• Journal of East-Asian Urban History
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• v.3 no.1
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• pp.57-82
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• 2021

This article examines the urban example of Batu Sawar which served as the capital of the Johor kingdom between 1587 and circa 1615. Around the middle of the eighteenth-century European reference works continued to describe Batu Sawar as the capital of Johor, even though the city had long ceased to serve as a trading center, let alone as Johor's capital, and probably no longer existed. Such observations raise the question of urban impermanence-the transience of sizeable settlements with reference to the Malay Archipelago. Two overarching questions form the backbone of the investigation: First, why did Batu Sawar rise as a regional trading center, and second, what are the reasons that contributed to its decline? Batu Sawar's fate was sealed by a combination of factors that included poor defenses, multiple external shocks, destruction by fire, court politics and rivalry between the early colonial powers.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.346-351
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• 1998

In design of a digital current controller for a 3-phase (3 ) voltage-source (VS) PWM converter, its conventional model, i.e., stationary or synchronous reference frame model, is used in obtaining its discretized version. It introduces, however, inherent errors since the following practical problems are not taken into consideration: the characteristics of the space vector-based pulse-width modulation (SVPWM) and the time delays in the process of sampling and computation. In this paper, the new hybrid reference frame model of the 3 VS PWM converter is proposed considering these problems. In addition, the direct digital current controller based on this model is designed without any prediction or extrapolation algorithm to compensate the time delay. So the control algorithm is made very simple. It represents no steady-state error in input current control and has the optimized transient responses. The validity of the proposed algorithm is proved by the computer simulation and experimental results.

• Journal of Ocean Engineering and Technology
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• v.37 no.6
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• pp.256-265
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• 2023

Many numerical methods have been developed since 1961, but unresolved issues remain. This study developed a numerical method to address these issues and determine the coefficients and properties of rotational waves with a shear current in a finite water depth. The number of unknown constants was reduced significantly by introducing a wavelength-independent coordinate system. The reference depth was calculated independently using the shooting method. Therefore, there was no need for partial derivatives with respect to the wavelength and the reference depth, which simplified the numerical formulation. This method had less than half of the unknown constants of the other method because Newton's method only determines the coefficients. The breaking limit was calculated for verification, and the result agreed with the Miche formula. The water particle velocities were calculated, and the results were consistent with the experimental data. Dispersion relations were calculated, and the results are consistent with other numerical findings. The convergence of this method was examined. Although the required series order was reduced significantly, the total error was smaller, with a faster convergence speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.450-456
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• 2016

STDR (sequence time domain reflectometry) to detect a cable fault using a pseudo noise sequence as a reference signal, and time correlation analysis between the reference signal and reflection signal is robust to noisy environments and can detect intermittent faults including open faults and short circuits. On the other hand, if the distance of the fault location is far away or the fault type is a soft fault, attenuation of the reflected signal becomes larger; hence the correlation coefficient in the STDR becomes smaller, which makes fault detection difficult and the measurement error larger. In addition, automation of the fault location by detection of phase and peak value becomes difficult. Therefore, to improve the cable fault detection of a conventional STDR, this paper proposes the algorithm in that the peak value of the correlation coefficient of the reference signal is detected, and a peak value of the correlation coefficient of the reflected signal is then detected after removing the reference signal. The performance of the proposed method was validated experimentally in low-voltage power cables. The performance evaluation showed that the proposed method can identify whether a fault occurred more accurately and can track the fault locations better than conventional STDR despite the signal attenuation. In addition, there was no error of an automatic fault type and its location by the detection of the phase and peak value through the elimination of the reference signal and normalization of the correlation coefficient.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.1
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• pp.29-35
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• 2015

Dissolved nutrients in seawater are recognized as an essential biogeochemical factor for detecting global environmental changes. The importance of nutrient reference material for seawater has been increased greatly for the comparison of nutrient data, measured in different time and space in global ocean by various researchers with different levels in nutrient analysis skill. In this study, we described the homogeneity and stability of nutrient reference material for seawater using natural seawater, collected at a station of Shihwa Lake, at a coastal station near Uljin (surface water), and at a station over the Ulleung Basin (surface water and 1500 m depth water) and sterilized. Based on the homogeneity data, the nutrient reference materials has similar homogeneity compared to other nutrient reference materials. During 3-13 month period, there was no unidirectional trend of increase or decrease in nutrient concentration of newly developed nutrient reference material for seawater. However, a sustained measurement is required to check stability for longer period.

• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.394-404
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• 2021

The objective of this study was to evaluate quality characteristics of low-nitrite emulsified-sausages (ESs, < 75 ppm) containing paprika oleoresin solution (POS) for replacing sodium nitrite (NaNO2). Pork ESs were prepared with four treatments (reference (REF), 150 ppm NaNO2; TRT1, 0 ppm NaNO2 + 0.1% POS; TRT2, 37.5 ppm NaNO2 + 0.1% POS; and TRT3, 75 ppm NaNO2 + 0.1% POS). The physicochemical and texture properties, microbial counts, residual nitrite and thiobarbituric acid reactant substances (TBARS) were measured during refrigerated storage of 35 days. Although TRT2 and TRT3 had lower levels of NaNO2, they had higher redness and yellowness than REF (p < 0.05). Microbial counts of total bacterial counts and Enterobacteriaceae of TRT2 and TRT3 were similar to those of REF (p > 0.05). Expressible moisture percentages (EM, %) of TRT2 and TRT3 were lower than those of REF (p < 0.05). TBARS values of TRT2 and TRT3 were not different from those of REF (p > 0.05). Among treatments, TRT1 had the highest TBARS values (p < 0.05). In conclusion, 0.1% POS in combination with 37.5 ppm NaNO2 would have quality characteristics similar to those of REF. Therefore, approximately 3/4 of the initial nitrite level could be replaced with 0.1% POS, and eventually developed healthier pork products.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.2
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• pp.88-95
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• 1996

It is inevitable for local systems to have deviations which represent interactions and modeling errors originated from the decomposition process of a large scale system. This paper presents a decentralized control scheme for interconnected systems using local linear models and a neuro-coordinator. In the proposed method, the local system is composed of a linear model and unknown deviations caused by linearizing the subsystems around operating points or by estimating parameters of the subsystems. Because the local system has unmeasurable deviations we define a local reference model which consists of a local linear model and a neural network to estimate the deviations indirectly. The reference model is reformed into a linear model which has no deviations through a transformation of input variables and we obtain an optimum feedback control law which minimizes a local performance index. Finally, we derive a decentralized feedback control law which consists of local linear states and neural network outputs. In the decentralized control, the neuro-coordinator generates a corrective control signal to cancel the effect of deviations through backpropagation learning with the errors obtained from the differences of the local system outputs and reference model outputs. Also, the stability of local system is proved by the degree of learning of the neural network under an assumption on a neural network learning index. It is shown by computer simulations that the proposed control scheme can be applied successfully to the control of a biased two-link planar robot manipulator.

• Journal of Korean Library and Information Science Society
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• v.12
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• pp.35-59
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• 1985

User fees have been employed by libraries as far back as the mid-1800s in both United States and England. By the late 1800s and early : 1900s, the charging of user fees for some library products and services had become a reality in many public and academic libraries. Yet the practice has created controversy when computer-aided reference service began to charge especially in the publicly funded libraries. There are two extream arguments on library reference service fees : one is for and the other is against. most fee o n.0, pponents base their stand on morality. They argue that charging fees for any service is wrong because it violates the user's right of access to information and regard it as an act of decrease human life chances as well as an act of censor. But those who favour fees argue that it is necessary to separate the rhetoric from the reality and to distinguish what libraries are from what they do. The study revealed that library has two options. One is strict free of charge and the other is charging for selected library services. Whatever options the library may take, library had to decide an overall reference service policy. The level and scope of service, audience, necessary fund (who and how) and many other physical and metaphysical things must be considered. However, the first option will necessary be to limit services while there is no loss of traditional philosophical service element. Yet, if to provide a wide range of choices and to create conditions more hospitable to competition from the private information sector and for better evolutional selection, the second option(fee-based service) gives more benefit to the users while there is a loss of fundamental service philosophy.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.82-91
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• 1997

In this paper, a design method of the boiler-turbine control system in the coal fired power plant is proposed. We need to control electric output and drum pressure and water level in drum to guarantee stable operation and save energy for generating electricity and decrease air pollution in the boiler-turbine system. This boiler-turbine control system is composed of reference model part and model following part. The multivariable boiler-turbine system is separated into 3 SISO(Single Input Single Output) systems applying the concept of relative gain matrix. Each 3 reference models for separated boiler-turbine system are composed of 1st order nominal plant and hysteresis integral control system and they make good dy¬namic response with no overshoot and fast rising time. Each fuzzy controller to follow as close as possible to the response of each reference model is designed. The robustness and the good tracking property can be achieved using 5150 fuzzy controllers when there are modeling errors, disturbances and parameter pertur¬bations. The effectiveness of the proposed design method is verified through simulations.

• Journal of Environmental Impact Assessment
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• v.21 no.5
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• pp.631-648
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• 2012

The integrative ecological approaches of chemical assessments, physical habitat modelling, and multi-metric biological health modelling were applied to Gwanpyeong Stream within Gap-Stream watersheds to evaluate environmental impacts on the constructions of residential and commercial complex. For the analysis, the surveys conducted from 45 sites of reference streams within the Gap-Stream watershed and 3 regular sites during 2009 - 2010. Physical habitat health, based on the habitat model of Qualitative Habitat Evaluation Index(QHEI) declined from the headwaters(good - fair condition) to the downstream(poor condition). Chemical water quality, based turbidity and electric conductivity(EC), was degraded toward to the downstream, and especially showed abrupt increases, compared to the values of control streams(CS). Also, concentrations of chlorophyll-a in the downstreams were greater compared to the control stream(CS), indicating an eutrophication. Biological health conditions, based on the Index of Biological Integrity(IBI) using fish assemblages, averaged 19.3 which is judged as a fair condition by the biological criteria of the Ministry of Environment, Korea. The comparisons of model metric values in sensitive species and riffle-benthic species on the Maximum Species Richness Line(MSRL) of 45 reference streams indicated a massive disturbances in all sampling locations. Also, tolerance guild and trophic guild analyses suggest that dominances of tolerant species and omnivores were evident, indicating a biological degradation by habitat disturbances and organic matter pollutions. There was no distinct longitudinal variations of IBI model values from the headwater to the downstream in spite of slight chemical and habitat health gradients among the sampling sites. Overall, integrative ecological health(IEH) scores, based on the chemical, physical, and biological parameters, were low compared to the 45 reference streams due to physical and chemical disturbances of massive constructions of the residential and commercial complex. This stream, thus showed a tendency of typical urban streams which are disturbed in the chemical water quality, habitat structures, and biological integrity. Effective stream management plans and restoration strategies are required in this urban stream for improving integrative stream health.