• 대한조선학회논문집
• /
• 제53권2호
• /
• pp.85-91
• /
• 2016

The most important factor in the structural design of ships and offshore structures operating in arctic region is ice load, which results from ice-structure interaction during the ice collision process. The mechanical properties of ice related to strength and failure, however, show very complicated aspect varying with temperature, volume fraction of brine, grain size, strain rate and etc. So it is nearly impossible to establish a perfect material model of ice satisfying all the mechanical characteristics completely. Therefore, in general, ice collision analysis was carried out by relatively simple material models considering only specific aspects of mechanical characteristics of ice and it would be the most significant cause of inevitable errors in the analysis. Especially, it is well-known that the most distinctive mechanical property of ice is high dependency on strain rate. Ice shows brittle attribute in higher strain rate while it becomes ductile in lower strain rate range. In this study, the simulation method of ice collision to ship hull using the nonlinear dynamic FE analysis was dealt with. To consider the strain rate effects of ice during ice-structural interaction, strain rate dependent constitutive model in which yield stress and hardening behaviors vary with strain rate was adopted. To reduce the huge amount of computing time, the modeling range of ice and ship structure were restricted to the confined region of interest. Under the various scenario of ice-ship hull collision, the structural behavior of hull panels and failure modes of ice were examined by nonlinear FE analysis technique.

• 정신신체의학
• /
• 제24권1호
• /
• pp.61-65
• /
• 2016

다양한 정보통신기술(Information & Communication Technology, ICT)들이 정신건강 영역에서 성공적으로 활용되고 있다. 특히 모바일 애플리케이션은 효과적인 ICT 중 하나이며, 스마트폰이 널리 보급된 이후 여러 앱들이 개발되고 있다. 모바일 기반 정신건강 개입은 치료 접근성 향상, 실시간 모니터링을 통한 증상 및 일상 활동의 손쉬운 확인과 같은 여러 장점이 있다. 치료 경과에서의 더 나은 추적 관찰, 개별화된 피드백과 향상된 이동성으로 인하여 환자들의 순응도를 향상시킬 수도 있다. 하지만 정신건강과 관련된 모바일 기술에는 전기통신 오류, 데이터 안전성 문제, 개인 정보 유출 같은 기술적인 애로사항들이 제한점으로 존재한다. 따라서 기술의 개발과 제공 과정에서 이에 대한 충분한 고려가 필요하다. 무엇보다도 정신건강 전문가들이 근거에 기반을 둔 경험들을 결합하고, 양질의 임상적 수준을 보장하면서 개발과정에 적극적으로 참여해야 할 것이다.

• Human Ecology Research
• /
• 제57권1호
• /
• pp.91-107
• /
• 2019

The use of standardized stitches in globalized apparel markets is becoming increasingly important. However, many apparel vendors still use disunified stitches, such as Japanese and English. This study analyzes the usage of clothing stitches of cut and sewn knit garment fabrication of small companies. The results of the analysis of 464 worksheets of cut and sewn knit garments are as follows. First, of the 464 worksheets, only 4.31% are labeled as ISO 4915 No. Among the 1,399 stitches, only 3.15% were marked with the ISO 4915 No. Second, among 1,399 stitches, ISO 4915 No. 406 followed by 401 was the most frequently used. Third, in the case of the top, ISO 4915 No. 406 was used the most; in addition, ISO 4915 No. 401, 301 and 304 were also frequently used. Fourth, in the case of the bottoms, the stitch with the highest frequency was ISO 4915 No. 406 followed by ISO 4915 No. 103 and 401, respectively. Fifth, in the case of the top, ISO 4915 No. 406 was most commonly used in hemlines and sleeve edges; in addition, in the case of the bottoms, ISO 4915 No. 406 and 103 were most commonly used as hemlines. In conclusion, it is important to use international standard stitches, especially for the most frequently used stitches. By using the standard stitches, the communication errors between production departments can be reduced and information can be accurately delivered.

• Nuclear Engineering and Technology
• /
• 제51권6호
• /
• pp.1696-1707
• /
• 2019

This paper conducts a qualitative policy analysis of current challenges to safety culture and security culture in Southeast Asia and emerging best practices in Northeast Asia that are aimed at strengthening both cultures. It analyses lessons, including strengths and limitations, that can be derived from Northeast Asian states, given the long history of nuclear energy in South Korea, China and Japan. It identifies and examines best practices from Northeast Asia's Nuclear Security Centres of Excellence in terms of boosting nuclear security culture and their relevance for Southeast Asia. The paper accentuates the important role of the State in adopting policy and regulatory frameworks and in institutionalising nuclear education and training programmes to deepen the safety-security cultures. Best practices in and challenges to developing a nuclear safety culture and a security culture in East Asia are examined using three frameworks of analysis (i) a comprehensive nuclear policy framework; (ii) a proactive and independent regulatory body; and (iii) holistic nuclear education and training programmes. The paper argues that Southeast Asian states interested in harnessing nuclear energy and/or utilising radioactive sources for non-power applications must develop a comprehensive policy framework on developing safety and security cultures, a proactive regulatory body, and holistic nuclear training programmes that cover both technical and human factors. Such measures are crucial in order to mitigate human errors that may lead to radiological accidents and nuclear security crises. Key lessons from Japan, South Korea and China such as best practices and challenges can inform policy recommendations for Southeast Asia in enhancing safety-security cultures.

• 응용통계연구
• /
• 제32권3호
• /
• pp.391-404
• /
• 2019

그동안의 고객 행동에 대한 예측은 주로 고객이 가지는 고정적인 특성을 이용해왔다. 최근에는 점차 고객들의 활동이 오프라인에서 온라인으로 이동하면서 각 고객의 웹 로그를 추적하는 일이 가능해졌다. 그러나 방대한 양의 웹 로그 데이터를 수집할 수 있게 된 반면, 이에 대한 연구는 로그 데이터를 정리하거나 기술적인 특성만을 설명하는 것에 그쳤다. 본 연구에서는 웹사이트 Kaggle에서 제공하는 Airbnb 고객들의 성별, 연령 등의 기본 정보 및 웹 로그가 포함된 데이터셋을 이용하여 첫 숙소 예약까지 걸리는 개인의 의사 결정 시간을 예측하였다. Lasso, SVM, Random Forest, XGBoost 등 다양한 방법론을 활용하여 최적의 모형을 찾고, 웹 로그 데이터의 유무에 따른 예측 오차를 비교하여 웹 로그의 효용성을 확인하였다. 결과적으로 오분류율이 약 20%로 낮은 랜덤 포레스트 분류모형을 최적모형으로 선택하였다. 또한, 웹 로그 데이터를 이용하여 고객 개개인의 행동을 예측한 결과 사용하지 않은 경우와 비교해 예측의 정확도가 최대 두 배 더 높아진 것을 확인할 수 있었다.

• 한국항행학회논문지
• /
• 제22권2호
• /
• pp.133-140
• /
• 2018

최근 항공전자시스템 개발에서 비용절감 및 안전인증을 지원하는 방법의 하나로 모델 기반 설계 기법을 사용한다. 모델 기반 설계를 이용하여 항공기 및 항공전자 장비 (아이템)의 성능 분석 및 안전성 분석을 지원하기 위하여 이종의 시뮬레이터를 연동하는 멀티 도메인 시뮬레이션 환경을 개발하였다. 대기 자료 컴퓨터와 통합 다기능 프로브를 항공기 수준에서 검증 할 수 있는 멀티 도메인 시뮬레이션 환경을 제시한다. 모델은 Simulink로 개발하였고, 항공기 수준에서 모델을 검증하기 위해서 비행시뮬레이터인 X-Plane 10을 사용하였다. 항공전자 시스템 모델기능을 항공기 수준에서 시험하였고, 모델과 비행시뮬레이터의 대기 자료 오차는 0.1%이내로 측정 되었다.

• 한국안전학회지
• /
• 제36권3호
• /
• pp.74-80
• /
• 2021

Korea Atomic Energy Research Institute (KAERI) has been operating an integral effects test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), according to APR1400 for transient experimental and design basis accident simulation. Moreover, based on the experimental data, the domestic standard problem (DSP) program has been conducted in Korea to validate system codes. Recently, through DSP-05, the performance of the passive auxiliary feedwater system (PAFS) in the event of multiple steam generator tube rupture (MSGTR) has been analyzed. However, some errors exist in the reference input model distributed for DSP-05. Furthermore, the calculation results of the heat loss correlation for the secondary system presented in the technical report of the reference indicate that a large difference is present in heat loss from the target value. Thus, in this study, the reference model is corrected using the geometric information from the design report and drawings of ATLAS. Additionally, a new heat loss correlation is suggested by fitting the results of the heat loss tests. Herein, MSGTR-PAFS accident analysis is performed using MARS-KS 1.5 with the improved model. The steady-state calculation results do not significantly differ from the experimental values, and the overall physical behavior of the transient state is properly predicted. Particularly, the predicted operating time of PAFS is similar to the experimental results obtained by the modified model. Furthermore, the operating time of PAFS varies according to the heat loss of the secondary system, and the sensitivity analysis results for the heat loss of the secondary system are presented.

• International Journal of Computer Science & Network Security
• /
• 제21권6호
• /
• pp.23-28
• /
• 2021

The article discusses the features of adaptation of the parameters of the physical layer of data transmission in self-organizing networks based on unmanned aerial vehicles operating in the conditions of "smart cities". The concept of cities of this type is defined, the historical path of formation, the current state and prospects for further development in the aspect of transition to "smart cities" of the third generation are shown. Cities of this type are aimed at providing more comfortable and safe living conditions for citizens and autonomous automated work of all components of the urban economy. The perspective of the development of urban mobile automated technical means of infocommunications is shown, one of the leading directions of which is the creation and active use of wireless self-organizing networks based on unmanned aerial vehicles. The advantages of using small-sized unmanned aerial vehicles for organizing networks of this type are considered, as well as the range of tasks to be solved in the conditions of modern "smart cities". It is shown that for the transition to self-organizing networks in the conditions of "smart cities" of the third generation, it is necessary to ensure the adaptation of various levels of OSI network models to dynamically changing operating conditions, which is especially important for the physical layer. To maintain an acceptable level of the value of the bit error probability when transmitting command and telemetry data, it is proposed to adaptively change the coding rate depending on the signal-to-noise ratio at the receiver input (or on the number of channel decoder errors), and when transmitting payload data, it is also proposed to adaptively change the coding rate together with the choice of modulation methods that differ in energy and spectral efficiency. As options for the practical implementation of these solutions, it is proposed to use an approach based on the principles of neuro-fuzzy control, for which examples of determining the boundaries of theoretically achievable efficiency are given.

• 한국건축시공학회지
• /
• 제21권4호
• /
• pp.377-386
• /
• 2021

본 연구는 지난 2019년 4월에 대한건축학회 기술표준(AIK-S-001-2019)으로 제정된 복합열화 및 구조체 거동이 동시에 작용하는 환경에서의 방수층 성능 시험방법에 있어 일부 표준 내용 중 현장 시공성 반영 부족 문제와 표준 시공 방법으로서 오류 부분 등이 지적되면서 이를 보완해야 한다는 관련 업계, 시공사, 발주자(건설사) 등에서 의견이 제안되었다. 이에 본 연구를 통하여 시험 항목인 구조물 거동대응성능 시험방법에 있어 현장 시공성, 시험 결과의 정량화, 기타 개선 사항 등을 고찰하였다. 고찰된 내용을 이용하여 표준(안)으로 제정 중인 (가칭)점착형 복합 방수시트에 포함되어 진행하고 있는 구조물거동대응성능 시험방법에 표준 규격으로서 활용 가능성과 현장 시공성 반영 문제 등의 개선 내용을 검토하였다. 또한, 검토된 내용을 반영하여 1차와 2차 성능평가를 실시하여 그 결과를 도출하였다. 이에 본 연구를 통하여 도출된 개선(안) 및 성능평가 결과를 토대로 (가칭) 점착형 복합방수시트 제정(안)의 기초 자료로 활용하고자 한다.

• Nuclear Engineering and Technology
• /
• 제54권7호
• /
• pp.2444-2452
• /
• 2022

The field-programmable gate array (FPGA) is gaining popularity in industrial automation such as nuclear power plant instrumentation and control (I&C) systems due to the benefits of having non-existence of operating system, minimum software errors, and minimum common reason failures. Separate functions can be processed individually and in parallel on the same integrated circuit using FPGAs in comparison to the conventional microprocessor-based systems used in any plant operations. The use of FPGAs offers the potential to minimize complexity and the accompanying difficulty of securing regulatory approval, as well as provide superior protection against obsolescence. Wireless sensor networks (WSNs) are a new technology for acquiring and processing plant data wirelessly in which sensor nodes are configured for real-time signal processing, data acquisition, and monitoring. ZigBee (IEEE 802.15.4) is an open worldwide standard for minimum power, low-cost machine-to-machine (M2M), and internet of things (IoT) enabled wireless network communication. It is always a challenge to follow the specific topology when different Zigbee nodes are placed in a large network such as a plant. The research article focuses on the hardware chip design of different topological structures supported by ZigBee that can be used for monitoring and controlling the different operations of the plant and evaluates the performance in Vitex-5 FPGA hardware. The research work presents a strategy for configuring FPGA with ZigBee sensor nodes when communicating in a large area such as an industrial plant for real-time monitoring.