• Journal of the Ergonomics Society of Korea
• /
• v.20 no.2
• /
• pp.99-111
• /
• 2001

Human factors is a key issue in the maritime industry including ship design and navigation safety. Human factors for ship design is to optimize safety and convenience of crews and passengers. And human factors for navigation safety is to minimize marine accident occurrence by human and organizational error. There are several technical requirements to incorporate human factors and marine system Risk analysis. human behaviour analysis and human M&S(modeling and simulation) are examples of technical requirements. This paper provides the key issues and technologies of human factors for ship design and navigation safety.

• Journal of Communications and Networks
• /
• v.8 no.4
• /
• pp.391-400
• /
• 2006

With the on-going wireless access technologies, the Internet has become accessible anytime anywhere. In wireless networks, link errors significantly degrade the performance of the transmission control protocol (TCP). To cope with this issue, this paper improves the recently-proposed terrestrial REFWA (T-REFWA) scheme by adding a new error recovery mechanism to its original design. In the T-REFWA scheme, senders are acknowledged with appropriate sending rates at which an efficient and fair utilization of network resources can be achieved. As the feedback values are computed independently of link errors, senders can keep transmitting data at high rates even in case of link error occurrences. Using this feature, the proposed error recovery mechanism can achieve high throughput in environments with high bit error rates. The throughput is further improved by disabling the exponential back-off algorithm of TCP so that long idle times are avoided in case of link errors. We show through simulations that the proposed method improves TCP performance in high bit error rates. Compared with several TCP variants, the proposed error recovery scheme exhibits higher link utilization and guarantees system fairness for different bit error rates.

• Journal of KIBIM
• /
• v.6 no.2
• /
• pp.47-57
• /
• 2016

Recently, the introduction and spread of BIM technology has been actively promoted at the domestic level and abroad. However, the BIM adoption and diffusion rate in the whole construction industry has been slower than expected, this is because they applied to construction projects in a way that does not meet the basic objective of BIM adoption. The objective of this paper is to derive a BIM adoption strategy that can provide benefits and efficiency from the design phase, by analyzing issues related to design errors identified in two real world projects based on the 2D to BIM conversion process. Types of issues, type distribution, and degree of BIM contribution to find issues were analyzed in a quantitative way, and then a BIM adoption strategy was derived. As a result, this paper identified that there obviously exists a limit in the 2D to BIM conversion process by repeating the problems that occur in the traditional 2D design process. Therefore, the authors of this paper insist that the design firms should adopt BIM-based design processes, fully, to get financial benefits as well as to improve the design quality.

• Journal of Power Electronics
• /
• v.15 no.2
• /
• pp.378-388
• /
• 2015

This paper proposes a pulse width modulation (PWM)-based sliding mode controller (SMC) for a full-bridge DC-DC converter that can eliminate static output voltage error. Hysteretic SMC in DC-DC converter does not have a fixed switching frequency, and applying hysteretic SMC to full-bridge converters is difficult. Fixed-frequency SMC, which is also called PWM-based SMC, based on equivalent control overcomes these shortcomings. However, the controller order reduction in equivalent control in PWM-based SMC causes static output voltage error. To resolve this issue, an integral item is added to the PWM-based SMC. Sliding mode coefficients are designed by applying a standard second-order system to the sliding mode surface. The effect of adding an integral item on the controller is analyzed, and an integral coefficient design method is proposed. Experiment results on a three-level full-bridge DC-DC converter verify the control scheme and design method proposed in this paper.

• Korean Journal of Computational Design and Engineering
• /
• v.11 no.1
• /
• pp.1-10
• /
• 2006

This paper addresses B-spline curve approximation of a set of ordered points to a specified toterance. The important issue in this problem is to reduce the number of control points while keeping the desired accuracy in the resulting B-spline curve. In this paper we propose a new method for error-bounded B-spline curve approximation based on adaptive selection of dominant points. The method first selects from the given points initial dominant points that govern the overall shape of the point set. It then computes a knot vector using the dominant points and performs B-spline curve fitting to all the given points. If the fitted B-spline curve cannot approximate the points within the tolerance, the method selects more points as dominant points and repeats the curve fitting process. The knots are determined in each step by averaging the parameters of the dominant points. The resulting curve is a piecewise B-spline curve of order (degree+1) p with $C^{(p-2)}$ continuity at each knot. The shape index of a point set is introduced to facilitate the dominant point selection during the iterative curve fitting process. Compared with previous methods for error-bounded B-spline curve approximation, the proposed method requires much less control points to approximate the given point set with the desired shape fidelity. Some experimental results demonstrate its usefulness and quality.

• Journal of Korea Multimedia Society
• /
• v.14 no.2
• /
• pp.194-200
• /
• 2011

Recently, RFID(Radio Frequency IDentification) market spread in industry region is entering a phase of stagnation due to cost issue. RFID tag inlay cost has become relatively more expensive due to the recent decrease in chip price. Therefore, a simple and rapid design technique for RFID tag has yet to be implemented to achieve low cost. This paper presents a design technique considering chip impedance for antenna design for improved accuracy and computation time. As a result, it is confirmed that analysis error for resonance ranges within 20MHz and readable range error falls within 1.5m.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.4
• /
• pp.70-75
• /
• 2011

Nowadays, modern gearboxes are characterized by high torque load demands, low running noise and compact design. Also durability of gearbox is specially a major issue for the industry. For the gearbox which used in wind turbine, gear transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. In this paper, tooth modification for the high speed stage is used to compensate for the deformation of the teeth due to load and to ensure a proper meshing to achieve an optimized tooth contact pattern. The gearbox is firstly modeled in Romax software, and then the various combination analysis of the tooth modification is presented by using Windows LDP software, and the prediction of transmission error under the loaded torque for the helical gear pair is investigated, the transmission error, contact stress, root stress and load distribution are also calculated and compared before and after tooth modification under one torque condition. The simulation result shows that the transmission error and stress under the loads can be minimized by the appropriate tooth modification.

• Laser Solutions
• /
• v.17 no.1
• /
• pp.17-21
• /
• 2014

Head up display is in increasing demand for advanced devices in the modern luxury vehicles. It helps drivers focus on driving environment on the road. While HUD technology with LED has advanced, the brightness in daylight can be still an issue to be resolved. Laser light source is a possible solution to overcome the brightness problem and optimal optics design is required for the best performance. Sample design of optics is proposed and detail procedure of lens design evaluation is presented in this paper. The results were characterized by using a ray tracing method and qualitative analysis for spot and DEE is also presented. The overall error or image distortion remained in the target range of $25{\mu}m$ and the simulated image demonstrated possible use in the automotive applications.

• Journal of Drive and Control
• /
• v.12 no.2
• /
• pp.14-20
• /
• 2015

This paper focuses on the issue of force synchronizing control for the injection servomechanism of injection molding machines. Prior to the controller design, a virtual design model was developed for the injection mechanism with an AC servomotor-ball screw. A synchronizing controller is designed and combined with the PID control to accommodate the mismatches between the real plant and the linear model plant used. Due to the plant uncertainty, the stiffness and the damping of the mechanism were considered. From the tracking control simulations based on the virtual design model, it is shown that a significant reduction in force synchronizing error is achieved through the use of a proposed control scheme.

• Journal of Drive and Control
• /
• v.11 no.2
• /
• pp.9-15
• /
• 2014

This paper deals with the issue of force synchronizing control for the clamping servomechanism of injection molding machines. Prior to the controller design, a virtual design model has been developed for the clamping mechanism with hydraulic systems. Then, a synchronizing controller is designed and combined with an adaptive feedforward control in order to accommodate the mismatches between the real plant and the linear model plant used. As a disturbance, the leakage due to the ring gap with relative motion in the cylinder has been introduced. From the robust force tracking simulations, it is shown that a significant reduction in the force synchronizing error is achieved through the use of a proposed control scheme.