• Journal of Korean Neurosurgical Society
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• v.30 no.9
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• pp.1079-1085
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• 2001

Objective : We analysed various surgical approaches and surgical results of 28 middle cranial base tumors for the purpose of selecting optimal surgical approach to the middle cranial base tumor. Methods : In this retrospective review, 28 patients, including 16 meningioma, 6 trigeminal neurinoma, 2 pituitary adenoma, 2 craniopharyngioma, 1 facial neurinoma, and 1 metastatic tumor, underwent surgical treatment using skull base technique. Of theses, 16 tumors were mainly confined to middle cranial fossae, 5 tumors with extension into both anterior and middle fossa, and 7 tumors with extension into both middle and posterior fossa. Tumors that confined to the middle cranial fossa or extended into the anterior cranial fossa were operated with modified pterional, orbitozygomatic or Dolen'c approach, and tumors that extended into the posterior cranial fossa were operated with anterior, posterior or combined transpetrosal approach. Completeness of tumor resection, surgical outcome, postoperative complication, and follow up result were studied. Results : Total tumor removal was achieved in 9 tumors of 10 tumors that did not extended to the cavernous sinus, and was achieved in 7 tumors of 8 tumors that extended to the lateral wall of the cavernous sinus. Of 10 tumors that extended to the venous channel of the cavernous sinus, only 2 were removed totally. Surgical outcome was excellent in 14 patients, good in 10, fair in 2 and poor in 2. There were no death in this series. Dumbell type tumor which extended into both middle and posterior fossae showed tendency of poor prognosis as compared with tumors that confined middle cranial fossa and extended into both anterior and middle cranial fossa. Postoperative dysfunctions were trieminal hypesthesia in 3, oculomotor nerve palsy in 2, abducens nerve palsy in 2, hemiparesis in 2, cerebellar sign in 1, facial palsy in 1 and hearing impairment in 1. Conclusion : Based on our findings and a review of the literature, we conclude that, when selecting the surgical approach to the middle cranial fossa tumors, the most important factors to be considered were exact location of the tumor mass and existence of the cavernous sinus invasion by tumor mass. We recommend modified pterional or orbitozygomatic approach in cases with tumors located anterior and middle cranial base, without cavernous sinus invasion. In cases with tumors invading into cavernous sinus, we recommend Dolen'c or orbitozygomatic approach. And in lateral wall mass and the cavernous sinus, it is preferred to approach the tumor extradurally. For the tumor involing with middle fossa and posterior fossa(dumbell type) a combined petrosal approach is necessary. In cases with cavernous sinus invasion and internal carotid artery encasement, we recommend subtotal resection of the tumor and radiation therapy to prevent permanent postoperative sequele.

• Journal of Life Science
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• v.21 no.7
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• pp.1032-1038
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• 2011

Recently identified Ciona intestinalis voltage sensor-containing phosphatase (Ci-VSP) consists of an ion channel-like transmembrane domain (VSD) and a phosphatase-like domain. Ci-VSP senses the change of membrane potential by its VSD and works as a phosphoinositide phosphatase by its phosphatase domain. In this study, we present the construction of His-tagged phosphatase-like domain of Ci-VSP, its recombinant expression and purification, and its enzymatic activity behavior in order to examine the biochemical behavior of phosphatase domain of Ci-VSP without interference. We found that Ci-VSP(248-576)-His can be eluted with an elution buffer containing 25 mM NaCl and 100 mM imidazole during His-tag purification. In addition, we found the proper measurement condition for kinetics study of Ci-VSP(248-576)-His against p-nitrophenyl phosphate (pNPP). We measured the kinetic constant of Ci-VSP(248-576)-His at $37^{\circ}C$, pH 5.0 or 5.5, under 30 min of reaction time, and less than $2.0\;{\mu}g$ of protein amount. With these conditions, we acquired that Ci-VSP(248-576)-His has $K_m$ of $354{\pm}0.143\;{\mu}M$, $V_{max}$ of $0.0607{\pm}0.0137\;{\mu}mol$/min/mg and $k_{cat}$ of $0.359{\pm}0.009751\;min^{-1}$ for pNPP dephosphorylation. Therefore, we produced a pure form of Ci-VSP(248-576)-His, and this showed a higher activity against pNPP. This purified protein will provide the road to a structural investigation on an interesting protein, Ci-VSP.

• Journal of Life Science
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• v.25 no.8
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• pp.953-959
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• 2015

Optogenetics is the combination of optical and molecular strategies to control designated molecular and cellular activities in living tissues and cells using genetically encoded light-sensitive proteins. It involves the use of light to rapidly gate the membrane channels that allows for ion movement. Optogenetics began with the placing of light-sensitive proteins from green algae inside specific types of brain cells. The cells can then be turned on or off with pulses of blue and yellow light. Using the naturally occurring algal protein Channelrhodopsin-2 (ChR2), a rapidly gated light-sensitive cation channel, the number and frequency of action potentials can be controlled. The ChR2 provides a way to manipulate a single type of neuron while affecting no others, an unprecedented specificity. This technology allows the use of light to alter neural processing at the level of single spikes and synaptic events, yielding a widely applicable tool for neuroscientists and biomedical engineers. An improbable combination of green algae, lasers, gene therapy and fiber optics made it possible to map neural circuits deep inside the brain with a precision that has never been possible before. This will help identify the causes of disorders like depression, anxiety, schizophrenia, addiction, sleep disorder, and autism. Optogenetics could improve upon existing implanted devices that are used to treat Parkinson’s disease, obsessive-compulsive disorder and other ailments with pulses of electricity. An optogenetics device could hit more specific subsets of brain cells than those devices can. Applications of optogenetic tools in nonneuronal cells are on the rise.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4463-4468
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• 2014

To increase the efficiency of a solar module, the development of solar concentrator using a lens or reflection plate is being proceeded actively and the concentrator pursues the a concentration using a lens or an optical device of a concentration rate and designing as a solar tracking system. On the other hand, as the energy density being dissipated as a heat according to the concentration rate increases, the cares should be taken to cool the solar concentrator to prevent the lowering of efficiency of solar cell by the increasing temperature of the solar cell. This study, researched and developed an economical concentrator module system using a low priced reflection optical device. A concentrator was used as a general module to increase the generation efficiency of the solar module and heat generated was emitted by the concentration through the cooling system. To increase the efficiency of the solar concentrator, the cooling system was designed and manufactured. The features of the micro cooling system (MCS) are a natural circulation method by the capillary force, which does not require external power. By using the potential heat in the case of changing the fluid, it is available to realize high performance cooling. The 117W solar modules installed on the reflective plate and the cooling device in the cooling module and the module unit was not compared. The cooling device was installed in the module resulted in a 28% increase in power output.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.35-40
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• 2020

The ballast layers play a key role in distributing and supporting a trainload. On the other hand, it settles down by dynamic train loading due to large void ratios. Consequently, it requires continuous maintenance. In this paper, ballast layers mixed with three types of specially shaped artificial ballast (AB) (Rectangular, Tetrapod, Hexagonal) were modeled by using a two dimensional DEM (Discrete Element Method). Repeated loading tests were performed to evaluate the settlement behavior of the ballast layers. The smallest settlement was observed in the case of the ballast layer mixed with Tetrapod AB than in other cases, according to an analysis of the force transfer routes. In addition, contact force analysis showed that the Tetrapod AB, which has a concave shape, could easily make small and multi-channel force-transfer routes. This means that the stress in the ballast layer by the train loading transferred through the sleeper uniformly was distributed well by the AB. Therefore, the settlement of the ballast layer mixed with the concave-shaped Tetrapod AB could be reduced effectively under a repeated train loading. The effects of a decrease in settlement of the ballast layer highlight the possibility of a maintenance-free ballasted track.

• Clean Technology
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• v.25 no.4
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• pp.283-288
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• 2019

Monodisperse microparticles has been particularly enabling for various applications in the encapsulation and delivery of pharmaceutical agents. The microfluidic devices are attractive candidates to produce highly uniform droplets that serve as templates to form monodisperse microparticles. The microfluidic devices that have micro-scale channel allow precise control of the balance between surface tension and viscous forces in two-phase flows. One of its essential abilities is to generate highly monodisperse droplets. In this paper, a microfluidic approach for preparing monodisperse polycaprolactone (PCL) microparticles is presented. The microfluidic devices that have a flow-focusing generator are manufactured by soft-lithography using polydimethylsiloxane (PDMS). The crucial factors in the droplet generation are the controllability of size and monodispersity of the microdroplets. For this, the volumetric flow rates of the dispersed phase of oil solution and the continuous phase of water to generate monodisperse droplets are optimized. As a result, the optimal flow condition for droplet dripping region that is able to generate uniform droplet is found. Furthermore, the droplets containing PCL polymer by solvent evaporation after collection of droplet from device is solidified to generate the microparticle. The particle size can be controlled by tuning the flow rate and the size of the microchannel. The monodispersity of the PCL particles is measured by a coefficient of variation (CV) below 5%.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.4
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• pp.1-14
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• 2012

A river is defined as the watercourse flowing through its channel, and the mapping tasks of a river plays an important role for the research on the topographic changes in the riparian zones and the research on the monitoring of flooding in its floodplain. However, the utilization of the ground surveying technologies is not efficient for the mapping tasks of a river due to the irregular surfaces of the riparian zones and the dynamic changes of water level of a river. Recently, the spatial information data sets are widely used for the coastal mapping tasks due to the acquisition of the topographic information without human accessibility. In this research, we tried to extract a river from the RapidEye imagery by using the ISODATA(Iterative Self_Organizing Data Analysis) classification algorithm with the two different parameters(NIR (Near Infra-Red) band and NDVI(Normalized Difference Vegetation Index)). First, the two different images(the NIR band image and the NDVI image) were generated from the RapidEye imagery. Second, the ISODATA algorithm were applied to each image and each river was generated in each image through the post-processing steps. River boundaries were also extracted from each classified image using the Sobel edge detection algorithm. Ground truths determined by the experienced expert are used for the assessment of the accuracy of an each generated river. Statistical results show that the extracted river using the NIR band has higher accuracies than the extracted river using the NDVI.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.27-34
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• 2013

This paper deals with the performance anlysis of CCA adaptive equalization algorithm, that is used for reduction of intersymbol interference at the receiving side which occurs in the time dispersive communication channel. Basically, this algorithm is borned for the solving phase unrecovery problem in the CMA equalizer, and the comines the concept of DDA (Decision Directed Algorithm) and RCA (Reduce Constellation Algorithm). The DDA has a stable convergence characteristics in unilevel signal, but not in the number of levels in multilevel signal such as QAM, so it has unstable problem. The RCA does not provide reliable initial convergence. And even after convergence, the equalization noise due to the steady state misadjustment exhibited by it is very high as compared to DDA. For the solving the abovemensioned point, the CCA adaptive eualization alogorithm has borned. In order to performance analysis of CCA algorithm, the recovered signal constellation that is the output of the equalizer, the convergence characteristic by the residual isi and MD (maximum distortion), the SER characteristic are used by computer simulation and it was compared with the DDA, RCA respectively. As a result of simulation, the DDA has superior performance than other algoithm, but it has a convergence unguarantee and unstability in the multilevel signal. In order to solving this problem, the CCA has more good performance than RCA in every performance index.

• Journal of Distribution Science
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• v.7 no.3
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• pp.49-69
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• 2009

With the proliferation of electronic commerce, online transactions have become a norm. Its enormous potential, however, can be truly realized if consumers feel comfortable facing invisible sellers over the Internet, a virtual business channel. Trust has been identified as a key component in many e-Commerce studies. The purpose of this study is to find out which factors play a major role in building buyer trust and how the build-up trust affects buyer's purchase intention in online used car transactions. Based on the information asymmetry, TAM (Technology Acceptance Model), and the trust theory, our research model includes factors such as a buyer's propensity-to-trust, institutional characteristics (inspection and warranty policy), word-of-mouth referral, perceived size, and perceived benefits as independent variables. The model also includes trust as a mediate variable, purchase intention as a dependent variable, and perceived quality risk as a moderate variable. The research model is tested by analyzing 448 sample data gathered from used car websites. The result shows that the trust has significant effects on the online purchase intention, and institutional characteristics have been identified as one of the most significant factors for trust building in used car websites. For those who perceive quality risk high, actual purchasing behavior occurs only when they have trust on the used car websites, indicating that trust plays a vital role as a mediate variable. This study suggests that buyer trust on the used car websites is important to increase buyer's online purchase behavior.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.139-147
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• 2018

This study starts with the consciousness of what should be the public pension service that meets the 4th Industrial Revolution era. To do this, we review the current status of non-facing services of domestic and foreign public institutions, and draw out implications for revitalizing non-facing services of the National Pension over the medium to long term. First, we reviewed the status of non-face-to-face service and the authentication method of the National Pension Service. Next, we reviewed the status of non-facing services in public pension and private agencies in the United States, the United Kingdom, Canada, and Australia. Based on the results of the analysis, we needs to analyze the impact of the 4th Industrial Revolution on the National Pension Service and extract future strategies, to expand channels of non-facing by business, to introduce PinTech as a non-facing authentication method, and to propose a unified service channel through the construction of an internet integrated portal. In the 4th industrial revolution era, it is possible to secure the connectivity of government portal for civil affairs and intelligence and automation introducing artificial intelligence robots.