• 비파괴검사학회지
• /
• 제29권3호
• /
• pp.219-223
• /
• 2009

This paper prescribed the structural integrity of the API 5L X65 pipeline subjected to tensile pre-strain. The effects of pre-strain on the mechanical properties of API 5L X65 pipe were substantially investigated through a variety of the experimental procedures. Axial tensile pre-strain of 1.5, 5 and 10% was applied to plate-type tensile specimens cut from the pipe body prior to mechanical testing. Tensile test revealed that yield strength and tensile strength were increased with increasing tensile pre-strain. The increasing rate of the yield strength owing to the pre-strain is greater than that of the tensile strength. However, the pre-strain up to 5% had a little effect on the decreasing of the fracture toughness. The structural integrity of the API 5L X65 pipeline subjected to large plastic deformation was evaluated through the fitness-for service code.

• 해양환경안전학회지
• /
• 제25권3호
• /
• pp.395-403
• /
• 2019

This paper compares the marine engineering courses of two maritime institutions: Mokpo National Maritime University of Korea in the East Asia region and Philippine Merchant Marine Academy in the Southeast Asia region. It shows examines educational marine engineering programs, along with the different divisions and courses at each college. It demonstrates a divergence in methodologies and course offerings to cultivate competitive graduates. The comparative assessment completed is intended to offer broader knowledge on how each institution tackles the requirements of the STCW, and to meet the present and future demands of the maritime industry. Different course offerings are compared along with the units and hours allocated to each subject, and the differences in marine engineering academic and training requirements to graduate. Students must satisfactorily earn 150 units to complete their choice of major. Statistical procedures were used in this assessment and analysis from Excel programs.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.370-375
• /
• 1998

Spectral reflectance signatures of upland crops at OSMI bands were collected and evaluated for the feasibility of crop discrimination knowledge-based on crop calendar. Effective bands and their ratio values for discriminating corn from two other legumes were defined with OSMI equivalent bands and their ratio values. June 22 among measurements dates was the best date for corn discrimination from two other legumes, peanut and soybean, because all OSMI equivalent bands and their ratio values in June 22 were highly significant for corn separability. Phenological growth stage of a silage corn (rs510) could be estimated as a function of spectral reflectance signatures in vegetative stage. Five growth stage prediction models were generated by the SAS procedures REG and STEPWISE with OSMI equivalent bands and their ratio values in vegetative stage.

• Journal of Multimedia Information System
• /
• 제8권4호
• /
• pp.243-250
• /
• 2021

Instructional contents are used to demonstrate a technical process to teach and walkthrough certain procedures to carry out a task. This type of informational content is widely used for teaching and lectures in form of tutorial videos and training videos. Since there are questions and uncertainties for what could be the killer application for the novel wearables, we propose a self-instruction training application on a smart glass to utilize already-available instruction videos as well as public open data in creative ways. We design and implement a prototype application to help users train by wearing smart glasses specifically designed for two concrete and hand-constrained use cases where the user's hands need to be free to operate. To increase the efficiency and feasibility of the self-instruction training, we contribute to the development of a wearable killer application by integrating a voice-based user interface using speech recognizer, public open data APIs, and timestamp-based procedural content navigation structure into our proof-of-concept application.

• 한국통신학회논문지
• /
• 제34권11C호
• /
• pp.1076-1084
• /
• 2009

OFDM(Orthogonal Frequency Division Multiplexing) 전송 신호의 PAPR (Peak-to-Average Power Ratio)을 효과적으로 감소시키기 위하여 클리핑 잡음 (Clipping Noise)을 이용한 적응적 톤 삽입 (Adaptive Tone Injection; ATI) 기법을 제안한다. 제안된 ATI 기법은 기존 TI 방법에서의 복잡도 문제를 개선하기 위해, IFFT (Inverse Fast Fourier Transform) 출력 가운데 임계 진폭값 보다 큰 신호들을 클리핑 하는 과정, 클리핑된 신호에 대해 클리핑 잡음을 계산 후 주파수 영역 클리핑 잡음의 심벌 중에서 가장 큰 전력이 할당된 톤을 추출하는 과정, 추출된 톤을 확장된 성상도로 맵핑 후에 부분적으로 IFFT 하는 과정의 총 3단계로 구성된다. 모의실험 결과, 제안된 ATI 기법은 맵핑이 가능한 최적의 톤을 클리핑 잡음을 이용하여 추출함으로써 기존 TI 방법에서와는 달리 본래신호와 동일한 정보를 가지는 등가 신호의 가능한 모든 조합을 필요로 하지 않으며, OFDM PAPR 감소 성능 역시 최적의 TI 방법에 근접함을 보여준다.

• 한국전자통신학회논문지
• /
• 제14권5호
• /
• pp.817-824
• /
• 2019

OFDM(Orthogonal Frequency Division Multiplexing) 전송 신호의 PAPR (Peak-to-Average Power Ratio)을 효과적으로 감소시키기 위하여 클리핑 잡음 (Clipping Noise)을 이용한 적응적 톤 삽입 (Adaptive Tone Reservation; ATR) 기법을 제안한다. 제안된 ATR 기법은 기존 TR 방법에서의 복잡도 문제를 개선하기 위해, IFFT (Inverse Fast Fourier Transform) 출력 가운데 임계 진폭값 보다 큰 신호들을 클리핑 하는 과정, 클리핑된 신호에 대해 클리핑 잡음을 계산 후 주파수 영역 클리핑 잡음의 심벌 중에서 가장 큰 전력이 할당된 톤을 추출하는 과정, 추출된 톤을 예약하여 PAPR을 감소하는 과정의 총 3단계로 구성된다. 모의실험 결과, 제안된 ATR 기법은 톤 예약이 가능한 최적의 톤을 클리핑 잡음을 이용하여 추출함으로써 기존 TR 방법의 계산량을 획기적으로 줄이면서도 성능이 최적의 TR 방법에 근접한 것을 보여준다.

• Journal of Positioning, Navigation, and Timing
• /
• 제12권2호
• /
• pp.185-200
• /
• 2023

The Korea Augmentation Satellite System (KASS) is the first satellite navigation enhancement system in Korea developed in compliance with international standards. Technologies accumulated during the development process should be spread to industries such as academia and serve as the basis for developing the domestic satellite navigation field. This paper introduces the development process from design to implementation, testing, and verification of KASS control systems (KCS). First, development standards, milestones, requirements, and interface standards are presented as KCS development methods, and major functional design, physical design, and hardware/software implementation are described based on the allocated requirements. Subsequently, the verification environment, procedures, and results of the development product are covered and the developed operational and maintenance procedures are described. In addition, based on the experience gained through the development, suggestions were made for beneficial technology development and organization when promoting satellite navigation projects in the future. Since this work has important historical value for the development of domestic satellite navigation, it is expected that the development results will be shared with academia and industry in the future and be used as basic data for similar development.

• 대한원격탐사학회지
• /
• 제37권5_1호
• /
• pp.1149-1161
• /
• 2021

컴퓨터 비전 기술이 위성영상에 적용되면서, 최근 들어 딥러닝 영상인식을 이용한 구름 탐지가 관심을 끌고 있다. 본연구에서는 SPARCS (Spatial Procedures for Automated Removal of Cloud and Shadow) Cloud Dataset과 영상자료증대 기법을 활용하여 U-Net 구름탐지 모델링을 수행하고, 10폴드 교차검증을 통해 객관적인 정확도 평가를 수행하였다. 512×512 화소로 구성된 1800장의 학습자료에 대한 암맹평가 결과, Accuracy 0.821, Precision 0.847, Recall 0.821, F1-score 0.831, IoU (Intersection over Union) 0.723의 비교적 높은 정확도를 나타냈다. 그러나 구름그림자 중 14.5%, 구름 중 19.7% 정도가 땅으로 잘못 예측되기도 했는데, 이는 학습자료의 양과 질을 보다 더 향상시킴으로써 개선 가능할 것으로 보인다. 또한 최근 각광받고 있는 DeepLab V3+ 모델이나 NAS(Neural Architecture Search) 최적화 기법을 통해 차세대중형위성 1, 2, 4호 등의 구름탐지에 활용 가능할 것으로 기대한다.

• Tuberculosis and Respiratory Diseases
• /
• 제66권6호
• /
• pp.431-436
• /
• 2009

Background: In order to access the role of ballooning in patients with post-tuberculosis bronchial stenosis (PTBS), medical records of patients who underwent the procedure were reviewed. Methods: Twenty-nine PTBS patients underwent balloon dilatation between May 1999 and November 2000 at Samsung Medical Center. The median age was 28 (range 16~62 year) and most patients were female (n=27, 93%). The mean number of ballooning procedures was 2.4 (range 1~8) and the interval between ballooning procedures was 76.2$\pm$69.7 days. Results: In general, the $FEV_1$ was improved after ballooning (from 66.2.$\pm$11.9% predicted to 73.5$\pm$13.0% predicted, p=0.0004). Among 29 patients who underwent ballooning, a clinically successful outcome was observed in 16 patients (55%). Comparison between the successful and unsuccessful groups showed that favorable factors for a successful outcome were a higher pre-9ballooning $FEV_1$ (71.1$\pm$8.1 vs. 60.2$\pm$13.3% predicted), higher post-9ballooning $FEV_1$ (89.2$\pm$7.8 vs. 63.4$\pm$9.2% predicted) and absence of left upper lobe collapse. The clinical outcome was unsuccessful in all eight patients with a pre-9ballooning $FEV_1$ $\leq$57% of predicted or with complete left upper lobe collapse. Conclusion: In conclusion, ballooning appears to be helpful in patients with PTBS, especially when the pre-ballooning $FEV_1$ >57% of predicted and there is no complete left upper lobe lung collapse.

• 대한방사선기술학회지:방사선기술과학
• /
• 제39권3호
• /
• pp.323-328
• /
• 2016

두경부 질환의 인터벤션 시술 시 시술자가 받는 피폭선량의 평가 및 감소연구를 위한 선행 연구로써, 이온 전리함을 이용하여 인터벤션 시술 시 시술자의 위치하는 공간선량 분포를 측정하였다. Bi-plane 인터벤션 시술 장비를 대상으로 4개 구역(45, 135, 225 그리고 315도)으로 나누어 가상의 시술자가 있다는 가정아래에 시술자의 결정장기위치에서 거리(80, 100, 120, 그리고 140 cm)에 따라 조사선량을 측정하였으며, 방사선발생장치의 위치를 변화시켜 선량변화를 분석하였다. 시술자의 대부분이 위치하는 225도의 구역의 조사선량은 가장 가까운 거리인 80 cm에서 시술자 눈의 높이에서 114.5 mR/h, 가슴의 높이는 143.1 mR/h, 그리고 생식기위치는 147 mR/h이었다. 그리고 방사선 발생장치의 위치를 시술자 가까이로 변화시켰을 경우, 평균적으로 $18.1{\pm}10.5%$의 선량이 증가하였다. 본 연구에서 인터벤션 시술 동안 시술자가 위치할 수 있는 곳의 공간선량분포를 확인하였으며, 본 연구 결과를 통하여 시술자의 방사선 방어에 대하여 구체적인 계획을 수립할 수 있을 것이라 사료된다.