• 항공우주기술
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• 제2권2호
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• pp.105-114
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• 2003

본 논문에서는 KSR-III 1단부의 도로운송과 핸들링시에 예상되는 진동하중의 분석을 다룬다. 일반적으로 기체가 이송 중에 겪는 진동하중은 실제 기체가 비행 중에 겪는 진동 환경과는 많은 차이가 있다. 이송시 겪는 진동하중 특성에 대한 부적절한 해석은 이송 중에 로켓시스템에 직접적인 손상을 야기할 수 있을 뿐만 아니라, 비행임무 실패로 이어질 수도 있다. 그러므로, 기체 설계단계에서부터 이송시 진동하중을 함께 고려하여야 하며, 이송에 대한 적절한 방법을 강구해야 한다. 본 연구에서는, KSR-III의 도로운송이나 핸들링시의 진동하중을 예측하여 그 규격을 설정하는 과정을 기술하며, 저진동 이송치구의 동특성 분석과 사전도로테스트를 통하여 이송치구와 이송과정의 타당성을 검증하고, KSR-III 단인증 모델(1단)의 이송결과를 정리하고 분석한다. KSR-III 운송과정중의 최대허용 진동하중은 2g이며, 실제 운송결과 이보다 작은 값이 기록되었다.

• 한국항해항만학회지
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• 제38권6호
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• pp.689-694
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• 2014

The Korean government has introduced and enforced maritime traffic safety assessment to secure traffic safety since 2010. The maritime traffic safety assessment is needed by law to design a new port or modify an existing one. According to Korea Maritime Safety Act, in the assessment the propriety of marine traffic system consists of the safety of channel transit and berthing/unberthing maneuver, safety of mooring, and safety of marine traffic flow. The safety of channel transit and berthing/unberthing maneuver can be evaluated only by ship-handling simulation. The ship-handling simulation is carried out by sea pilots working with the port concerned. The vessel's proximity measure is an important factor to evaluate traffic safety. The proximity measure is composed of vessel's closest distance to channel boundary and probability of grounding/collision. What is more, the probability of grounding becomes important. According to central limit theorem, a sample has a normal distribution on condition that its size is more than 30. However, more than 30 simulation runs bring about the increase of assessment period and difficulty of employing sea pilots. Therefore this paper is to find out minimum sample size for evaluating vessel's proximity. First sample sets of size of 3, 5, 7, 9 etc. are selected randomly on the basis of normal distribution. And then KS test for goodness of fit and t-test for confidence interval are applied to each sample set. Finally this paper decides the minimum sample size. As a result this paper suggests the minimum sample size of 5, that is, the simulation of more than five times.

• 한국항해항만학회지
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• 제32권3호
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• pp.207-213
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• 2008

항만이나 항로에서의 심층적인 선박운항 안전성 평가를 위한 목적으로 주로 선박운항 시뮬레이션 시스템이 사용되고 있다. 하지만, 실제 해상에서 선박이 조우할 수 있는 환경 조건은 매우 다양한 반면, 비용이나 시간적인 제약으로 인하여 실시간 선박운항 시뮬레이션은 극히 한정된 경우에 대해서만 수행되는 것이 일반적이다. 본 논문에서는, 이러한 실시간 시뮬레이션 실험 조건을 효과적이고 체계적으로 도출하기 위한 통계적 기법에 대하여 제안하고, 이 기법을 실제 선박 운항 안전성 평가를 위한 시뮬레이션 연구에 적용한 실증 분석 결과를 사례 연구로 기술하였다. 실증 분석에는 주성분을 이용한 종합 운항 난이도 산정 방법과 누적 확률분포 개념을 이용하여 선박 운항 난이도가 높은 실험 조건을 실시간 시뮬레이션 실험 조건으로 선택하는 기법을 제시하였다.

• 한국화재소방학회논문지
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• 제28권1호
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• pp.12-19
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• 2014

유해화학물질 취급작업장은 전국적으로 산재되어 있고, 가동된 지 20년 이상 경과된 시설의 노후화로 사고의 위험이 상존하고 있다. UN을 비롯 선진국의 화학물질 규제는 강화되고 있지만, 누출사고는 빈번하게 발생되어 사회적 큰 이슈가 되고 있다. 최근 국내의 경우 잇따른 누출사고로 정부와 관련부처는 화학사고에 대한 전반적인 예방, 대비, 대응체계를 점검 및 개선하고 있다. 본 연구는 유해화학물질 취급작업장에서 발생되는 누출 및 화학사고의 주요 원인에 대한 안전관리 실태와 관련제도의 기준 등 취급, 관리상의 문제점을 분석하여 사고예방과 초기 대응을 위한 제도 및 안전관리 개선방안을 제시하였다.

• Smart Structures and Systems
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• 제22권2호
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• pp.231-237
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• 2018

A significant data problem is encountered with condition monitoring because the sensors need to measure vibration data at a continuous and sometimes high sampling rate. In this study, compressive sensing approaches for condition monitoring are proposed to demonstrate their efficiency in handling a large amount of data and to improve the damage detection capability of the current condition monitoring process. Compressive sensing is a novel sensing/sampling paradigm that takes much fewer data than traditional data sampling methods. This sensing paradigm is applied to condition monitoring with an improved machine learning algorithm in this study. For the experiments, a built-in rotating system was used, and all data were compressively sampled to obtain compressed data. The optimal signal features were then selected without the signal reconstruction process. For damage classification, we used the Variance Considered Machine, utilizing only the compressed data. The experimental results show that the proposed compressive sensing method could effectively improve the data processing speed and the accuracy of condition monitoring of rotating systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.170-174
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• 1990

The information with regard to the working range of lathe, cutting tool, cutting condition is managed as Database system for turning operation as one part of CAM system. Data with regard to the working range of lathe, cutting tool, cutting condition are stored by the DBMS(Data Base Management System) and can be added, modified, deleted and retrieved for realtime usages. Data stored in Database system are searched to select the most proper cutting tool and cutting condition with the input data fed from the design stage. Codes in regards to tool shape are displayed on graphic mode for easy selection for user and thus presents a good decision support for tool selection. The system developed in this work is operated by the pull down menu on the IBM PC/AT personal computer, or compatible series.

• 산업공학
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• 제13권4호
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• pp.646-657
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• 2000

We developed an efficient small sized weather condition forecasting system (WFS). A cheap NT-server was utilized for handling a large amount of data, while traditional WFS has conventionally relied on Unix based workstation server. The proposed WFS contains automatic weather observing system (AWS). AWS was designed for collecting weather conditions automatically, and it was linked to WFS in order to provide various weather condition information. The existing two phase scheme and chain code algorithm were used for transforming AWS's data into WFS's data. The WFS's data were mapped into geometric information system using various display techniques. Finally the transformed WFS's data was also converted into JPG (Joint Photographic Group) data type, and the final JPG data could be accessible by others though Internet. The developed system was implemented using WWW environment and has provided weather condition forecasting information. Real case is given to show the presented integrated WFS with detail information.

• 한국소음진동공학회논문집
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• 제26권6_spc호
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• pp.651-659
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• 2016

Condition monitoring (CM) encounters a large data problem due to sensors that measure vibration data with a continuous, and sometimes, high sampling rate. In this study, compressive sensing approaches for condition monitoring are proposed to demonstrate the efficiency in handling a large amount of data and to improve the damage detection capability of the current condition monitoring process. Compressive sensing is a novel sensing/sampling paradigm that takes much fewer samples compared to traditional sampling methods. For the experiments a built-in rotating system was used and all data were compressively sampled to obtain compressed data. Optimal signal features were then selected without the reconstruction process and were used to detect and classify damage. The experimental results show that the proposed method could improve the data processing speed and the accuracy of condition monitoring of rotating systems.

• The Journal of Korean Physical Therapy
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• 제27권5호
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• pp.364-368
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• 2015

Purpose: Walking in the dual-task condition is a critical skill for hemiplegic patients to live in real-life situations. The purpose of this study was to compare the effect of dual-task gait training and general gait training on gait parameters and cognitive function in patients with chronic stroke during dual-task walking. Methods: The study included 23 patients with chronic hemiparetic stroke who were randomly divided into experimental (dual-task gait training) and control (general walking training) groups. The 11 subjects in the experimental group and nine subjects in the control group received dual-task gait training (walking while handling a ball, crossing obstacles, picking up various objects, and problem solving simple cognitive tasks and general over-ground gait training, respectively, for 30 minutes per day 5 days per week for 4 weeks. Spatiotemporal parameters and cognitive tasks in the dual-task gait condition were measured. Statistical analysis of the changes between the pre- and post-intervention measurement variables was performed using ANCOVA. Results: In the gait condition under cognitive tasks, the changes pre- and post-intervention in gait velocity, stride length, double support limb, and step symmetry were significantly greater in the dual-task gait training group; however, the dual-task gait training group showed no significant improvement compared to the general gait training group in terms of the assessment of cognitive tasks. Conclusion: The findings suggest that dual-task gait training may be beneficial for walking ability in dual-task walking condition.

• 한국항해학회지
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• 제24권5호
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• pp.373-383
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• 2000

The ship’s safe mooring stability is a principles for the safe cargo handling works at the mooring berth. Today numerous standards, guidelines and recommendations concerning mooring practices, fittings and equipments exist throughout the worldwide maritime industries. In recently, the mooring facilities were constructed as dolphin types at the open sea area apart far from shoreside instead of enclosed coastline area in accordance with increasing ship’s size and for preventing environmental pollution. Therefore the exciting wave condition must be considered as a basic environmental criteria with the wind force and current force for all of the mooring ships at the sea berth facilities. In this study, this added wave force as one of the environmental external forces by using the theoretical formula was applied to the LNG ship in Pyeongtaeg harbor needed the special mooring stability of the sea berth. Through this research, it can be confirmed that wave force is the very important factor in the mooring force and the strength of wave force works much more in the full laden condition than in the lightship condition. And also the wave force changes to non-linear states according to the wave frequency and wave length. In addition, the maximum limit criteria of environmental force of prohibiting the entering ship on the berth and loading works controlled by the port authority concerned of Pyeongtaeg port fully satisfies the condition of the mooring limit force recommended by OCIMF that the safe permitted force of the mooring line have to be within 55 % of MBL.