http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Compact Dipole Antenna for Terrestrial Digital Multimedia Broadcasting Service
Kwangwoo Ryu,Seunggil Jeon,김정표,최재훈 한국전자통신연구원 2008 ETRI Journal Vol.30 No.3
A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed.
Kwangwoo Cho,Junha Choi,Changdeok Ko,Muhyun Kim,Joohan Lee,Eunhyang Eom,Sung-Hak Cho 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.2
Glass is widely used for various applications, including flat panel displays, solar panels, architectural windows, and exterior materials. These applications exhibit increasing complexity and improved functionality. In particular, glass substrates used in display panels require diverse forms of processing, prompting the exploration of laser applications to enhance processing quality, yield, and efficiency. This study aims to investigate the feasibility of using a high absorption, 257 nm femtosecond laser for processing glass substrates. The goal is to minimize damage and eliminate the need for post-processing, and ensuring superior quality and cross-sectional features. The analysis focuses on the influence of energy density and laser beam overlap ratio on processing variations. Point, line, and area processing were conducted within the achievable energy density range of 2.4–10.8 J/cm2. The results indicate that as the overlap ratio increases, processing depth, influenced by heat accumulation, exhibits a non-linear growth pattern. Moreover, the phenomenon of excessive processing width, surpassing design specifications, is mitigated by utilizing burst pulses that induce heat accumulation of ultra-short pulse lasers, thereby promoting increased processing depth while restraining width expansion. By comparing the outcomes of glass substrate processing using different laser wavelengths and pulse durations, it is confirmed that employing a 257 nm femtosecond laser minimizes damage, cracks, and chipping in the processed areas, obviating the need for post-processing. This paper presents the pioneering research on glass processing using deep ultraviolet femtosecond lasers. Results indicate that clear glass ablation is achieved without cracks.
Risk factors of advanced metachronous neoplasms in surveillance after colon cancer resection
( Kwangwoo Nam ),( Jeong Eun Shin ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.2
Background/Aims: Regular surveillance colonoscopy after colon cancer resection is recommended for detecting metachronous adenoma and cancer. However, risk factors for metachronous neoplasms have not been fully evaluated. We aimed to assess risk factors for advanced metachronous neoplasms during surveillance colonoscopy after colon cancer resection. Methods: Patients who underwent curative colectomy for nonmetastatic colon cancer between January 2002 and December 2012 were evaluated and followed up to December 2017. Results: A total of 293 patients were enrolled in this study. Among these, 179 (61.1%) were male, and the mean age was 63.2 ± 10.4 years. On perioperative clearing colonoscopy, synchronous high-risk adenomas (number ≥ 3, size ≥ 10 mm, high-grade dysplasia, villous histology, and serrated adenoma ≥ 10 mm) were detected in 95 patients (32.4%), and they were significantly associated with male sex, old age (≥ 65 years), current alcohol consumption, and current smoking (p < 0.05). During the follow-up period (mean 74.4 ± 36.4 months), advanced metachronous neoplasms were found in 45 patients (15.4%), including metachronous cancer in four (1.4%). In multivariate analysis, distal colon cancer (distal-to-splenic flexure; odds ratio [OR], 4.402; 95% confidence interval [CI], 1.658 to 11.689; p = 0.003), synchronous high-risk adenomas (OR, 3.225; 95% CI, 1.503 to 6.918; p = 0.003), and hypertension (OR, 2.270; 95% CI, 1.058 to 4.874; p = 0.035) were significant risk factors for advanced metachronous neoplasms. Conclusions: During surveillance after curative colon cancer resection, patients with distal colon cancer, synchronous high-risk adenomas, and hypertension may need meticulous follow-up to improve overall outcomes.
돔 분리형 연소관의 접착 길이에 따른 체결부의 구조해석
전광우(KwangWoo Jeon),신광복(KwangBok Shin),황태경(TeaKyung Hwang) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.11
돔 분리형 복합재 연소관의 접합 체결부 최적의 설계 길이를 결정하기 위해 접합부 길이변화에 따른 구조해석을 수행하였다. 이때, 접착 체결부의 길이는 50mm에서 300mm의 범위를 갖는다. 무응력 상태의 초기 접합부 길이대비 응력구배가 발생하는 구간의 길이를 “응력구배 길이 비”로 정의하고 이를 목적함수로 선정하였다. 구조해석 결과 접착 체결부의 길이가 200mm 이상으로 증가할 경우 응력구배 길이 비의 증가가 서서히 나타남을 확인하였다. 이는, 접착 체결부에 적용되는 2,500psi 내압에서 구조적 안전성을 확보하는 최적화된 접착 체결부의 길이가 200mm임을 의미한다. In order to determine optimal design length of adhesive joint of a composite pressure vessel with separated dome, stress analysis of joint part according to changes of adhesive length was done. Adhesive length has a range of 50mm to 300mm as design variables. The ratio of adhesive length with any stress gradient to initial non-stressed adhesive length was called "stress gradient length ratio" and selected as objective function. The stress gradient length ratio of joint part with adhesive length of more than 200mm was increased very slowly with increase of adhesive length. It means that adhesive length of about 200mm could be the optimal value to ensure the structural safety of joint part against internal pressure of 2,500 psi.
이광우(Kwangwoo Lee),김승주(Seungjoo Kim),원동호(Dongho Won) 한국정보보호학회 2011 情報保護學會誌 Vol.21 No.3
최근 스마트폰, 스마트 TV 등의 스마트 기기의 도입에 따른 스마트 서비스의 등장은 기존의 방송, 통신, 교통, 업무환경을 계속 변화시키고 있다. 즉, 기존과 달리 스마트 서비스 환경에서는 스마트 기기들이 곳곳에 배치되어 유?무선 네트워크를 통해 정보를 주고받으며, 각종 서비스를 제공한다. 따라서 스마트 기기들 간의 통신은 기존 ICT(Information and Communication Technology) 시스템과 동일하게 전송 데이터를 보호하기 위한 보안 기술이 요구된다. 특히 스마트워크에서는 시간과 장소에 국한되지 않고 언제 어디서든 효율적인 업무 수행이 가능하도록 스마트폰 및 태블릿 PC와 같은 모바일 기기를 이용하게 된다. 이러한 상황에서는 여러 공간에서 업무가 이루어질 수 있으며, 프린팅 역시 다양한 네트워크 환경에서 이루어질 수 있다. 이에 본 논문에서는 업무 공간의 다양성과 모바일 기기의 도입에 따른 프린팅 서비스 기술의 발전 및 개발 현황을 살펴보고, 안전한 프린팅과 관련하여 진행되고 있는 표준화 동향을 살펴보고자 한다.