• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.19-37
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• 2024

Rockbolts are the primary-supports in NATM tunnels and are widely used at tunnel construction sites. Among the rockbolts methods applied in domestic tunnel design, fully grouted rockbolts are the most representative and frequently used. Fully grouted rockbolts exhibit relative behavior between the bolt and the ground due to the grout material. However, during numerical analysis for tunnel design, fully grouted rockbolts are often modeled in a way that does not reflect their behavior characteristics. This may result in underestimating or overestimating the force of the supports. Based on a literature review, it was analyzed that fully grouted rockbolts are modeled using truss element or cable element. To analyze the effect of grout properties of cable elements on rockbolts behavior, this paper compared the behavior of rockbolts in two models: one estimating grout properties based on rockbolt pull-out test data, and another assuming complete adhesion between the rockbolts and the ground by applying large grout properties. Under identical tunnel conditions, the numerical analysis was conducted by modeling the fully grouted rockbolts differently using truss and cable elements, and the tunnel behavior was analyzed. The research results suggest that modeling fully grouted rockbolts as a function of the interface effect between the bolts and the ground, specifically considering grout, is desirable. The use of pull-out test data to simulate the behavior of actual fully grouted rockbolts was considered as a valid approach.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.95-108
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• 2022

The increase in the use time of tunnel users due to the lengthening of the road tunnel may increase the evacuation time in case of fire, resulting in a large number of casualties. In order to reduce the casualties caused by fire, the "Road Tunnel Design Manual, Part 6 Tunnel" and "Road Tunnel Disaster Prevention Facility Installation and Management Guidelines" stipulate that ventilation facilities should be installed along with the extension of the tunnel. The ventilation system design factor considers the wind speed of the external natural wind to be at least 2.5 m/s, and it is applied upward according to the characteristics of the tunnel. As a result of analyzing the five-minute average wind speed data in the Daegwallyeong region for the past 6 years, it was analyzed that 15.8% of the windy days were winds of 10 m/s or more, and the maximum was 20 m/s. Therefore, in this study, when a fire occurs in a tunnel, the pattern of natural wind flowing into the tunnel and the backlayering distance of the tunnel fire smoke according to the maximum wind speed were analyzed. As a result, it was analyzed that a backflow of up to 490 m occurs when a gust of 20 m/s blows.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.10
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• pp.983-990
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• 2010

Reduction of acoustic loads of space launch vehicles can be achieved by acoustic absorbers satisfying strict cleanness requirements. This limited the use of general porous materials and requires non-porous sound absorbers. Micro-perforated panel absorbers(MPPA) is one of promising sound absorbers satisfying the cleanness requirement for launch vehicles. However, its applicability was limited to low sound pressure levels according to the acoustic impedance model of micro-perforated panels. In this paper the applicability of micro-perforated panel absorbers at high incident sound pressure was investigated in experimental ways. The absorption characteristics of a micro-perforated panel absorber was simulated according to its design variables, e.g., minute hole diameters and aperture ratios. It was shown that optimal design can be readily done by using proposed design charts. Experiments were conducted to measure acoustic properties of the designed micro-perforated panel absorbers. The results showed that acoustic resistance increases rapidly as incident sound pressure level does but change of acoustic reactance can be neglected in a practical point of view. This caused the decrease of peak value of absorption coefficient at high incident sound pressure level, but the amount of reduction can be accepted in practice. The major advantage of the micro-perforated panel absorber(wide absorption bandwidth) was still kept at high sound pressure level.

• Korean Journal of Human Ecology
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• v.8 no.2
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• pp.327-337
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• 1999

Primitive men's primordial formative activity derives from incarnation contained in intensive vitality and strong creativity mind. The trend of modern fashion requiring the boundless imagination can be called that it, just, itself, has something in common with basic spiritual activity that primitive men had. What is concerning how modern fashion designers have developed formative language through enchanting primitive art is as follows. 1. The nature's mysterious power appears to be transformed into personified image. The incarnation for acquiring beauty, power, prestige of genius appears in the form of personification, making use of mask in modern fashion. 2. As for primitive men, the whole universe has a potentiality as a symbol. The symbolism of primitive art based on religion and myth appears in modern art as the form of presenting oppositional objects together in one space. 3. Primitive art is the purest form and the most unpolluted. This shows the natural quality being assimilated into nature, which is expressed in modern fashion as intensity, free-spirit, simplicity, etc. 4. The primitive men's anxiety to the outside world appears as impulse. The geometrical form of primitive art occurred in the shape of impulse appears in expressional form of modern fashion. 5. The real existence in primitive art inducing real materials and objects, in themselves, into formative world appears in modern art in the way of expression such as repetition, enlargement, exact reproduction.

• Korean Journal of Environment and Ecology
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• v.33 no.2
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• pp.237-251
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• 2019

This study evaluated the ecological value of waterside parks by investigating the animal distribution and ecological feature in 92 waterside parks and analyzed the change of ecological awareness by users and non-users of waterside parks through ecological education and promotion based on the investigation results. The result confirmed inhabitation of various animals including 9 endangered species (Pernis ptilorhynchus orientalis, Accipiter soloensis, Falco subbuteo, Charadrius placidus, Felis bengalensis euptilura, Lutra lutra, Kaloula borealis, Polyphylla laticollis manchurica, and Leptalina unicolor) in waterside parks. Although waterside parks were constructed to be hydrophilic areas for human use, some of them with high natural characteristics are valued as biological habitat. We investigated user status in 5 areas (Daejeon, Sejong, Cheongju, Kongju, and Buyeo) located at Guem river basin to evaluate people's perception of waterside parks and carried out the ecological education and promotion based on the investigation result. The survey of 200 people showed that there were more users of waterside parks than non-users and that people in their 40's showed the highest use rate. The use frequency of waterside parks located in Daejeon and Cheongju was lower than in other areas (Sejong, Kongju, and Buyeo). We considered it was because Daejeon and Cheongju were urban areas and had relatively more leisure areas such as sports facilities and cafe than other areas, and thus the residents had a lower reliance on waterside parks. Moreover, users used waterside parks more frequently when they were nearer to users' residence. It is because most users perceived waterside parks as the leisure sports facility and thus preferred them to be within walking distance. The users' perception of waterside parks as the ecological space "to be preserved" increased after the ecological education and promotion. The change of the perception was higher among users (80%) than non-users (38%). Therefore, ecological education and promotion were potentially more effective to people who user waterside parks and thus had a higher understanding of the characteristics and specification. In conclusion, 1) although waterside parks were constructed for human use, some parts had high ecological value for the distribution of endangered species and outstanding natural beauty, and 2) it is necessary to change the perception of waterside parks from the hydrophilic attribute to the conservation attribute. Such change of perception would contribute to establishing waterside parks that feature both hydrophilic and conservation attributes in the management or upgrading plan of waterside parks in the future.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.2
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• pp.83-94
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• 2020

Busan Metropolitan City, a research site of this study, was promoted to a metropolitan city in 1995 with the implementation of the local autonomy system, and the overall change was made as it absorbed the surrounding areas to address the shortage of population and space. Twenty-five years after the introduction of the local autonomy system, it is necessary to diagnose whether balanced development of the entire city is being made in accordance with the reorganization of the metropolitan city in terms of spatial structure. In this study, changes in spatial structure and regional characteristics were analyzed by applying population potential, which means potential for future spatial interaction, in time and space. According to the analysis, the development was taking place around the center area and the sub-center established by the urban master plan, but Gangseo-gu and Gijang-gun, which were incorporated in the past, remained stagnant. In addition, it was shown that the spatial expansion of the city was suppressed by the green belt surrounding the city. However, in other regions where the green belt is located, the city has been expanded, which is different from Gijang-gun or Gangseo-gu, which was incorporated into the metropolitan city. Therefore, the cause of the decline in incorporated areas should not be limited to the institutional dimension of land use regulation. Growth management and balanced development plans will be necessary for the development of declining old downtowns and underdeveloped incorporated areas.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.80-86
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• 2012

This study is for figuring out a possibility of realization of the thermal protection system(TPS) for temporary use under high temperature condition and improving a design of the future TPS. On this purpose, environmental condition of the system has been simplified: the boundary conditions consist of a internally heating surface and a externally heated surface which is simulating the external high temperature condition. Configuration of the system is simplified as a hexahedon. Melting characteristics of the phase change material(PCM) and air temperature variation of TPS with or without connector have been numerically analyzed and compared. As a result of numerical analysis, the heat from the internally heated surface could not be effectively transferred. Therefore, temperature of inner space has been increased.

• Journal of architectural history
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• v.2 no.1 s.3
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• pp.25-41
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• 1993

This study was made to analyze the housing adjustment phenomenon in the first half of Chosun Dynasty by applying Microsociological approach. By reviewing the housing adjustment theory of Morris and Winter, research model for the period was developed in terms of socioeconomic characteristics, normative housing deficit (=cultural norm-housing condition+family norm), constraints, behavioral propensities, and housing adjustment mechanism with the following results : 1. In the first half of Chosun Dynasty the size of the house, the house site and decorating items were specified by law (cultural norm) according to the social status. Although the law was constraints for the housing phenomenon, it was not applied universally. Frequantly the law was violated by the upper class. By the middle of the Dynasty the family norm became more important for the housing phenomenon than the cultural norm. 2. Efforts were made to practice the Confucianism as a cultural norm in the first half of Chosun Dynasty At that time Husband-Living-in-Wife's-House was more popular than Wife-Living-in-Husband's-House. Because the customs were against the Confucianism, the latter was encouraged by law. But it did not change. Instead a compromised system became popular in the middle of the Dynasty. The house shrine was practiced to increase the symbolism of the family, which, in turn, exerted influences in deciding the housing site (cultural norm). These cultural norm was not accepted as the family norm untill the second half of the Dynasty. These trends forced the man and woman use separate areas of the house, and formulated a hierarchic positions within a house. 3. It was shown that the settlement of Confucianism as a family norm was closely related to the popularization of the Ondol system in the house, which functioned as one of the behavioral propensities to encourage diversity of space for many purposes. Though the Ondol system was accepted as a useful heating system earlier, this became more popular in the middle of the Dynasty because the housing pattern with Ondol fitted very well with a large family system with patriarchism. Ondol system for one or two rooms substituted Ondol for all rooms in the second half of the Dynasty. 4. From the beginning of the Dynasty housing adjustment of the family was determined by the social status and by law (cultural norm). Within this cultural norm each family decided its adjustment mechanism according to its economic ability (family norm). Family norm was more important factor than the cultural norm to determine the micro-space pattern in the house. But this period witnessed the formations of new conditions by the ruling class's efforts to implement new ethics for hierarchy and sexual discrimination. According to these conditions the Confucianism overruled the family norm in the later period.

• The Journal of Bigdata
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• v.6 no.1
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• pp.1-12
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• 2021

The rapid growth of mobile-based online shopping and the appearance of untact business initiated by COVID-19 has led to an explosive increase in demand for logistics services such as delivery services. In order to respond to the rapidly growing demand, most logistics and distribution companies are working to improve customer service levels through the establishment of a full-filament center in the city center. However, due to social factors such as high land prices and traffic congestion, it becomes more difficult to establish the logistics facilities in the city center. In this study, it has been proposed the way to choose the candidate locations for the shared distribution centers among the space nearby the tall-gate which can be idle after the smart tolling service is widely extended. In order to evaluate the candidate locations, it has been evaluated the centralities of all candidates using social network analysis (SNA). To understand the result considering the characteristics of centrality, the network structure was regenerated based on the distance and the traveling time, respectively. It is possible to refer the result of evaluation based on the cumulative relative importance to choose the best set of candidates.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.209-222
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• 2024

The Earth Pressure Balance (EPB) shield Tunnel Boring Machine (TBM) is widely used for underground tunnel construction for its advantages, such as eliminating the need for additional facilities compared to the slurry shield TBM, which requires Slurry Treatment Plant (STP). During EPB shield TBM excavation, a soil conditioning technique is employed to enhance the physical properties of the excavated soil by injecting additives, thus broadening the range of applicable ground conditions to EPB shield TBMs. This study explored the use of xanthan gum, a type of biopolymer, as an alternative to the commonly used polymer additive. Biopolymers, derived from biological sources, are fully biodegradable. In contrast to traditional polymers such as polyacrylic acid, which contain environmentally harmful components, xanthan gum is gaining attention as an eco-friendly material due to its minimal toxicity and environmental impact. Test conditions with similar workability were established through slump tests, and the rheological characteristics were assessed using a laboratory pressurized vane shear test apparatus. The experiments demonstrated that, despite exhibiting similar workability, the peak strength in the flow curve decreased with increasing the content of xanthan gum. Consequently, a correlation between the xanthan gum content and peak strength was established. Replacing the traditional polymers with xanthan gum could enable stable EPB shield TBM operation by reducing equipment load, in addition to offering environmental benefits.