• Korean Journal of Construction Engineering and Management
• /
• v.14 no.5
• /
• pp.35-43
• /
• 2013

Nowadays the widely used media in architecture include visualizations, animations and three-dimensional models. 3D digital methods using active CAM(Computer Aided Manufacturing) and CNC(Computerized Numerical Control) imaging have been developed for accurate shape and 3D measurements in freeform buildings. In contrast to a conventional building using auto CAD system and others, the proposed digital optimization method is based on a combination of 3D numerical data and parametric 3D model for design and construction. The objective of this paper is therefore to present digital optimization process for constructability of freeform building. The method can be useful in the effective implementation of an error-proofing process of freeform building during design and construction phase. 3D digital coordinate data can be used effectively to identify correct size of structural and finish members and installation location of each members in construction field. In addition, architects, engineers and contractors can evaluate design, materials, constructability and identify error-proofing opportunities. Other project participants can also include representatives from all levels of management, departments as well as workers and key subcontractors' personnel, if necessary. The 3D digital optimization process is therefore appropriate to serious variations in freeform shape. For future study, the developed digital optimization method is necessary to be carried out to verify the robustness and accuracy for constructability in construction field.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.12
• /
• pp.45-51
• /
• 2010

The main issue in mobile cloud computing is how to support a seamless service to a mobile mode. Mobile IPv6 (MIPv6) is a mobility supporting protocol which is standardized by the Internet Engineering Task Force (IETF). Mobile IPv6 fast handovers (FMIPv6) is the extension of MIPv6 which is proposed to overcome shortcomings of MIPv6. Recently, fast handovers for Mobile IPv6 over IEEE 802.16e which is one of broadband wireless access systems has been proposed by the IETF. It was designed for supporting cross-layer fast handover. In this paper, we propose an enhanced cross-layering mobile IPv6 fast handover over IEEE 802.16e networks. In our scheme, a new access router generates a new address for the mobile node by using a layer 2 trigger. We utilize a layer 2 message which is sent from a new base station to the new access router in order to inform the new access router of information of the mobile node. A previous access router sends a binding update message to the mobile node's home agent when it acquires the new address of the mobile node. We evaluate the performance of the proposed scheme compared with the existing schemes in terms of the signaling cost and the handover latency. From the results, we observe that the proposed scheme can support fast handover effectively over IEEE 802.16e networks than existing schemes.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.10
• /
• pp.36-42
• /
• 2010

FFT(Fast Fourier Transform) processor is one of the key components in the implementation of OFDM systems for many wireless standards such as IEEE 802.22. To improve the performances of FFT processors, various studies have been carried out to reduce the complexities of multipliers, memory interface, control schemes and so on. While the number of FFT stages increases logarithmically $log_2N$) as the FFT point-size (N) increases, the number of required registers (or, memories) increases linearly. In large point-size FFT designs, the registers occupy more than 70% of the chip area. In this paper, to reduce the memory size of IFFT for OFDM transmitters, we propose a new IFFT design method based on a combined mapping of modulated data, pilot and null signals. The proposed method focuses on reducing the sizes of the registers in the first two stages of the IFFT architectures since the first two stages require 75% of the total registers. By simulations of 2048-point IFFT design for cognitive radio systems, it is shown that the proposed IFFT design method achieves more than 38.5% area reduction compared with previous IFFT designs.

• Journal of the Korea Concrete Institute
• /
• v.17 no.6 s.90
• /
• pp.993-1000
• /
• 2005

Various types of FRP materials have been applied for structural strengthening of RC beams in various forms. When CFRP plates are used, a premature failure used to occur before enough strengthening effect appears. This is primarily due to the rip-off of CFRP Plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, its failure mechanism is not definitely clarified yet. Investigations from literatures have shown that the rip-off failure is dependant on the vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to Investigate the rip-off failure load based on the stress states at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. It is believed that the proposed model can be successfully used to provide more information on the rip-off failure mechanisms and its prevention.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.10
• /
• pp.97-107
• /
• 2013

The latest programming paradigm has been mostly geared toward object-oriented programming and visual programming based on the object-oriented programming. However, object-oriented programming has a more difficult and complicated concept compared with that of existing structural programming technique; thus it has been very difficult to educate students in the IT-related department. This study designed and implemented a Java robot training kit in which the Java virtual machine is built so that it may enhance the desire and motivation of students for learning the object-oriented programming using the training kit which is possible to attach various input and output devices and to control a robot. The developed Java robot training kit is able to communicate with a computer through the USB interface, and it also enables learners to manufacture a robot for education and to practice applied programming because there is a general purpose input and output port inside the kit, through which diverse input and output devices, DC motor, and servo motor can be operated. Accordingly, facing the IT fusion era, the wall between the academic circles and the major becomes lower and the need for introducing education about creative engineering object-oriented programming language is emerging. At this point, the Java robot training kit developed in this study is expected to make a great commitment in this regard.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.30 no.3 s.47
• /
• pp.427-438
• /
• 2004

Cosmeceuticals products we not the products simply for moisturizing and protecting skin but the ones for encouraging to make improvements on wrinkles and helping to whiten, tan, and protect skin against ultraviolet light. In a broader sense, they refer to products with aiming to maintain healthy condition of skin such that skin troubles could be improved or aging of skin could be delayed. However, cosmeceuticals should not have any side effects because they are applied to the whole body for a long period of time differing from medical products which are used on specific areas for a short time. The number of such cosmeceuticals has increased from 500 in 2001 to 2300 in 2003. In order to develop and broaden the scope of cosmeceuticals, the concept of cosmetics needs to be changed from caring skin to delaying aging of the skin and reviving cells. For this purpose, high-valued materials should be developed through basic researches related to the biological function of skin, in vivo experiment and reaction of skin in response to various stimuli using biotechnologies and bioengineering methods. At the same time, it should be proceeded to develop new nano materials for overcoming skin barriers and transfer matericals for helping to absorb effective substances and maintaining stability.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.5
• /
• pp.107-116
• /
• 2011

In this paper, a traffic adaptive sleep based medium access control (TAS-MAC) protocol for wireless sensor networks (WSNs) is proposed. The protocol aims for WSNs which consist of clustered sensor nodes and is based on TDMA-like schema. It is a typical schedule based mechanism which is adopted in previous protocols such as LEACH and Bit-Map Assisted MAC. The proposed MAC, however, considers unexpected long silent period in which sensor nodes have no data input and events do not happen in monitoring environment. With the simple traffic measurement, the TAS-MAC eliminates scheduling phases consuming energy in previous centralized approaches. A frame structure of the protocol includes three periods, investigation (I), transmission (T), and sleep-period (S). Through the I-period, TAS-MAC aggregates current traffic information from each end node and dynamically decide the length of sleep period to avoid energy waste in long silent period. In spite of the energy efficiency of this approach, the delay of data might increase. Thus, we propose an advanced version of TAS-MAC as well, each node in cluster sends one or more data packets to cluster head during the T-period of a frame. Through simulation, the performance in terms of energy consumption and transmission delay is evaluated. By comparing to BMA-MAC, the results indicate the proposed protocol is more energy efficient with tolerable expense in latency, especially in variable traffic situation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.7
• /
• pp.715-725
• /
• 2010

Orthgonal Frequency Division Multiplexing(OFDM) system is effective for the high data rate transmission in the frequency selective fading channel. In this paper we propose PAPR(Peak to Average Power Ratio) reduction method of problem in OFDM system used Fuzzy theory that often control machine. This thesis proposes PAPR reducing method of OFDM system using Fuzzy theory. The advantages for using Fuzzy theory to reduce PAPR are that it is easy to manage the data and embody the hardware, and required smaller amount of operation. Firstly, we proposed simple algorithm that is reconstructed at receiver with transmitted overall PAPR which is reduced PAPR of sub-block using Fuzzy. Although there are some drawbacks that the operation of the system is increased comparing conventional OFDM system and it is needed to send the information about Fuzzy indivisually, it is assured that the performance of the system is enhanced for PAPR reducing. To evaluate the perfomance, the proposed search algorithm is compared with the proposed algorithm in terms of the complementary cumulative distribution function(CCDF) of the PAPR and the computational complexity. As a result of using the QPSK and 16QAM modulation, Fuzzy theory method is more an effective method of reducing 2.3 dB and 3.1 dB PAPR than exiting OFDM system when FFT size(N)=512, and oversampling=4 in the base PR of $10^{-5}$.

• Journal of Biomedical Engineering Research
• /
• v.25 no.6
• /
• pp.471-478
• /
• 2004

Electromyogram (EMC) signal generated by voluntary contraction of muscles is often used in a rehabilitation devices such as an upper limb prosthesis because of its distinct output characteristics compared to other bio-signals. This paper proposes an EMG-based human-computer interface (HCI) for the control of the above-elbow prosthesis or the wheelchair. To control such rehabilitation devices, user generates four commands by combining voluntary contraction of two different muscles such as levator scapulae muscles and flexor-extensor carpi ulnaris muscles. The muscle contraction is detected by comparing the mean absolute value of the EMG signal with a preset threshold value. However. since the time difference in muscle firing can occur when the patient tries simultaneous co-contraction of two muscles, it is difficult to determine whether the patient's intention is co-contraction. Hence, the use of the comparison method using a single threshold value is not feasible for recognizing such co-contraction motion. Here, we propose a novel method using double threshold values composed of a primary threshold and an auxiliary threshold. Using the double threshold method, the co-contraction state is easily detected, and diverse interface commands can be used for the EMG-based HCI. The experimental results with real-time EMG processing showed that the double threshold method is feasible for the EMG-based HCI to control the myoelectric prosthetic hand and the powered wheelchair.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.1-8
• /
• 2016

In this study, an WiFi fingerprinting method based on the k-nn algorithm was applied to improve the accuracy of location tracking of a moving train on a platform and evaluate the performance to minimize the estimation error of location tracking. The data related to the position of the moving train are monitored by the control center for trains and used widely for the safety and comfort of passengers. The train location tracking methods based on WiFi installed by telecom companies were evaluated. In this study, a simulator was developed to consider the environments of two cases; in already installed WiFi devices and new installed WiFi devices. The developed simulator can simulate the localized estimation of the position under a variety of conditions, such as the number of WiFi devices, the area of platform and entry velocity of train. To apply location tracking algorithms, a k-nn algorithm and fuzzy k-nn algorithm were applied selectively according to the underlying condition and also four distance measurement algorithms were applied to compare the error of location tracking. In conclusion, the best method to estimate train location tracking is a combination of the k-nn algorithm and Minkoski distance measurement at a 0.5m grid unit and 8 WiFi AP installed.