• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.617-631
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• 2019

In the four-step demand model, a gravity mode is used most commonly at the trip distribution stage. The purpose of this study was to develop a new friction factor that can express the accessibility property as a single friction factor to compensate for the variable limits of the gravity model parameters (travel time, travel cost). To derive a new friction factor, a new friction factor was derived using the space syntax that can quantify the characteristics of the urban space structure, deriving the link-unit integration degree and then using the travel time and travel distance relationship. Calibration of the derived friction factor resulted in a similar level to that of the existing friction factor. As a result of verifying the various indicators, the explanatory power was found to be excellent in the short - and long - distance range. Therefore, it is possible to derive and apply the new friction factor using the integration index, which can complement the accessibility beyond the limit of the existing shortest distance, and it is believed to be more advantageous in future utilization.

• Journal of Construction Engineering and Project Management
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• v.9 no.2
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• pp.1-24
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• 2019

Poor project performance has been noted as the bane in the construction industry globally. This paper sought to investigate, by way of literature, the performance patterns of construction projects in Kenya since independence (1963-2018). This was informed by reports of undesirable project performance in the industry. This descriptive study used available studies previously done in this subject area. In sum, literature is replete with evidence on a myriad of challenges facing the execution of projects. The study established that generally, the project performance is poor and has assumed a chronic trajectory spanning over five decades. On average, the findings reveal that 35-60% of projects initiated in Kenya face cost overruns while time overrun is most severe with 35-73% projects overrunning their schedule. In addition, the findings problematize the issue of plurality of performance measurement regimes in the construction industry. Here, it was observed that no singular construct exists to objectively measure the various facets that constitute the 'health' of a project. This paper has contributed to the body of knowledge by examining the performance patterns in Kenya for over fifty years while at the same time identifying the bottlenecks inherent in projects execution. Importantly, the conceptual performance efficiency framework derived in the current study presents a paradigm shift in the monitoring and evaluation of projects. To this end, an in-depth analysis is recommended on the interaction of efficiency enablers in the buildup of performance efficiency index (PEI). Similarly, a further inquiry is recommended on the integration and impact of the proposed framework in the management of projects.

• Korean Journal of Remote Sensing
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• v.35 no.4
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• pp.517-534
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• 2019

In abrupt fire disturbances, high quality images suitable for wildfire damage assessment can be difficult to acquire. Quantifying wildfire burn area and severity are essential measures for quick short-term disaster response and efficient long-term disaster restoration. Planetscope (PS) imagery offers 3 m spatial and daily temporal resolution, which can overcome the spatio-temporal resolution tradeoff of conventional satellites, albeit at the cost of spectral resolution. This study investigated the potential of augmenting PS imagery by integrating the spectral information from Sentinel-2 (S2) differenced Normalized Burn Ratio (dNBR) to PS differenced Normalized Difference Vegetation Index (dNDVI) using histogram matching,specifically for wildfire burn area and severity assessment of the Okgye wildfire which occurred on April 4th, 2019. Due to the difficulty in acquiring reference data, the results of the study were compared to the wildfire burn area reported by Ministry of the Interior and Safety. The burn area estimates from this study demonstrated that the histogram-matched (HM) PS dNDVI image produced more accurate burn area estimates and more descriptive burn severity intervals in contrast to conventional methods using S2. The HM PS dNDVI image returned an error of only 0.691% whereas the S2 dNDVI and dNBR images overestimated the wildfire burn area by 5.32% and 106%, respectively. These improvements using PS were largely due to the higher spatial resolution, allowing for the detection of sparsely distributed patches of land and narrow roads, which were indistinguishable using S2 dNBR. In addition, the integration of spectral information from S2 in the PS image resolved saturation effects in areas of low and high burn severity.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.1
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• pp.23-28
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• 2019

The Titanium oxide ($TiO_2$) is an attractive ceramic material which shows non-toxic, high refractive index, catalytic activity and biocompatibility, and can be fabricated at a low cost due to its high chemical stability and large anisotropy. $TiO_2$ nanoparticles have been prepared by sol-gel method. The pH of solution can affect the $TiO_2$ crystallinity during the formation of nanoparticles. The prepared nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy in order to investigate their structural and photoluminescence properties. Through these analysis, the size of $TiO_2$ nanoparticles were found to be smaller than 5 nm. As the crystallinity of the nanoparticles increased, the emission of PL in the 550 nm region increased. Therefore, luminescence characteristics can be improved by controlling the crystallinity of the $TiO_2$ nanoparticles.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.23-33
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• 2004

Because of a rapid growth of internet environment, it is also fast increasing to exchange message using e-mail. But, despite the convenience of e-mail, it is rising a currently bi9 issue to waste their time and cost due to the spam mail in an individual or enterprise. Many kinds of solutions have been studied to solve harmful effects of spam mail. Such typical methods are as follows; pattern matching using the keyword with representative method and method using the probability like Naive Bayesian. In this paper, we propose a classification method of spam mails from normal mails using Support Vector Machine, which has excellent performance in pattern classification problems, to compensate for the problems of existing research. Especially, the proposed method practices efficiently a teaming procedure with a word dictionary including a generated index by the n-Gram. In the conclusion, we verified the proposed method through the accuracy comparison of spm mail separation between an existing research and proposed scheme.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.599-610
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• 2021

Early detection of small concrete crack or reinforcement corrosion is necessary for Structural Health Monitoring (SHM). Global vibration based methods are advantageous over local methods because of simple equipment installation and cost efficiency. Among vibration based techniques, FRF based methods are preferred over modal based methods. In this study, a new coupled method using frequency response function (FRF) and proper orthogonal modes (POM) is proposed by using the dynamic characteristic of a damaged beam. For the numerical simulation, wave finite element (WFE), coupled with traditional finite element (FE) method is used for effectively incorporating the damage related information and faster computation. As reported in literature, hybrid combination of wave function based wave finite element method and shape function based finite element method can addresses the mid frequency modelling difficulty as it utilises the advantages of both the methods. It also reduces the dynamic matrix dimension. The algorithms are implemented on a three-dimensional reinforced concrete beam. Damage is modelled and studied for two scenarios, i.e., crack in concrete and rebar corrosion. Single and multiple damage locations with different damage length are also considered. The proposed methodology is found to be very sensitive to both single- and multiple- damage while being computationally efficient at the same time. It is observed that the detection of damage due to corrosion is more challenging than that of concrete crack. The similarity index obtained from the damage parameters shows that it can be a very effective indicator for appropriately indicating initiation of damage in concrete structure in the form of spread corrosion or invisible crack.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.4
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• pp.61-75
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• 2021

Roadside greenery in the city is not only a means of reducing fine dust, but also an indispensable element of the city in various aspects such as improvement of urban thermal environment, noise reduction, ecosystem connectivity, and aesthetics. However, in studies dealing with the effect of reducing fine dust through trees in existing urban spaces, microscopic aspects such as the adsorption effect of plants were dealt with, structural changes such as the width of urban buildings and streets, and the presence or absence of trees, Impact studies that reflect the actual form of In this study, the effect of greenery composition applicable to urban space on PM2.5 was simulated through the microclimate epidemiologic model ENVI-met, and field measurements were performed in parallel to verify the results. In addition, by analyzing the results of fine dust background concentration, wind speed, and leaf area index, the sensitivity to major influencing variables was tested. As a result of the study, it was confirmed that the fine dust reduction effect was the highest in the case with a high planting amount, and the reduction effect was the greatest at a low background concentration. Based on this, the cost of planting street green areas and the effect of reducing PM2.5 were compared. The results of this study can contribute as a basis for considering the effect of pedestrian space on air quality when planning and designing street green spaces.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.652-665
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• 2022

Difference found in the degree of activating commercial space in subway stations is getting bigger and bigger. With an assumption that commercial space in stations demands public management, this study is aimed to figure out factors that influence the activation of commercial space in stations. To address the goal, the AHP was adopted to draw the importance of activation indexes. Applying the importance of activation indexes drawn, this study analyzed 260 stations located in Seoul regarding the ranking of activation of the stations and also the characteristics of each individual region and index. According to the findings of analysis, there exists a great gap in the degree of activation by either life zones or autonomous districts, and factors having big influence over activation are found to be floating population and the number of passengers getting in or out.

• Clinics in Shoulder and Elbow
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• v.25 no.2
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• pp.129-139
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• 2022

Background: Several therapeutic methods have been proposed for frozen shoulder syndrome. These include suprascapular nerve block, a simple and cost-effective technique that eliminates the need for nonsteroidal anti-inflammatory drug therapy. Methods: This was a clinical trial that included patients with unilateral shoulder joint stiffness. Patients were divided into three groups: those treated with isolated physiotherapy for 12 weeks (PT group), those treated with a single dose intra-articular injection of corticosteroid together with physiotherapy (IACI group), and those treated with a suprascapular nerve block performed with a single indirect injection of 8-mL lidocaine HCL 1% and 2 mL (80 mg) methylprednisolone acetate together with physiotherapy (SSNB group). The variables assessed were age, sex, side of involvement, dominant limb, presence of diabetes, physical examination findings including erythema, swelling, and muscle wasting; palpation and movement findings; shoulder pain and disability index (SPADI) score; and the visual analog scale (VAS) score pre-intervention and at 2-, 4-, 6-, and 12-week post-intervention. Results: Ninety-seven patients were included in this survey (34 cases in the PT group, 32 cases in the IACI group, and 31 cases in the SSNB group). Mean age was 48.55±11.06 years. Fifty-seven cases were female (58.8%) and 40 were male (41.2%). Sixty-eight patients had a history of diabetes (70.1%). VAS and SPADI scores and range of mototion degrees dramatically improved in all cases (p<0.001). Results were best in the SSNB group (p<0.001), and the IACI group showed better results than the PT group (p<0.001). Conclusions: Suprascapular nerve block is an effective therapy with long-term pain relief and increased mobility of the shoulder joint in patients with adhesive capsulitis.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.1003-1012
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• 2022

The horizontal force transfer to the turbine and substructure of a wind power generation system is a very important factor in maintaining the safety of the system, but it is inevitably vulnerable to large-scale coastal disasters such as earthquakes and typhoons. Wind power generation systems built on the coast or far offshore are very disadvantageous in terms of economic feasibility due to an increase in initial investment cost because a more robust design is required when installed in areas vulnerable to coastal disasters. In this study, the GIS method was used to select the optimal site for a wind farm from the viewpoint of reducing the risk of coastal disasters. The current status of earthquakes in the West and South Seas of Korea, and the path and intensity of typhoons affecting or passing through the West and South Seas were also analyzed. Accordingly, the optimal offshore wind farm site with the lowest risk of coastal disasters has been selected and will be used as basic research data for offshore wind power projects in the region in the future.