• Tunnel and Underground Space
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• v.18 no.6
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• pp.418-426
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• 2008

A surface blasting method with a single tree face is currently used in Pasir Coal Mine in Indonesia. The single free face is usually the ground surface. This kind of blasting method is easy to use but inevitably causes enormous ground vibrations, which, in turn, can affect the stability of the slopes comprising the various boundaries of the open pit mine. In this regard, we decided to make a specific blasting guideline for the control of found vibrations to ensure the safety of the pit slopes and waste dumps of the mine. Firstly, we derived a prediction equation for the ground vibration levels that could be occurred during blasting in the pits. Then, we set the allowable levels of ground vibrations for the pit slopes and waste dumps as peak particle velocities of 120mm/s and 60mm/s, respectively. From the prediction equation and allowable levels, safe scaled distances were established for field use. The blast design equations for the pit slopes and waste dumps were $D_s{\geq}5\;and\;D_S{\geq}10$ respectively. We also provide several standard blasting patterns for the hole depths of $3.3{sim}8.8m$.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.20-32
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• 2008

The study shows a method called a square-inventory method, which is a better and faster method than scanline survey and window method for an analysis of slope stability. The study area is located in the Changri area, Boeun-Gun, Chungbuk, and consists of many formations of the Okcheon Supergroup. Various types of failure are observed from the phyllite including the rocks in the study area. The physical properties of meta-sedimentary rocks are that minerals of the rocks are composed of microcrystalline quartz and sericite, which are arranged parallel to bedding (or schistosity) and crenulation cleavage. Therefore, such properties affect geotechnical ones of the rock. The slope stability are analyzed by selecting 3 areas, each of which are divided into 2 or 3 slopes of $1m{\times}1m$ area that represent each of 3 investigation sites. The possibility of wedge and toppling failure is very high in all 3 areas by using square-inventory method. Although possibility of plane failure is weak in the investigation site 2, the plane failures are frequently found from the slope of site 2. The bedding (or schistosity) plane and cleavage, another types of discontinuity coexist in meta-sedimentary rocks uulike igneous rocks, and therefore are important factors to be considered together with joint structures in th ε analysis of slope stability.

• Tunnel and Underground Space
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• v.28 no.2
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• pp.156-169
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• 2018

The relationship between the mechanical and textural properties of sedimentary rocks has been studied for decades. However, inconsistencies in the results have arisen from both the inhomogeneity of natural rocks and the difficulties encountered in controlling just one textural factor of interest in each experiment. This work produced artificial sedimentary rocks to enable control of every independent parameter at all times. Their homogeneity lowered the deviation of the results, and thus they produced clearer correlations than for natural rocks. The samples were made by mixing bassanite powder with water and silica sand, which produced rocks consisting of sand and gypsum cement. The effect of grain content and size on mechanical properties such as uniaxial compressive strength, Young's modulus, and seismic velocity was estimated. Increasing grain content lowered the compressive strength but raised Young's modulus and seismic velocity. Overall, grain size did not linearly affect the mechanical properties of the samples, but affected them in some way. In future, these results can be compared and integrated with similar experiments using different cement or grain types. This should allow comparison of the effects of the rock constituents themselves and their interactions, with applicability to all kinds of sedimentary rocks.

• Journal of the Korean Society for information Management
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• v.35 no.3
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• pp.189-214
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• 2018

The purpose of this study is to identify the status and also to develop improvement plans for the children and youth services of the public libraries. To determine the information service status and the librarians' perceptions on the levels of services they provided, the 2016 Korean National Library Statistics System data and the survey results from the children and youth program librarians in the 108 public libraries were analyzed. The analysis revealed the problems such as lack of human resources and budget, shortage of space, and an inflexible program curriculum, which affect the program as a whole negatively. Five suggestions were made to remedy the problems. They are: 1) development of the new programs, which can interest the children and youth and motivate the sense of association among the program participants; 2) increase the number of the programs including the schools and other related organizations nearby region; 3) incorporating the new program formats to enhance the participation; 4) starting the new services explicitly targeted for the information-poor group of people; and 5) soliciting policy-level support for the libraries. In summary, this study made a few suggestions for the libraries ranging from planning the programs to requesting assistance from the national as well as the regional governments.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.368-374
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• 2020

Journaling file systems (JFS) manage changes of file systems not yet committed in a data structure known as a journal to restore the file system in the event of an unexpected failure. Extra write operations required for journaling negatively affect the performance of JFS. The high-performance and byte-addressable non-volatile memory (NVM) was expected to easily mitigate these performance problems by providing NVM space as journal storage. However, even with such non-volatile memory technologies, performance problems still arise due to scalability problems inherent in processing transactions of JFS. To solve this problem, we proposes a technique for processing file system transactions for scalable performance. To this end, lock-free data structures are used and multiple I/O requests are allowed to simultaneously be processed on high-performance storage devices with multiple I/O channels. We evaluate the file system with the proposed technique by comparing the original ext4 file system and the recent proposed NVM-based journaling file system on a multi-core server, and experimental results show that our file system has better performance (up-to 2.9/2.3 times) than the original ext4 file system and the recent NVM-based journaling file system, respectively.

• Journal of Distribution Science
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• v.15 no.2
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• pp.101-109
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• 2017

Purpose - Previous studies related to emotional labor of salespeople have mainly focused on identifying the antecedents of emotional exhaustion and turnover intention and exploring the mitigating effects salespeople's motivation on emotional exhaustion and turnover intention. They also demonstrates that there are different roles for moderating in social support, which means mental/physical support related to the job in supervisors, colleagues and organizations. The purpose of this paper is to investigate how service employees' surface acting affect turnover intention through emotional exhaustion. Another important objective of this paper is to investigate whether perceived social support moderates 1) the relationship between surface acting and emotional exhaustion 2) the relationship between emotional exhaustion and turnover intention. Research design, data, and methodology - To test the hypotheses, we collected the data from Korean insurance company sales employees. A total of 235 responses were received, from which 220 usable responses were obtained after list-wise deletion. Working with a sample of 220 responses, structural equation modeling was employed to empirically test research hypotheses(

The relationship between surface acting and emotion exhaustion,

The relationship between emotion exhaustion and turnover intention,

The moderating effect of perceived social support(PSS) on the relationship between surface acting and emotion exhaustion, and

The moderating effect of perceived social support(PSS) on the relationship between emotion exhaustion and turnover intention. SPSS 22.0 and AMOS software were used in these data analysis. Results - The service employees' surface acting was positively related to the emotional exhaustion; in turn, the service employees' feelings on emotional exhaustion are positively related to turnover intention. In addition, Perceived Social Support significantly moderated the relationship between surface acting and emotional exhaustion. However, perceived social support has a non-significant moderating effect on the path from emotional exhaustion to turnover intention. On the basis of these results, the following conclusion can be drawn. First, distribution service companies will be needed the administrative efforts to offer counseling programs and space to provide their members with enough rest in experiencing psychological pain due to the salespeople's surface acting. Also, it is necessary for distribution service companies to identify and share the examples of successfully solving emotional exhaustion caused by salespeople's surface acting.

• Journal of the Korean Society for information Management
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• v.30 no.4
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• pp.93-110
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• 2013

During the last decade, increasing use of technology that facilitates information access has changed academic library services. The emergence of information commons is one of the key changes. Most previous studies on information commons have focused on its conception and role. Whereas, considering information commons as a spatial service, this study aims to examine the influence of information commons on user traffic patterns within the library and perception of the library. As the information commons grew into main library service space and facility, it is necessary to explore what influences information commons have on the behavior and recognition of users. Two methods were used. First, observation method was used to record traffic pattern and user behavior. Second, twenty undergraduates and twelve graduates were interviewed regarding the use and recognition of the information commons and the library. The results of the study show that the traffic patterns were different between undergraduate students and graduate students; the location and structure of facilities influences their movement and behaviors; and the recognition of information commons tends to affect the perception of the entire library. The findings may help librarians improve and plan for library spaces to meet user demands.

• Tunnel and Underground Space
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• v.24 no.2
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• pp.176-186
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• 2014

Roughness, aperture and filling material of rock joint are widely considered to affect the hydraulic characteristics of joint. Among these factors, in this study, the joint roughness was examined with artificial joint profiles generated by Monte Carlo simulating on the original profiles suggested by Barton and Choubey(1977). Original profiles and revised profiles were combined to establish flow channel models, in which the hydraulic characteristics were analyzed numerically on the basis of minimum aperture changes and flow channel shapes. Maximum flow rate was identified at the growing point of flow area after passing through minimum aperture generated by the two profiles, and it was resulted that maximum flow rate is inversely proportional to minimum aperture. Maximum flow rate per unit area showed different values because flow channel shapes and minimum aperture locations are different in each model. In flow channel, mechanical aperture showed approximately 1.07 ~ 3.00 times larger than hydraulic aperture. In this study, mechanical and hydraulic aperture were concluded to be closely related to $A_i$ value, and their relations can be denoted by $e_m=0.519A^{0.7169_i}$ and $e_h=0.6182A^{0.239}_i$, respectively.

• Journal of Korean Society of Transportation
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• v.18 no.5
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• pp.7-16
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• 2000

This paper is focused on verifying time-space repetition of the highway accident and finding the their causes and deterrents. We classify all months into several seasonal groups, develop the model for each seasonal group and analyze the results of these models for Joong-bu highway. The existence of seasonal effect is verified by the analysis or self-organizing map and the accident indices. Agglomerative hierarchical cluster analysis which is used to decide the seasonal groups in accordance with accident patterns, winter group, spring-fall group. and summer group. The accident features of winter group are that the accident rate is high but the severity rate is low. while those of summer group are that the accident rate is low but the severity rate is high. Also, the regression model which is developed to identify the accident Pattern or each seasonal group represents that the season-related factors, such as the amount of rainfall, the amount of snowfall, days of rainfall, days of snowfall etc. are strongly related to the accident pattern of evert seasonal group and among these factors the traffic volume, amount of rainfall. the amount of snowfall and days of freezing importantly affect the local accident Pattern. So, seasonal effect should be considered to the identification of high-risk road section. the development of descriptive and Predictive accident model, the resource allocation model of accident in order to make safety management plan efficient.

• Spatial Information Research
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• v.21 no.1
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• pp.63-73
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• 2013

Geographic features are reflected in satellite images, which contain characteristic elements. Information on changes can be obtained through a comparison of images taken at different times. If multi-temporal images can be classified through the use of an unsupervised method, this is likely to improve the accuracy of image classification and contribute to various applications. A rule-based image classification algorithm for automatic processing without human involvement has been developed, but it must be verified that its results are not affected by imperfect elements. In this study, Landsat images of Jeju Island were used to carry out a rule-based image classification. The application results were examined for complex cases, including the presence of clouds in the images, different photographed times, and the type of target area, such as city, mountain, or field. The presence of clouds did not affect calculations, and appropriate classification rules were applied, depending on the different photographed times. The expansion of the urban areas of Jeju and the increase of facilities such as vinyl greenhouses in Seoguipo were identified. Furthermore, space information changes and accurate classifications for Jeju Island were obtained. With the goal of performing high-quality unsupervised classifications, measures to generalize and improve the methods employed were searched for. The findings of this study could be used in time-series analyses of images for various applications, including urban development and environmental change monitoring.