• Journal of Ocean Engineering and Technology
• /
• v.23 no.1
• /
• pp.67-73
• /
• 2009

This study presents the results of a slamming experiment using a pneumatic cylinder. The employment of the pneumatic cylinder showed a relatively good repeatability when the results were compared with those of other slamming devices. The experiment was done for various incident angles. An air pocket was believed to cause a reduction in the magnitude of the impact pressure with an incident angle of $0^{\circ}$ for the water entry. A high speed camera was used in an attempt to locate the time of the contact between the bottom of the specimen and the free surface. It seemed that the maximum pressure occurred before the water contacted the bottom of the specimen.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.29 no.4
• /
• pp.134-141
• /
• 2021

As the domestic aviation industry grows, the aviation maintenance field is also growing rapidly. This change calls for more aircraft maintenance technicians, and interest in safety accidents is also increasing. Individual safety climate indicates the importance of safety in the organization. We expect that three individual factors (training effectiveness, procedure effectiveness, and work pressure) relate to safety behavior in the workplace via individual safety climate. The purpose of this research is investigating the relationship between individual factors and aircraft maintenance technician's safety behavior. Previous studies related to individual factors were examined for literature review. Based on the previous studies, research model was constructed. Hypothesis was verified by effected data from 305 samples were employed for final survey. The results show that individual factors were meaningful factors to effect perceived safety behavior, and safety knowledge & safety motivation were related to safety compliance & safety participation.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.1195-1198
• /
• 2008

본 논문은 다중 Tier 상에서 온라인 서비스 대량 데이타 처리를 빠르고 정확하게 클라이언트에 전달하는 기법을 제안한다. Tier 가 많은 온라인 서비스상에서 대량의 데이타를 빠르게 처리하는 데에는 많은 어려움이 있다. Tier 간 지연 시간의 최소화, 네트워크 대역폭를 고려한 트란잭션(Transaction)의 적절한 분할 통신, 이 기종간의 데이타 변환 시 처리속도 개선 등이 해결해야 할 주요한 요건이라고 할 수 있다. 하지만 이러한 문제들이 해결된다고 해서 괄목할 만한 성능의 개선은 쉽게 나타나지 않는다. 그 이유는 바로 Partial Query에 의한 데이타 통신이 꾸준히 반복 발생하기 때문이다. 온라인 서비스의 특성상 대량 데이타는 많은 사용자의 효율적인 트란잭션 처리를 위하여 분할(Partial) 처리되어 통신하는 방식을 기준으로 사용하고 있다. 이러한 방식을 준수 하기 위해서는 데이타 사이즈에 비례하는 반복의 증가가 불가피하다. 그래서 반복 횟수를 줄이는데 포커스를 두고 온라인 서비스 대량 데이타 처리에 대한 성능 데스트를 진행한 결과 반복이 최소화 될수록 성능은 최대한으로 유지되며, 다른 어떤 기술적인 요소를 개선하는 것보다 큰 효과를 볼 수 있음을 알 수 있었다.

• Journal of Internet Computing and Services
• /
• v.23 no.3
• /
• pp.47-56
• /
• 2022

The safe driving reward system aims to reduce the loss of life and property by reducing the occurrence of accidents by motivating safe driving and encouraging active participation by providing direct reward to vehicle drivers who have performed safe driving. In the case of the existing digital tachograph, the goal is to limit dangerous driving by recording the driving status of the vehicle whereas the safe driving reward system is a support measure to increase the effect of accident prevention and induces safe driving with financial reward when safe driving is performed. In other words, in an area where accidents due to speeding are high, direct reward is provided to motivate safe driving to prevent traffic accidents when safe driving instructions such as speed compliance, maintaining distance between vehicles, and driving in designated lanes are performed. Since these safe operation data and reward histories must be managed transparently and safely, the reward evidences and histories were constructed using the closed blockchain Hyperledger Fabric. However, while transparency and safety are guaranteed in the blockchain system, low data processing speed is a problem. In this study, the sequential block generation speed was as low as 10 TPS(transaction per second), and as a result of applying the acceleration function a high-performance network of 1,000 TPS or more was implemented.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.30 no.4
• /
• pp.105-116
• /
• 2022

Domestic and foreign aviation industries showed steep growth along with rapid increase in aviation demand, but the industries got directly hit by COVID-19. Now, with the recovery of daily life, aviation demand is gradually increasing, too. However, the risk of aviation accidents also increases proportionally to the increasing demand for aviation. Although it is a point that safety management needs to be actively conducted to prevent safety accidents resulted from the growth of aviation industries, research on safety culture and organizations is not sufficiently done in terms of the depth and scope of it despite the importance of the discussion. Studies in various areas have reported that an organization's safety culture forms the group's safety atmosphere and then results in the workers' safety behavior. Accordingly, this study examined the effects of safety culture in an organization on the safety behavior of its members who are aircraft maintenance technicians. The results of this research can be summed up as follows: first, it has been found that the roles of the person in charge grounded on clear goals and guidelines for the organization's safety policy influence the technicians' attitudes. Second, the important factor in the technicians' safety observance is that the attitude to follow safety rules when performing aviation maintenance raises their awareness of safety, for instance, following standard operation procedures or wearing personal equipment for protection. Third, their attitudes have positive effects on safety participation, and consequently, their intention to comply with safety rules is shown as an active action to achieve the ultimate goal of safety behavior.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.6
• /
• pp.21-30
• /
• 2022

This paper describes the design, manufacture, and testing of servos applicable to small tracking radars. First, Chapter 1 describes the necessity of this study. Chapter 2 describes the development of servos applicable to future tracking radars in small missile systems. Chapter 3 describes the design and test results for current control of brushed DC motors, brushless DC motors, and permanent magnet synchronous motors. And Chapter 4 describes the design and test results for speed control of the test wheel. And in Chapter 5, the results of the previous tests are summarized. In this paper, some pictures were intentionally blurred for security reasons, and the control result of test wheel was described, not the test with the developed gimbals.

• Journal of Korea Technology Innovation Society
• /
• v.17 no.4
• /
• pp.733-762
• /
• 2014

The government mandates that national research facilities & equipments through R&D business budget should be registered on the National Science and Technology Information Service (NTIS) for the purpose of the efficient use of the research facilities & equipments. This study is to contribute to the national policies on the efficient management of the research facilities & equipments by recognition methodology with the university's members and analysis of the impact factors of the universities' registration process improvement through the Define level and Measure level of the Six Sigma DAMIC. The survey and interview were conducted on research directors, professors joining university administration, graduate students, researchers, and staffs of A University. The findings are the lack of understanding specific steps and life-cycle management of research facilities & equipments. It is necessary to collect suggestions from universities and pursue policies considered the unique characteristics of the university for advanced operating and maximizing use of university's national research facilities & equipments. Research facilities & equipments enrollment compliance rate and registration accuracy were selected as CTQ-Y through the Six Sigma. 72 potential cause variables were derived through Process Map and C & E Diagram. 13 variables were determined as core potential factors through the X-Y Matrix and Pareto Chart. Research institutions should maximize utilization of research facilities & equipments through deriving a potential variables of the process improvements and designing a detail improvements based on the characteristics of each institutions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.99-103
• /
• 2017

As a development test of the 75-tonf LOx/Kerosene liquid rocket engine for KSLV-II first Stage Engine, hot firing test of 75-tonf engine are performed. The current status of development test on first stage 75-tonf engine system including combustion chamber, turbopump, gas generator, propellant supply system are presented. During the 75tonf engine test campaign, the development of startup sequence of LOx-Kerosene engine system, engine startup using pyrostarter, ignition of gas generator, steady operation and engine shutdown is successfully performed. As a passenger test during engine hot firing tests, Thrust Vector Control system (TVC) of the engine are also evaluated during engine hot firing test. The results of hot firing test of 75-tonf thrust engine system will be used for the design confirmation and performance evaluation of 75 tonf engine system for KSLV-II first Stage.

• Journal of KIISE:Software and Applications
• /
• v.34 no.7
• /
• pp.635-645
• /
• 2007

Component technology has been widely accepted as an effective way for building software systems with reusable components, and Microsoft (MS) .NET is one of the recent representative component technologies. Model Driven Architecture (MDA) is a new development paradigm which generates software by transforming design models automatically and incrementally. Transformation of structural models in MDA has been successfully applied. However, transformation of dynamic models and pervasive services, such as transaction service, security service, synchronization service and object pooling are largely remains as an area for further research. The recent enterprise system has multi tier distributed architecture, and the functionality of early mentioned pervasive services is essential for this architecture. .NET platform can implement Component Object Model+ (COM+) component for supporting pervasive services by specify Attribute code. In this paper, we specify the functionalities of the COM+ component offering pervasive services, and then those functionalities are defined by UML profile. By using the profile, the Platform Specific Model (PSM) for .NET/C# is specified, and .NET components are automatically generated through our tool. The development productivity, extensibility, portability, and maintenance of software can be dramatically improved by using of the proposed methods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.582-590
• /
• 2016

The purpose of this study is to investigate the relationship between suicidal attitude and suicidal ideation of college students and also to provide the fundamental data in order to strengthen both the standard and the recommendation of media coverage in Korea. A total of 249 college students over the age of 18 years in B city and G do were enrolled for this study. The data were collected between June 9 and July 7 of 2014 and analyzed by using descriptive statistics, t-test, ANOVA, Pearson correlation coefficients, and multiple regression with SPSS 21.0. The mean score of a message of suicidal motivation reports 2 was $51.06{\pm}10.55$, which was the highest. The score of suicidal ideation was $10.41{\pm}12.88$. There were sign&ificant differences in suicidal thought with respect to school system, family income, pocket money, time of physical activity, smoking, and smart-phone usage in university students. It was shown that suicidal thoughts were significantly correlated with message of simple suicidal reports 1(r=.303, p<.001), message of suicidal motivation reports 2(r=.251, p<.001), and message of suicidal mourning man reports 3(r=.225, p<.001). As the suicidal attitude have a close association with reports of suicide, it is necessary that studies on a variety of factors influencing suicidal thoughts of students be repeated.