• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.105-114
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• 2003

It is conducted to analyze vibration loads on the 1st stage of KSR-III(KSR : Korea Sounding Rocket) during their ground transportation and various handling process. These loads may be different from the real flight environment. Inadequate assessment of these loads can cause not only local damages on the rocket system but also the critical problem like flight mission failure. Therefore, transportation and handling loads must be considered during design and attenuated to ensure that the rocket structural damage does not occur. This work is concerned with the generation of criteria and prediction of transportation and handling loads for KSR-III. The results show that the shipping container is well designed to satisfy the design requirements. The maximum vibration level recorded during whole transportation and handling for KSR-III is less than 2g, the criteria of KSR-III movement condition.

• Journal of Navigation and Port Research
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• v.38 no.6
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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.

• Journal of Navigation and Port Research
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• v.32 no.3
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• pp.207-213
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• 2008

Ship-handling simulation system has been used for maritime traffic safety assessment for harbor and fairway. There exist various environmental conditions under which ship may navigate along a fairway or in harbor. Due to the time and budget limitations, however, ship-handling simulations are usually carried out for very limited number of environmental conditions. In this paper, statistical method for effective and systematic determination of real time simulation conditions is suggested and applied to the maritime traffic safety assessment problems. In the empirical study, the principal component analysis method and the concept of empirical cumulative distribution function are suggested to estimate synthetic navigational difficulty and to select simulation conditions which would impose high difficulty on shiphandling.

• Fire Science and Engineering
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• v.28 no.1
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• pp.12-19
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• 2014

Workplaces handling hazardous chemicals are scattered, because of old-aging facilities are have been operating for more than 20 years, there is still has the risk of an accident. Advanced countries including the UN and strengthen regulation of chemicals, but the frequent leak accidents have become a big issue socially. In the case of subsequent domestic accidental chemical accident, the government and related departments for the overall prevention, preparedness, response system has been checked and improved. In this study, improvements of the related system and the plan of safety management for on the prevention of accidents and the initial response were suggested throughout the analysis of problems on the actual condition of safety management and such as standard of the related systems for handling, management for occurring the main cause of the leak and chemical accidents from hazardous chemicals handling in the workplace.

• Smart Structures and Systems
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• v.22 no.2
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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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• 1990.10a
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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.

• IE interfaces
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• v.13 no.4
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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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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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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• v.27 no.5
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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.

• Journal of the Korean Institute of Navigation
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• v.24 no.5
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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.