• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.149-156
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• 2000

Time delay observer (TDO), thanks to the time delay control (TDC) concept, requires little knowledge of a plant model, and hence is easy to design, robust to parameter variation and computationally efficient, yet can reconstruct states rather reliable for nonlinear plant. In this paper, we propose an improved version of TDO that solves two problems inherent in TDO as follows: TDO displays large reconstruction errors due to low-frequency uncertainty and has some restrictions on selecting its gains. By introducing a low pass filter and a state associated with it, we obtain an enhanced time delay observer (ETDO). This observer turns out to have smaller reconstruction errors than those of TDO and not to have any restriction on selecting its gains, thereby solving the problems. Through performance comparison by transfer function and simulation, we validate the analysis results of two observers (TDO and ETDO) and evaluate the performances. Finally, through experiments on BLDC motor system, the analysis results are clearly conformed.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2102-2107
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• 2005

In this paper, a real-time optimization method for nonlinear dynamical systems is proposed. The proposed method is based on the algorithms of numerical solutions for optimal control problems. We deal with a real-time collision-free motion control of a nonholonomic mobile robot, which has input restrictions of actuators. The effectiveness of the algorithmic method is demonstrated through numerical and experimental results. The mobile robot which we have developed is able to avoid moving obstacles skillfully. Therefore the proposed controller works well in real time.

• Journal of the Korea Society of Computer and Information
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• v.21 no.4
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• pp.1-8
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• 2016

In small embedded systems including IoT devices, memory size is very small and it is important to reduce memory amount for execution of application programs. For multi-threaded applications, stack may consume a large amount of memory because each thread has its own stack of sufficiently large size for worst case. This paper presents an implementation of single stack multi-threading, called SSThread (Single Stack Thread), by sharing a stack for all threads to reduce stack memory size. By using SSThread, multi-threaded applications can be programmed based on normal C language environment and there is no requirement of transporting multi-threading operating systems. It consists of several library functions and various C macro definitions. Even though some functional restrictions in comparison to operating systems supporting complete multi-thread functionalities, it is very useful for small embedded systems with tiny memory size and it is simple to setup programming environment for multi-thread applications.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.5
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• pp.277-284
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• 2012

To meet the usage of discrete wavelet transform (DWT) on potable devices, this paper implements 2-level DWT using a reference many-core processor architecture and determine the optimal many-core processor. To explore the optimal many-core processor, we evaluate the impacts of a data-per-processing element ratio that is defined as the amount of data mapped directly to each processing element (PE) on system performance, energy efficiency, and area efficiency, respectively. This paper utilized five PE configurations (PEs=16, 64, 256, 1,024, and 4,096) that were implemented in 130nm CMOS technology with a 720MHz clock frequency. Experimental results indicated that maximum energy and area efficiencies were achieved at PEs=1,024. However, the system area must be limited 140mm2 and the power should not exceed 3 watts in order to implement 2-level DWT on portable devices. When we consider these restrictions, the most reasonable energy and area efficiencies were achieved at PEs=256.

• Journal of Welding and Joining
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• v.8 no.2
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• pp.53-57
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• 1990

Analytic solutions of heat conduction during welding which were first found by Resenthal have some restrictions. One of these is that models to which analytic solutions can be applied must have simple geometric shape, and another is that quasi-stationary state must be created. On the other hand, computational methods developed recently with the aid of the computer can overcome these shortcomings, but the methods raise problems from economic point of view when they are applied to 3 dimensional problems. Taking account of these problems, a new method combinig the analytic method with the computational one is proposed. This method can be ued in weldments with complicated geometric shape in non-stationary state, but with the aid of the analytic method can reduce the computing time.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.11-19
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• 2000

It has been reported that few manufacturers of cement mortar for precast products use chemical and mineral admixture due to the absense of restrictions related to the application of admixture and the poor manufacturing facilities. Therefore, this paper is intended to contribute to the improvement of quality by investigating the properties of cement mortar for precast products using fly ash, blast furnace slag and AE water reducing agent. According to the test results. it was found that the cement mortar products using fly ash and AE water-reducing agent had better qualities than those of ordinary portland cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.81-83
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• 2011

A modular house is a house that is assembled on-site from modularized units. As such units are manufactured in a factory, the construction period is reduced, resources are recycled, and quality is improved. However, the construction technique applied to conventional modular houses has not overcome certain structural restrictions, as it is currently used to build houses less than 4 stories in height, which means that it lacks economic feasibility. For this reason, this research aims to develop a scenario of a construction method for Korean modular housing that can be applied to urban-type housing higher than 12 stories. This research is expected to provide fundamental data necessary for the future development of a construction method for Korean modular housing.

• KIEAE Journal
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• v.5 no.2
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• pp.27-34
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• 2005

The purpose of this study were to examine actual conditions of apartment residents living with their companion animals and to identify their residential stress and needs of planning elements under those conditions. Questionnaire survey was adopted in this study, and 100 cases were used for data analysis. The subjects for this study were limited to the residents breeding pets in their apartments. The results of this study are as follows: Most of the residents share their living spaces with pets together like their family without spatial restrictions. They indicated problems related to breeding pets in their residence such as walking the dog, cleaning home, leaving pets alone, noise and unpleasant smell. However, they didn't seem to be stressed a lot for their living environments. In terms of residential planning elements, floor plans for effective natural ventilation, balcony with sufficient sunlight, sound proof system, easy-maintenance interior material, unlash area, rubbish bin, mechanical ventilation and central vacuum system and safe electric outlet were highly indicated.

• Journal of Korean Association for Spatial Structures
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• v.15 no.3
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• pp.61-68
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• 2015

A study on BRP(Building Rapid Printing) technology is in an initial stage although general 3d printers are being developed in a great speed and with fruitful outputs. Even some laboratories in advanced countries have difficulties in their research due to many technological restrictions and have not produced a practical output yet. This paper proposed distinct directions in which the research of this aera should be developed and this manifested four areas - printing speed, reinforcing tech, material tech and nozzle tech and those areas were proposed with concrete development alternatives and objects.

• International Commerce and Information Review
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• v.11 no.1
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• pp.379-403
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• 2009

The Purpose of this study is to research the problems of trade restriction for an environment protection. Environmental regulation relate to trade are Convention on International Trade in Endangered Species of Wild Fauna & Flora, Montreal Protocol on Substances that Deplete the Ozone Layer, Kyoto Protocol to the UN Framework Convention on Climate Change, Basel Convention on the Control of Transboundary Movements of Hazardous Wastes & Their Disposal, Cartagena Protocol on Biosafty and WTO Agreement. Regulatory action for environmental protection has economics instrument, command & control, liablity, damage compensation, voluntary agreement. In the case of our country, impact of regulatory action for environmental protection is low. Because is recognized position of developing country yet. For in the balance rules of trade and enviroment, First must satisfy WTO's basic principles and principle of quantitative restrictions prohibition, Second, operation of protection action must reasonable and objective standards Third, must satisfy GATT article 20 (b) clause and (g) protestation each essential factor To grow for environment advanced country, we should do i) using of FTA ii) international cooperation strengthening for developing country position iii) construction of environment information network