• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.4 s.44
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• pp.29-42
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• 2005

Total 350 borehole profiles were selected from the database of borehole logs in Seoul, for the site-specific seismic evaluation at two 4km${\times}$4km plain areas. Equivalent-linear site response analyses for the selected 350 sites were conducted based on shear wave velocity (Vs) Profiles, which were determined from the N-Vs correlation established using borehole seismic testing results in the inland areas of Korea. Most sites were categorized as site classes C and D based on the mean Vs to 30 m in depth (Vs30) ranging from 250 to 550 m/s. The she periods of the plains in Seoul ranging between 0.1 and 0.4 sec were significantly lower than those of the western US, from which the site coefficients in Korea were derived. For plains in Seoul, the site coefficients, Fa's and Fv's specified in the Korean seismic design guide, underestimate the ground motion in short-period (0.1-0.5 sec) band and overestimate the ground motion in mid-period (0.4-2.0 sec) band, respectively, because ol the differences in the geotechnical conditions between Seoul and the western US, although the Fa's in several sites overestimate the motion due to the base Isolation effect resulted from the soft layer in soil deposit.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.471-492
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• 2017

The demand and interest in big data analytics are increasing rapidly. The concepts around big data include not only existing structured data, but also various kinds of unstructured data such as text, images, videos, and logs. Among the various types of unstructured data, text data have gained particular attention because it is the most representative method to describe and deliver information. Text analysis is generally performed in the following order: document collection, parsing and filtering, structuring, frequency analysis, and similarity analysis. The results of the analysis can be displayed through word cloud, word network, topic modeling, document classification, and semantic analysis. Notably, there is an increasing demand to identify trending topics from the rapidly increasing text data generated through various social media. Thus, research on and applications of topic modeling have been actively carried out in various fields since topic modeling is able to extract the core topics from a huge amount of unstructured text documents and provide the document groups for each different topic. In this paper, we review the major techniques and research trends of text analysis. Further, we also introduce some cases of applications that solve the problems in various fields by using topic modeling.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.231-237
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• 2016

This research was conducted in order to examine whether the Woodgrab short-wood logging method, most widely used logging method in Korea, is more favorable than other logging methods in terms of productivity and profitability. For the comparative purposes, whole-tree logging methods with cable yarding system using a swing yarder and a tower yarder were evaluated. The productivity and the profitability of the logging operations by the machine types on a L. kaempferi stand were estimated by simulating logging processes based on bucking patterns and the results were compared. As a result, the Woodgrab short-wood logging system showed the most favorable results in terms of skidding productivity and operating cost. On the contrary, the system was the least profitable among the three logging methods. Main reason is that while the system may be beneficial in terms of operation productivity, it is restricted to produce only short logs mainly for low quality raw materials such as pulp, bolts, etc. which are sold at cheap prices.

• Journal of Korean Society of Forest Science
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• v.109 no.1
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• pp.72-80
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• 2020

Two strategies for calculating economic feasibility are the machine rate and cash-flow methods. This study used the cash-flow method to evaluate the economic feasibility of the HAM300 yarding operation for extracting tree length logs in Larix kaempferi forest stands. In financial analysis based on 7-year cash-flow, the net present value and pay-back period method were used. We analyzed two scenarios: operating opportunities (50, 100, 150, and 200 days per year) and productivity change yield (7.5 and 10.5 ㎥/scheduled machine hour: SMH). The analysis indicated that high rates of return on extraction activity investment can be achieved when machines are used for >150 days per year. In addition, improved productivity (10.5 ㎥/SMH) increased financial feasibility compared to current productivity (7.5 ㎥/SMH) when machines were operated for 100 days per year. These results suggest that the appropriateness of HAM300 harvesting depends on the number of annual operating days and productivity.

• Journal of the Korean Society for Library and Information Science
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• v.50 no.3
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• pp.455-490
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• 2016

This study investigated the information behavior and media use of Korean young adults with immigration background, focusing on the influence of their social and cultural context. 11 young adults between 13 and 18 with immigration background participated in the study. The participants provided data via daily logs about information needs, written surveys about media use, and two times of in-depth interviews. The data gathered from these diverse methods were used in analyzing the participants' daily problem situations and attempts to satisfy information needs using media. The information needs of young adults with immigration background in their everyday lives included study, leisure, appearance, self-development, living, and career searching - study and leisure were the most needed information subjects. The young adults who participated in this study were actively using media to solve their information needs. For them, media was an emotional support, a tool to express their own identities, a solution that gives all the answers, and a good companion to spend time with. The proposed strategies about young adults' media use in this study could be used in planning library services for children of families with immigration background.

• Geophysics and Geophysical Exploration
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• v.7 no.3
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• pp.174-183
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• 2004

The knowledge of rock strength is important in assessing wellbore stability problems, effective sanding, and the estimation of in situ stress field. Numerous empirical equations that relate unconfined compressive strength of sedimentary rocks (sandstone, shale, and limestone, and dolomite) to physical properties (such as velocity, elastic modulus, and porosity) are collected and reviewed. These equations can be used to estimate rock strength from parameters measurable with geophysical well logs. Their ability to fit laboratory-measured strength and physical property data that were compiled from the literature is reviewed. While some equations work reasonably well (for example, some strength-porosity relationships for sandstone and shale), rock strength variations with individual physical property measurements scatter considerably, indicating that most of the empirical equations are not sufficiently generic to fit all the data published on rock strength and physical properties. This emphasizes the importance of local calibration before one utilizes any of the empirical relationships presented. Nonetheless, some reasonable correlations can be found between geophysical properties and rock strength that can be useful for applications related to wellhole stability where haying a lower bound estimate of in situ rock strength is especially useful.

• The Journal of Engineering Geology
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• v.30 no.1
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• pp.17-30
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• 2020

An optical televiewer is a geophysical logging device that produces continuous high-resolution full-azimuth images of a borehole wall using a light-emitting-diode and a complementary metal-oxide semiconductor image sensor to provide valuable information on subsurface discontinuities. Recently, borehole imaging logging has been applied in many fields, including ground subsidence monitoring, rock mass integrity evaluation, stress-induced fracture detection, and glacial annual-layer measurements in polar regions. Widely used commercial borehole imaging logging systems typically have limitations depending on equipment specifications, meaning that it is necessary to clearly verify the scope of applications while maintaining appropriate quality control for various borehole conditions. However, it is difficult to directly check the accuracy, implementation, and reliability for outcomes, as images derived from an optical televiewer constitute in situ data. In this study, we designed and constructed a modular fractured borehole model having similar conditions to a borehole environment to report unprecedented results regarding reliable data acquisition and processing. We investigate sonde magnetometer accuracy, color realization, and fracture resolution, and suggest data processing methods to obtain accurate aperture measurements. The experiment involving the fractured borehole model should enhance not only measurement quality but also interpretations of high-resolution and reliable optical imaging logs.

• Journal of Mushroom
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• v.2 no.3
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• pp.157-162
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• 2004

The objectives of this experiment were to study the growth and development of fruiting body of the two Ganoderma lucidum isolates on log of the soft wood Paraserianthes falcataria and the hard wood Shorea sp., and determination of organic germanium and crude ganoderic acid content of the fruiting body produced. The two Ganoderma lucidum isolates used were one Indonesian native (Indonesia isolate) and another isolate was purchased from Fungi Perfecti, USA (commercial isolate). The development and quality of the primordium and fruiting body of the mushroom, in general, were influenced by the isolates used. The types of wood, however, had no effect on the quality of the primordium and fruiting body produced. The Indonesian isolate produced better fruiting body compared to that of the commercial isolate. The development of fruiting body from primordium, however, was low for the two isolates tested. In general, only about one third of the primordium developed further into mature fruiting bodies, except for the commercial isolate grown on the soft wood medium in which more than 60% of the primordium developed into mature fruiting body. Apart from producing normal fruiting body, the commercial isolate also produced an abnormal one, which had a white mature pileus, whereas the normal one was brownish red. The organic germanium concentration of the fruiting body produced on the hard wood, in general, was higher than that of grown on the soft wood. The fruiting body from commercial isolate had higher organic germanium concentration compared to that of Indonesian isolate in both wood types. The two isolates used, however, had almost the same value of the crude ganoderic acid concentration in both types of wood tested. The Indonesian isolate had higher total yield of both organic germanium and crude ganoderic acid of the fruiting body produced compared to that of the commercial isolate.

• Journal of Mushroom
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• v.16 no.3
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• pp.231-235
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• 2018

Arthrographis cuboidea is a wood rot fungus found in soil. It causes disease in repeated cultivation areas of Ganoderma lucidum, which damage the mushroom logs and causes considerable loss of income to mushroom farmers. This study aimed to investigate the physicochemical properties of soil and characteristics of the growth environment such as the temperature of the Ganoderma lucidum cultivated land. The time required for primordia initiation was 12-13 days. In the chromaticity survey, the degree of redness (a) was 19.5 for vinyl, 20.2 for control, and 19.5 for nonwoven. The yellowness index (b) was 12.7 for vinyl, 13.3 for control, and 12.4 for nonwoven. In the study of growth characteristics, in case of no treatment (control), the length and thickness of the pileus were measured as 145.7 mm and 23.6 mm and those of the stipe were 73.9 mm and 11.5 mm, respectively, and the weight was 130 g. Treatment with non-woven fabric resulted in 157 mm and 93.3 mm long and 22.3 mm and 11.9 mm thick pileus and stipe, respectively, and the weight was 164 g. This result indicates that treatment with non-woven fabric is better than no treatment with respect to Ganoderma lucidum growth.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.385-391
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• 2008

Republic of Korea (ROK) log import companies have clustered around In-cheon, Jeon-buk and Busan. This reason related to port for log import. This study analyzed the quantity of Whole imported log transported by port. As the result of analysis, In-cheon port accounted for 56.9% log import, which is the maximum log import port in ROK. Next Bu-san port 20.9%, Gun-san port 17.9%. However, these port have declined the quantity of imported log transported since 2000. Gun-san port and Dong-hae port increased narrow range. The reason of why In-cheon and Bu-san port declined log import and Gun-san and Dong-hae port increased is that a sudden rise in the price of log in 2003, and import of using a container ship increased. In the addition, log import from Far eastern Russia, Germany and America increased through a container ship, however, declined log import through a bulk ship. Most of imported log at In-cheon port are from New zealand and Russia, imported logs at Bu-san port are almost from US and New zealand.