju Mun Jin Standard Sand were used as specimen of sandy soil. Stress-strain behaviors of these soils were obtained by performing isotropic compression and drained triaxial compression tests. For Weathered granite soil, tests were carried out with three different water contents determined on the basis of compaction test results. Four different relative densities were used with Ju Mun Jin Standard Sand. Numerically Predicted results with three different models were compared with tested results. Therefore applicability and problems of each model were discussed. Numerical analysis about sensitivity of parameters was also performed to investigate how these parameters influenced stress-strain behavior of sandy soils.

자동문을 위한 무선 안전 장치 시스템 및 중앙 통제 소프트웨어 개발

문병현,박종수,최상민,최용운,제정광 대구대학교 정보통신연구소 2004 情報通信硏究 Vol.3 No.2

본 논문에서 고급형 실내 자동문의 설계 및 제작한다. 실내에서 사용되는 특성에 따라 소음이 최소화되어야 하며 미세한 물건이나 어린이의 작은 신체 일부가 자동문에 끼이는 안전사고를 방지하기 위한 안전장치가 필수적이다. 따라서 본 시스템은 IrDA의 적외선 방식과 용량성 센서를 이용한 안전 장치 시스템을 설계하고 자동문을 가정용 컴퓨터를 이용하여 직접제어 하거나 외부에서 이더넷(Ethernet)으로 접속하여 제어 및 표시할 수 있는 프로그램을 개발한다. 또한 지능형 빌딩과 같이 다수의 자동창문을 화재, 강제 환기 및 기타 관리를 위한 중앙 통제 관리 시스템으로 확장된 중앙 통제 소프트웨어를 개발을 하였다. In this paper, the automatic door for indoor use is designed and developed. Since the door is used indoor, the noise should be minimized and the accident that can happen by small object and childrens fingers strapped by the door would be prevented. Thus, Safety module by using infrared is designed and the program that controls the door using ethernet is also developed. For the use of the large intelligent building, the program that can control the multiple doors is also developed.

PP/MMT 나노복합재료의 열안정성 및 기계적 계면 특성에 관한 연구

박수진,전병렬,송시용,이종문 한국공업화학회 2004 공업화학 Vol.15 No.1

본 연구에서는 몬모릴로나이트(Na^(-)-montmorillonite, MMT)를 dodecylammonium chloide로 유기적 개질하여 폴리프로필렌(PP) 나노복합재료의 열안정성과 기계적 계면 물성에 미치는 영향을 조사하였다. 나노복합재료의 구조 및 표면 특성은 각각 XRD와 FT-IR을 통해 알아보았고, 열안정성은 TGA를 통해 알아보았으며, 주조된 시편의 기계적 계면 물성은 K_(IC)와 G_(IC)를 통해 알아보았다. 실험 결과, dodecylammonium chloide을 이용한 MMT의 유기적 개질(DA-MMT)은 약 7.3 Å의 실리케이트 층간을 증가시켰고, DA-MMT 내의 CH_(2) 기에 의해 2800~2900 ㎝^(-1)에서 새로운 피크가 나타났다. PP/DA-MMT 나노복합재료의 열안정성은 순수한 PP 수지에 비해 향상되었는데, 이는 DA-MMT 입자와 PP 사이의 분자간 상호작용에 의한 것으로 판단된다. 또한, PP/DA-MMT 나노복합재료가 높은 기계적 계면 물성을 나타냈는데, 이러한 결과는 층간이 증가된 실리케이트에 PP가 쉽게 삽입되기 때문으로 판단된다. In this work. the effect of organic modification of Na-montmorillonite (MMT) with dodecylammonium chloride on thermal stabilities and mechanical interfacial properties of PP nanocomposites was investigated. The structure and surface properties of the nanocomposites were determined by XRD and FT-IR, respectively. The thermal stabilities of the nanocomposites were studied using a TGA analysis. Also, the mechanical interfacial properties were confirmed by KIC and GIC of casting specimens. As a result, the organic modification of MMT by dodecylammonium chloride(DA-MMT) led to the increase of the silicate layers to about 7.3 A, and the new peaks at 2800∼2900 cm^(-1) hand were shown in the presence of the CH groups on the DA-MMT. The thermal stahilities of PP/DA-MMT nanocomposites were higher than that of pure PP resin, which can be attributed to the increase of intermolecular interaction between DA-MMT particles and PP matrix. Also, the PP/DA-MMT nanocomposites had higher mechanical interfacial properties than those of pristime nanocomposites. These results explained that the pp was easily inserted in the spacing of the silcate interlayers of which were increased.