• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.463-468
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• 2011

The prospect of Arctic trade transportation opening on a year-round basis creates a vast opportunity of exploring untapped resources and shortened navigational routes. However, the environment's remoteness and lack of technical experiences remains a big challenge for the maritime industry. With this, engine designers and makers are continually investigating, specifically optimizing propulsion shafting system design, to meet the environmental and technical challenges of the region. Further, classification societies recognize the need to upgrade the Unified Rules concerning elements to meet current Polar requirements. Hence in this paper, excitation torque calculation on Polar class vessels propulsion shafting system will be reviewed. The propeller - ice interaction load effect, which is a main consideration of excitation source of Polar Class propulsion shafting system, on shaft design calculation will be analyzed.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.141-143
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• 1994

The pulse width modulated class D power amplifier has the highest efficiency among various class amplifiers but the performances, such as bandwidth, distortion and stability are inferior to the conventional ones. In this paper, a new class D amplifier design is Presented employing dual feedback loops namely current and voltage feedback. The new design provides wide full-power bandwidth and stability at any load with high efficiency.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.183-183
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• 2012

As as result of development of new voyage route, especially Baltic seas, it is necessary for the design to meet ice class requirements as vessels continue to increase in this route. For this reason Finish-Swedish ice class has recently amended a regulation on the propulsion shafting design and engine output required for the ships which will be navigable in the brash ice channels broken by ice-breakers in Baltic seas. Therefore, this study shows the appropriate calculation methods for the design of engine output and propulsion shafting system based on ice class requirements.

• Korean Journal of Computational Design and Engineering
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• v.13 no.3
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• pp.187-199
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• 2008

This paper describes a C++ class hierarchy of implicit objects for geometry modeling and processing. This class structure provides a software kernel for integrating many various models and methods found in current implicit modeling areas. The software kernel includes primitive objects playing a role of unit element in creating a complex shape, and operator objects used to construct more complex shape of implicit object formed with the primitive objects and other operators. In this paper, class descriptions of these objects are provided to better understand the details of the algorithm or implementation, and its instance examples to show the capabilities of the object classes for constructive shape geometry. In addition, solid modeling system shown as an application example demonstrates that the proposed implicit object classes allow us to carry out modern solid modeling techniques, which means they have the capabilities to extend to various applications.

• Journal of Engineering Education Research
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• v.21 no.4
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• pp.28-34
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• 2018

Design class through team activities is increasing in engineering education. Team-based education has been known to improve students' creativity, problem solving ability, cooperative ability, self-directed learning ability, and communication ability. How to organize a team is an important issue that affects the performance of team activities as well as student satisfaction. However, previous studies have focused on the causal relationship between team formation and the team's performance. This paper deals with how to organize a balanced team in a real class. When the basic characteristic values of students are givens, the aim is to make the sum of the characteristic values as fair as possible for each team. We propose a mathematical team formation model and show how to apply it through case studies.

• Journal of Engineering Education Research
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• v.13 no.2
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• pp.16-21
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• 2010

The objective of this study was to evaluate Environmental microbiology (EM) as a basic course for the environmental engineering program of Korea Maritime University which has been accredited by Accreditation Board for Engineering Education of Korea (ABEEK). Evaluation result of the lecture objectives was more than the average (3.5/5.0). The overall score for learning achievement assessment was more than average level of learning achievement (3.4/5.0). Interestingly, engineering design implementation regarding a specific topic as an extensive learning process has proven to be more effective (3.5/5.0). Some of effective class improvement strategies suggested were to encourage students to participate in the class with self-motivation and accountability: preview and review of the lecture, team presentation in English-speaking settings, and submitting project report written in English. In the future class of EM, test and evaluation of application capability of EM and environmental biotechnology (EB) theories to engineering problem solving should be emphasized.

• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.143-149
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• 2016

This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.

• Journal of the Korea Society of Computer and Information
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• v.9 no.3
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• pp.135-141
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• 2004

With the diversified and enlarged softwares, the issue of software maintenance became more complex and difficult and consequently, the cost of software maintenance took up the highest portion in the software life cycle. We design Reverse Engineering Tool for software restructuring environment to object-oriented system. We design Rule - Based Reverse - Engineering using Class Information. We allow the maintainer to use interactive query by using Prolog language. We use similarity formula, which is based on relationship between variables and functions, in class extraction and restructuring method in order to extract most appropriate class. The visibility of the extracted class can be identified automatically. Also, we allow the maintainer to use query by using logical language. So We can help the practical maintenance. Therefore, The purpose of this paper is to suggest reverse engineering tool and evaluation reverse engineering tool.

• Journal of Engineering Education Research
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• v.22 no.4
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• pp.71-77
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• 2019

Capstone design is a very important college course that enhances students' creativity and skills. However, in most universities, the operation of capstone design is operated by the experience and intuition of the advisor, and it is somewhat lacking in the generation of useful results such as patent rights and technology start-up from the capstone design result. In this study, we proposed a performance - based capstone design operation model through patent linkage so that the capstone design class can create creative and useful results. The proposed operating model includes support for research on prior art of patent information utilization, patent right of idea, and technology commercialization. The proposed operating model was directly applied to the capstone design class in the university, and it was confirmed that useful results such as expansion of the scope of the research achievement and technology start - up were created compared to the existing operation model.

• International Journal of Control, Automation, and Systems
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• v.5 no.5
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• pp.547-558
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• 2007

This paper proposes a simpler solution to the stabilization problem of a special class of nonlinear underactuated mechanical systems which includes widely studied benchmark systems like Inertia Wheel Pendulum, TORA and Acrobot. Complex internal dynamics and lack of exact feedback linearizibility of these systems makes design of control law a challenging task. Stabilization of these systems has been achieved using Energy Shaping and damping injection and Backstepping technique. Former results in hybrid or switching architectures that make stability analysis complicated whereas use of backstepping some times requires closed form explicit solutions of highly nonlinear equations resulting from partial feedback linearization. It also exhibits the phenomenon of explosions of terms resulting in a highly complicated control law. Exploiting recently introduced Dynamic Surface Control technique and using control Lyapunov function method, a novel nonlinear controller design is presented as a solution to these problems. The stability of the closed loop system is analyzed by exploiting its two-time scale nature and applying concepts from Singular Perturbation Theory. The design procedure is shown to be simpler and more intuitive than existing designs. Design has been applied to important benchmark systems belonging to the class demonstrating controller design simplicity. Advantages over conventional Energy Shaping and Backstepping controllers are analyzed theoretically and performance is verified using numerical simulations.