• Interaction and multiscale mechanics
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• v.5 no.3
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• pp.229-265
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• 2012

Hygroexpansion of wood is a known and undesired characteristic in civil engineering. When wood is exposed to changing environmental humidity, it adsorbs or desorbs moisture and warps. The resulting distortions or - at restrained conditions - cracks are a major concern in timber engineering. We herein present a multiscale model for prediction of the macroscopic hygroexpansion behavior of individual pieces of softwood from their microstructure, demonstrated for spruce. By applying poromicromechanics, we establish a link between the swelling pressure, driving the hygroexpansion of wood at the nanoscale, and the resulting macroscopic dimensional changes. The model comprises six homogenization steps, which are performed by means of continuum micromechanics, the unit cell method and laminate theory, all formulated in a poromechanical framework. Model predictions for elastic properties of wood as functions of the moisture content closely approach corresponding experimental data. As for the hygroexpansion behavior, the swelling pressure has to be back-calculated from macroscopic hygroexpansion data. The good reproduction of the anisotropy of wood hygroexpansion, based on only a single scalar calibration parameter, underlines the suitability of the model. The multiscale model constitutes a valuable tool for studying the effect of microstructural features on the macroscopic behavior and for assessing the hygroexpansion behavior at smaller length scales, which are inaccessible to experiments. The model predictions deliver input parameters for the analysis of timber at the structural scale, therewith enabling to optimize the use of timber and to prevent moisture-induced damage or failure.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.66-70
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• 1998

Several liquid crystalline monomers were synthesized and characterized to utilize as new matrix materials of liquid crystal/polymer composite films for display application. Liquid crystalline compounds which have azo group as center link, cyano group at one of the terminal position in common and bromoalkyl(azo(n)), azidoalkyl(AZI(n)), aminoalkyl(ALC(n)) as the terminal group were synthesized and identified respectively by FT-lR, $^1H-NMR$ spectrometer and elemental analysis. All these compounds exhibited nematic liquid crystalline region in the certain temperature range as determined by DSC and polarized optical microscope. These liquid crystalline compounds also showed a typical even-odd effect in both $T_{KN}$ and $T_{NI}$ due to conformational change as the length of terminal alkyl chain, $-(CH_2)n-$. was varied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.8
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• pp.1250-1258
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• 1997

This paper reports on the development of a new foot for a quadrupedal jointed-leg type walking robot. The foot has 2 toes, one at the front and the other at the rear side, for stable landing on uneven ground by point contact. The toes can move up and down independantly, guided by double-wishbone shaped parallel links which enable the lower leg to rotate with respect to a remote center on the ground surface. The motion of each toe is damped by a hydropneumatic shock absorber integrated in the foot in order to absorb the dynamic landing shock. Furthermore, the new foot can reduce the maximum hip joint drive torque by shortening the moment arm length between the hip joint and the landing force vector on the ground. Intensive experiments were carried out in this study by using a one-leg walking model to investigate the soft landing performance of the foot which could be hardly offered by conventional robot feet such as a flat plate with a gimbal type ankle joint. And it was confirmed that the hip joint torque of the leg walking on the flat surface could be reduced remarkably by using the new foot.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.67-74
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• 2007

Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.788-797
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• 2003

Class library is one of the most crucial element of Java runtime environment in addition to Java virtual machine. In particular, embedded Java system depends heavily on the class library due to having a low bandwidth communication link and a small amount of memory which are a common restriction of embedded system. It is therefore quite necessary to find the characteristic of the class library for embedded Java system to build an efficient Java runtime environment. In this paper we have analyzed the characteristic of the class library for embedded system. The analysis includes sorts of classes in the library, typical size of the file which contains the class, and the composition of constant pool which is a major part of the file. We also have found typical number of field and method a class contains, the sizes of stack and local variable array each method requires, and the length of bytecode in the method. The result of this study can be used to estimate the startup time for class loading and the size of memory to create an instance of class which are a mandatory information to design an efficient embedded Java virtual machine.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.647-653
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• 2016

Background: Breast cancer is the most common type of cancer affecting Malaysian women. Recent statistics revealed that the cumulative probability of breast cancer and related deaths in Malaysia is higher than in most of the countries of Southeast Asia. Single nucleotide polymorphisms (SNPs) in CYP2E1 (rs6413432 and rs3813867), STK15 (rs2273535 and rs1047972) and XRCC1 (rs1799782 and rs25487) have been associated with breast cancer risk in a meta-analysis but any link in Southeast Asia, including Malaysia, remained to be determined. Hence, we investigated the relationship between these SNPs and breast cancer risk among Malaysian women in the present case-control study. Materials and Methods: Genomic DNA was isolated from peripheral blood of 71 breast cancer patients and 260 healthy controls and subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Results: Our study showed that the c1/c2 genotype or subjects with at least one c2 allele in CYP2E1 rs3813867 SNP had significantly increased almost 1.8-fold higher breast cancer risk in Malaysian women overall. In addition, the variant Phe allele in STK15 rs2273535 SNP appeared to protect against breast cancer in Malaysian Chinese. No significance association was found between XRCC1 SNPs and breast cancer risk in the population. Conclusions: This study provides additional knowledge on CYP2E1, STK15 and XRCC1 SNP impact of risk of breast cancer, particularly in the Malaysian population. From our findings, we also recommend Malaysian women to perform breast cancer screening before 50 years of age.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.98-107
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• 2000

This paper compares the performance of feedback consolidation algorithms with or without a fast overload indication function which has been recently proposed in the ATM Forum for multicast ABR (Available Bit Rate) services in ATM networks. We use the performance criteria such as the ACR (Allowed Cell Rate) of a source, queue length at a switch, link utilization, fairness, and BRM (Backward Resource Management) cell overhead. Simulation results show that performance of the feedback consolidation algorithms with a fast overload indication function can be improved sign.ificantly than that of algorithms without this function in terms of ramp-down delay, particularly in initial start-up period or under a severe overload situation. The fast overload indication function can be combined with any feedback consolidation algorithm, whereas its performance is highly dependent on an underlying basic feedback consolidation algorithm.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.792-802
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• 2009

The objective of this study is to construct the watershed management system with link of the non-point sources model and to estimate delivery ratio duration curves for various pollutants. For the total water pollution load management system, non-point source model should be performed with the study of the characteristic about non-point sources and loadings of non-point source and the allotment of pollutant in each area. In this study, daily flow rates and delivered pollutant loads of Nakdong river basin are simulated with modified TANK model and minimum variance unbiased estimator and SWAT model. Based on the simulation results, flow duration curves, load duration curves, and delivery ratio duration curves have been established. Then GIS analysis is performed to obtain several hydrological geomorphic characteristics such as watershed area, stream length, watershed slope and runoff curve number. As a result, the SWAT simulation results show good agreements in terms of discharge, BOD, TN, TP but for more exact simulation should be kept studying about variables and parameters which are needed for simulation. And as a result of the characteristic discharges, pollutants loading with the runoff and delivery ratios, non-point sources effects were higher than point sources effects in the small-scale test bed of Nakdong river basin.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.137-154
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• 2019

This study analysed the center control emergency vehicle preemption[EVP] test result on the 1.782 km section around Gangbuk Fire Station. The pros and cons between center control and site control EVP was compared through the review of existing research. The test site was selected based on the higher link speed for choosing low congested area and 4 to 6 lane road. EVP operates green extension under the estimated arrival time to each intersection. This study is about EVP system field application and its evaluation by analyzing EVP operation result with the emergency vehicle's trace, GPS data. The impact on the surrounding traffic was analysed in delay from the queue length survey. Analysis showed the decrease in averge travel time 41.81%, but the increase in delay of surrounding traffic slightly. It is expected that EVP can be applied to the expanded area by researching EVP compensation scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1163-1168
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• 1999

This paper proposes a wireless positioning method using the CDMA mobile communicaton network. The proposed method is time-based positioning method that uses mobile-station arrival time of forward link signal from base-stations. In this mehtod there are TDOA and TOA methods that use time-difference-of-arrival and time-of-arrival, respectively. Error characteristics and implementation simplicity of the two methods are compared and analyzed each other. As a results, it showed that TDOA has advantage of less sensitivity to the time error compared to TOA but has disadantage of more sensitivity to the spatial error. Also, from architecture of the CDMA system that is time synchronized to only active base-station it is analyzed that adoption of TDOA method is more advantageous than TOA because time difference of signal arrival from the neighbor base-stations against the active base-station can be measured more easily. Therefore, conclusion is made that TDOA is beat suit to the time-based positioning method for the present CDMA mobile communication networkgorithm performs block-by-block coherent decoding with the aid of pilot symbols. It is shown that the complexity of the algorithm grows linearly as a function of sequence length. The performance of the algorithm is shown to better than that of the conventional pilot symbol aided (PSI) algorithm. Simulation results are presented to assess the performance of the algorithm and the results are compared with that of the conventional PSI alforithm.