• Publications of The Korean Astronomical Society
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• v.37 no.1
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• pp.1-11
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• 2022

During the course of analysing both single-dish and very long baseline interferometry (VLBI) data obtained from the Korean VLBI Network (KVN), we found a systematic offset between flux density measurements from different antennas. We were able to attribute a majority of the systematic offsets to changes in the "a priori" antenna gains, which were found to have varied up to 10 percent at 22 GHz and up to 30 percent at 43 GHz. Using historical calibrator observations, we present a revised set of gains that may be applied to KVN data taken from 2015 August to 2019 January. Application of the revised gains to the KVN results in a consistency of correlated flux density measurements between the three baselines of approximately five percent. We found that images from the recalibrated data typically have a 50 percent higher dynamic range, with some cases showing an increase of dynamic range of up to a factor of three.

• Korean Business Review
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• v.17
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• pp.111-136
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• 2004

The aim of this study is to review the improvement method of Korea capital gains tax according to the alienation of the real estate, and to suggest an improvement plan. The study has been carried out by reviewing the related literatures. Capital gains tax could be calculated either using the actual price of sale or the standard prices. Korea capital gains tax has been revised many times since 1975 when it was first enacted. Initially the actual price of sale was the default rule and the standard prices was allowed only exceptionally if the actual price of sale could not be detected. The actual price of sale rather than the standard prices should be used for determining the capital gains tax on the transfer. By doing so, the desired principles of taxation such as "principle of taxation on tax paying ability". In conclusion, the present capital gains tax of Korea should be improved in many aspects in order to promote income redistribution function and efficient allocation of resources.

• Journal of the Korean association of regional geographers
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• v.12 no.5
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• pp.595-613
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• 2006

In the debates of development gains, the general rule is that it results from actions other than those of the landowner, most notably of the public sector as in granting of permissions for the development of specific land uses and densities or through infrastructure investments, or of socio-economic forces due to a general capital accumulation in space. A huge academic literature has investigated the development gains capture that refers to the process by which a portion of or all land value increments attributed to the community effort are recouped by the public sector. Policy instruments for applying development gains capture are based on deepening land value taxation, financing infrastructure, controling land use. But one of the most basic for the efficient policy implementation is the accurate estimation of development gains. This paper estimates the development gains generated by the total 204 building land projects of Korea Land Corporation and Korea National Housing Corporation since 1995.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.698-706
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• 2016

In order to move mobile robots to desired locations in a minimum time, optimal control problems have to be solved; however, their analytic solutions are almost impossible to obtain due to robot nonlinear equations. This paper presents a method to get optimal control gains of mobile robots using genetic algorithms. Since the optimal control gains of mobile robots depend on the initial conditions, the initial condition range is discretized to form some grid points, and genetic algorithms are applied to provide the optimal control gains for the corresponding grid points. The optimal control gains for general initial conditions may be obtained by use of neural networks. So the optimal control gains and the corresponding grid points are used to train neural networks. The trained neural networks can supply pseudo-optimal control gains. Finally simulation studies have been conducted to verify the effectiveness of the method presented in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1811-1817
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• 2014

In this paper, a PID controller with interpolated gains by use of neural networks is proposed for the formation control problem that following robots track a leading robot with constant distances and angles when there are changes in the mass of the following robot. The whole control system is composed of a kinematic controller and a dynamic controller considering the robot dynamics. The dynamic controller is the PID controller with varying gains, and the proper gains are obtained for some representative masses of the follower robot by the genetic algorithm. Neural networks is trained using the genetic algorithm with the gain data obtained in the previous step. The trained neural network determines optimal PID gains for a random mass of following robot. Simulation studies show that for arbitrary masses of the tracking robot, the PID controller with interpolated gains by the trained neural network has better tracking performance than that of the PID controller with fixed gains.

• Journal of Sericultural and Entomological Science
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• v.26 no.2
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• pp.16-25
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• 1984

The sericin fixation of silk fabrics by epoxy resins was studied in the presence of aqueous salt solution in different solvents at the indicated temperature for the desired time. Heavy weight gains were obtained in the reaction with glycerol diglycidyl ether (EX-313) and ethylene glycol diglycidyl ether (EX-810) catalyzed by potassium thiocyanate in such solvents as carbon tetrachloride and p-chloroethylene. The obtained results were summarized as follows; 1) The tested resins were found similar in reaction behavior to silk fabric. The effect of fixation and weight gains was higher in EX-810 than EX-313. 2) The weight gains were increased with reaction time and temperature, and degumming ratio reached a constant value in 90 min at 70$^{\circ}C$. 3) The weight gains and the degumming ratio reached an equilibrium at 3-5% of epoxy concentration. 4) The weight gains were remarkably influenced and increased by the concentration of salt solution. The degumming ratio reached an equilibrium over 0.5N concentration of salt. 5) The weight gains were increased with the dipping time in gently-sloping. The degumming ratio reached an equilibrium over 15 min dipping. 6) The effect of sericin fixation of hydrophobic solvents, such as Carbon Tetrachloride, p-Chloroeth-ylene, Cyclohexane, Xylene and Toluene, was found suitable. 7) The effect of drying temperature was not remarkable on the weight gains and the degumming ratio. 8) There was a slight decrease in the moisture regain of sericin-fixed silk and it may be possible to maintain the moisture regain in the sericin-fixed silk by the epoxy resins. 9) The results on testing physical properties of sericin-fixed silk fabric were as follows; The crease recovery was almost not different from undegummed fabric, but inferior to degummed fabric. The tensile strength was improving in accordance with the effect of sericin fixation, either the elongation did.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.398-403
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• 1993

A rule based fuzzy expert system to self-tune PID controllers is proposed in this paper. The proposed expert system contains two rule bases, where one is responsible for "Long term tuning" and the other for "Incremental tuning". The rule for "Long term tuning" are extracted from the Wills'map and the knowledge about the implicit relations between PID gains and important long term features of the output response such as overshoot, damping and rise time, etc., while 'Incremental tuning" rules are obtained from the relations between PID gains and short term features, error and change in error. In the PID control environment, the proposed expert system operates in two phases sequentially. In the first phase, the long term tuning is performed until long term features meet their desired values approximately. Then the incremental tuning tarts with PID gains provided by the long term tuning procedure. It is noticeable that the final PID gains obtained in the incremental tuning phase are only the temporal ones. Simulation results show that the proposed rule base for "Long term tuning" provides superior control performance to that of Litt and that further improvement of control performance is obtained by the "Incremental tuning'.ance is obtained by the "Incremental tuning'.ing'.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.55-65
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• 2020

The objective of this study is to investigate how investors in the Stock Exchange of Thailand practically trade in response to a magnitude of profits and losses, given a discussion of the widely well-known behavioral explanation, so called as the disposition effect. We provide empirical evidence of an existence of the V-shaped disposition effect, which has been recently found in several advanced equity markets. By adopting the methodology suggested by An's (2016) and Fama and Macbeth (1973), we document that stock return patterns in relation to aggregate unrealized gains and losses of investors are consistent with the V-shaped selling schedule, given an increase in unrealized gains and losses over the period of January 1996 to December 2015. The effect of unrealized gains is stronger than that of unrealized losses and this asymmetry underlies the existence of the V-shaped disposition effect in the Thai equity market. Interestingly, the effect of the V-shaped selling schedule is strongest over the short-term holding time horizon. Last but not the least, stocks for which investors have large unrealized gains and losses outperform in the following month and the long-short trading strategy, based on this premise, generates the average 1.7% monthly (equivalent to 20.0% per year) abnormal return.

• Archives of Plastic Surgery
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• v.46 no.6
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• pp.525-534
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• 2019

Background In microtia patients with bilateral hearing impairment, hearing improvement is crucial for language development and performance. External auditory canal reconstruction (EACR) has been performed to improve hearing, but often results in complications. We performed transcutaneous bone conduction implant (TBCI) surgery in these patients. This study aimed to evaluate the safety and efficacy of TBCI surgery. Methods A retrospective review was performed of five patients who underwent auricular reconstruction and TBCI surgery and 12 patients who underwent EACR between March 2007 and August 2018. Hearing improvement was measured based on the air-bone gap values using pure-tone audiometry over a 6-week postoperative period. We reviewed other studies on hearing improvement using EACR and compared the findings with our results. The surgical techniques for TBCI were reviewed through case analyses. Results Postoperative hearing outcomes showed a significant improvement, with a mean gain of 34.1 dB in the TBCI cohort and 14.1 dB in the EACR cohort. Both gains were statistically significant; however, the TBCI cohort showed much larger gains. Only three of the 12 patients who underwent EACR achieved hearing gains of more than 20 dB, which is consistent with previous studies. All patients who underwent TBCI surgery demonstrated hearing gains of more than 20 dB and experienced no device-related complications. Conclusions TBCI is a safe and effective method of promoting hearing gains in microtia patients with bilateral hearing impairment. TBCI surgery provided better hearing outcomes than EACR and could be performed along with various auricular reconstruction techniques using virgin mastoid skin.

• KDI Journal of Economic Policy
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• v.14 no.3
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• pp.49-72
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• 1992

This paper examines the increasingly popular belief that higher holding tax will be the ultimate solution for Korea's land problems which include excessive concentration of ownership, high and rapidly increasing land prices, and rampant speculation. In principle, land holding tax can supplement capital gains tax in recapturing capital gains from land or suppress returns from land investment returns in line with other forms of asset. This paper shows, however, that the tax burden must be drastically increased for the tax to achieve such goals, and the resistance from tax payers is sure to be intense. As long as the price expectation remains high, as in Korea where land prices have increased 19% annually during the past 18 years, even such increase in the tax may have little impact on landlords' behaviors, the price trend, or the ownership structure. More effective solutions for Korea's land problems are relaxing land use regulations to encourage the supply for urban land and improving the performance of capital gains tax to recapture windfall gains from land. This paper also notes that the so-called "lock-in effect" of the capital gains tax seems to be exaggerated. Land holding tax should be viewed as a revenue raiser for local governments rather than an anti-speculative policy tool. Abandoning unattainable policy goals and adhering to the general principles of taxation, will make land holding tax much simpler, and will better function as a local revenue source.