• Journal of Ecology and Environment
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• v.48 no.2
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• pp.137-143
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• 2024

Background: The study was carried out to analyze the temporal changes of trade-offs (TOs) between two ecosystem services (ESs) before and after thinning in a Pinus koraiensis plantation on Mt. Gari from 2006 to 2021. As target variables, aboveground carbon (AGC) storage and species richness (SR) were chosen for regulating and supporting services. Thinning was applied from 2007 through 2008 with three treatments: 1) light thinning (LT), 2) heavy thinning (HT), and 3) control (Con). Results: Thinning influenced both AGC and SR. In 2021, AGC in the Con (111.1 t C ha^-1) was significantly higher compared to the LT (82.0 t C ha^-1) and HT (60.4 t C ha^-1) after thinning from 2007 to 2008. Also, SR was marginally higher in the LT (94 species) than in the Con (55 species) and HT (87 species) in 2011. Relative benefits of AGC and SR showed similar trends with the obtained values. In addition, the effects of thinning on TO varied among treatments and over time, demonstrating different degrees of TO between the two ESs. In the LT, TO was 0.13 in 2006 and slightly increased to 0.2 by 2021. TO in the HT exhibited a relatively rapid increase from 0.22 in 2006 to 0.58 by 2021, while To in the Con fluctuated, rising to 0.36 in 2011 from 0.1 in 2006 and decreasing to 0.25 by 2021. Among the three treatments, the degree of TOs between the two ESs was the lowest in the LT. Conclusions: Depending on thinning intensities, the responses of ESs and the degree of TOs vary. Regarding the balance between enhancements and TOs in ESs among treatments, the LT treatment showing intermediate carbon storage, higher SR, and lower TOs will be a proper silvicultural application.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.678-684
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• 2018

In order to broaden the indication of middle ear implant, research has been actively conducted on the reverse output method that stimulates the round window. However, it is very difficult to transmit the vibration output effectively because the indivisual anatomical difference of the round window niche is very large and also the visual field is not secured even by a skilled otolaryngologic surgeon. In this paper, we propose a new reverse stimulation method of middle ear implants that transmits energy to the inner ear by using air as a medium. This can compensate for the disadvantages of the conventional method of transmitting vibration energy and minimizes the energy transfer efficiency interference due to the combination of the excitation point and the output device. It was shown that forward and backward transfer characteristics were obtained by cadaveric experiments, and it was shown that it can overcome the acoustical impedance of high round window and transmit energy to inner ear. The receiver, which is the output device of the conventional hearing aids, can generate a constant volume velocity, so it can have a high output at a limited volume, such as a round window niche. So, suggested method can overcome the high acoustical impedance of the round window and deliver acoustic energy to the inner ear.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.165-165
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• 2014

In this study, we demonstrated that the soft lithographic patterning processing of chemical vapor deposition (CVD) graphene and rGO sheets as large scale, low cost, high quality and simplicity for future industrial applications. Recently, a previous study has reported that single layer graphene grown via CVD was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp [1]. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide (DMSO) molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface [2]. Further, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or simple and efficient chemical sensor consisting of reduced graphene oxide (rGO) and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.44-48
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• 2014

A liquid nitrogen-cooled prepolarization ($B_p$) coil made for ultra-low field nuclear magnetic resonance and magnetic resonance imaging (ULF-MR) designed to generate 7 mT/A was fabricated. However, with suspected internal insulation failure, the coil was investigated in order to find out the source of the failure. This paper reports detailed build of the failed $B_p$ coil and a number of analysis methods utilized to figure out the source and the mode of failure. The analysis revealed that pyrolytic graphite sheet linings put on either sides of the coil for better thermal conduction acted as an electrical bridge between inner and outer layers of the coil to short out the coil whenever a moderately high voltage was applied across the coil. A simple model circuit simulation corroborated the analysis and further revealed that the failed insulation acted effectively as a damping resistor of $R_{d,eff}=6{\Omega}$ across the coil. This damping resistance produced a 50 ms-long voltage tail after the coil current was ramped down, making the coil not suitable for use in ULF-MR, which requires complete removal of magnetic field from $B_p$ coil within milliseconds.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.419-425
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• 2015

When a train is delayed because of a disturbance, the time interval between successive trains increases and high-frequency metro lines can become unstable. Time interval control is therefore necessary in preventing such instabilities. In this paper, we propose an optimal interval control algorithm that is easy-to-implement and that guarantees system stability. In the proposed method, the controlled trains are determined from the time interval deviations between successive trains; the control algorithm for staying time is designed by use of a discrete traffic model to ensure an optimal time interval between successive trains. The results of a computer simulation are also given to demonstrate the validity of the proposed algorithm.

• International Area Studies Review
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• v.16 no.3
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• pp.239-266
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• 2012

The purpose of this paper is to suggest desirable improvement for KRX derivatives market plagued with many problems in spite of its world level of quantitative growth. In order to try to find desirable improvement for KRX derivatives market which has many problems like that, I suggest various ways of improvement for regulatory system in the future in terms of behavioral regulation for investor protection. First of all, in order to relieve speculative tendency of trading, KOSPI200 option market with ATM-oriented option trading needs to be induced from the market in which OTM-oriented option is now trading. So discount or exemption of brokerage fee for ATM trading and the introduction of market-maker for ATM type can be considered. For the protection of individual investors, we suggest feasible plans such as differential regulation between professional and individual investors, consolidation of basic deposit management, and enlargement of opportunities for risk management education & simulation trading.

• International Area Studies Review
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• v.13 no.3
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• pp.145-161
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• 2009

Applying the shift-share analysis, this paper decomposes FDI inflow into Korea for the period of 2003-2006. The paper finds that Korea has been lagging behind the world average in absorbing inward FDI, thereby recording negative aggregate industry-mix effects and negative aggregate competitive effects as well. However, the following industries have recorded positive competitive effect: electrical and electronic equipment, motor vehicles and other transport equipment, hotels and restaurants, transport, storage and communications, finance, and business services. In a nutshell, Korea is revealed to have competitive advantage in absorbing inward FDI in a few manufacturing industries and most of service industries. Government policies should accordingly be focused on these industries to encourage more inward FDIs.

• Progress in Superconductivity
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• v.7 no.1
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• pp.28-35
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• 2005

We propose a method to measure atrial arrhythmias (AA) such as atrial fibrillation (Afb) and atrial flutter (Afl) with a SQUID magnetocardiograph (MCG) system. To detect AA is one of challenging topics in MCG. As the AA generally have irregular rhythm and atrio-ventricular conduction, the MCG signal cannot be improved by QRS averaging; therefore a SQUID MCG system having a high SNR is required to measure informative atrial excitation with a single scan. In the case of Afb, diminished f waves are much smaller than normal P waves because the sources are usually located on the posterior wall of the heart. In this study, we utilize an MCG system measuring tangential field components, which is known to be more sensitive to a deeper current source. The average noise spectral density of the whole system in a magnetic shielded room was $10\;fT/{\surd}Hz(a)\;1\;Hz\;and\;5\;fT/{\surd}Hz\;(a)\;100\;Hz$. We measured the MCG signals of patients with chronic Afb and Afl. Before the AA measurement, the comparison between the measurements in supine and prone positions for P waves has been conducted and the experiment gave a result that the supine position is more suitable to measure the atrial excitation. Therefore, the AA was measured in subject's supine position. Clinical potential of AA measurement in MCG is to find an aspect of a reentry circuit and to localize the abnormal stimulation noninvasively. To give useful information about the abnormal excitation, we have developed a method, separative synthetic aperture magnetometry (sSAM). The basic idea of sSAM is to visualize current source distribution corresponding to the atrial excitation, which are separated from the ventricular excitation and the Gaussian sensor noises. By using sSAM, we localized the source of an Afl successfully.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.213-220
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• 2014

Korean magnetoencephalography (MEG) system had been developed and installed to hospital. The Korean MEG system contains helmet-shaped arrays of 152 first-order double relaxation oscillation SQUID (DROS) sensor. As a clinical application we have measured and analyzed evoked responses in patients with functional brain disease by outer stimulation as follows; 1) auditory evoked field in patients with hemifacial spasm, 2) somatosensory evoked fields in patients with tumor. We confirm that neuromagnetic data by Korean MEG system can provide useful information for pre-surgical planning or functional brain research.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.425-430
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• 2016

p-Phenylenediamine (PPD) was synthesized by aromatic amination of p-diiodobenzene (PDIB) using liquid ammonia and Cu-catalysts. The effects of the catalyst, reductant, ammonia quantity and reaction temperature on PPD production were investigated. Cu(I) compounds and Cu powder were selected as catalyst due to a higher selectivity than Cu(II) compounds. As the catalyst quantity increased, rate of PPD production as well as side reaction of aniline decreased with increasing the quantity of ammonia. Reductants such as ascorbic acid, hydrazine and dihydroxyfumaric acid were tested to lower the catalyst loading. The use of reductants resulted in increasing the reaction rate but also increased the amount of aniline The rate of reaction using ascorbic acid or dihydroxyfumaric acid was faster than that using hydrazine. The lowest side reaction of aniline was found in dihydroxyfumaric acid of reductants investigated.