• The Journal of Engineering Geology
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• v.32 no.4
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• pp.671-684
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• 2022

This study verified the stability of a high-strength combined buried pile retaining wall and its applicability in the field. A cast-in-place (C.I.P) retaining wall and the high-strength combined embedded pile retaining wall were compared and analyzed numerically. The numerical analysis assessed the ground behavior and stability (and thus field applicability) of a high-strength combined buried pile retaining wall using data measured in the field. The experimental results showed that the cross-sectional force and displacement of the high-strength bonded pile retaining wall were reduced by 13.6~19.7%, the shear force increased by 0.7~4.7%, and the bending moment increased by 4.5~8.8% relative to the values for the C.I.P retaining wall. Examination of the amount of subsidence in the ground around the excavation showed that the maximum settlement of the C.I.P retaining wall was 46.89 mm and that at the high-strength combined buried pile retaining wall was 39.37 mm. Overall, designing a high-strength combined embedded pile retaining wall by applying the maximum bending moment and shear force calculated using the elastic beam method to the site ground was shown to achieve the safety of all members, as member forces were generated within the elastic region.

• Journal of Korean Society of Disaster and Security
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• v.15 no.3
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• pp.67-77
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• 2022

In South Korea, U-type girder development was attempted as a means to increase the length of I-type girder, but due to the large self-weight according to the post-tension method, the application of rail bridges of 30m or less is typical. There are not many examples of application of pre-tension type girder. This study does not limit the post-tension method, but applies the pre-tension method to induce a reduction in self-weight and materials used due to the reduction of the cross-section. In addition, we intend to apply the on-site pre-tensioning method using the internal reaction arm of the U-type girder. The prestressed concrete U-type girder bridge is composed of a concrete deck slab and a composite section. Compared to the PSC I-type, which is an open cross-section because the cross section is closed, structural performance such as resistance and rigidity is improved, the safety of construction is increased during the manufacturing and erection stage, and the height ratio is reduced due to the reduction of its own weight. Therefore, it is possible to secure the aesthetic scenery and economical of the bridge. As a result, it is expected that efficient construction will be possible with high-quality factory-manufactured members and cast-in-place members. In this paper, the introduction of the pre-tension method on-site and the analytical performance verification of the anchoring block for tension are included.

• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• Journal of Korean Philosophical Society
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• no.93
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• pp.175-199
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• 2011

The development of contemporary utilitarianism can be taken to be an aggregation of many attempts to surmount the limitations of classical utilitarianism. In these attempts, contemporary utilitarianism suggests alternatives to 'hedonism' and 'act-utilitarianism' which have been regarded as the common essential elements of classical utilitarianism. First, contemporary utilitarianism replaces the concept of 'happiness' or 'pleasure' in the classical utilitarianism with that of 'desire-fulfillment' or 'preference-satisfaction'. Through this replacement, contemporary utilitarianism tries to avoid the skeptical challenge to the mental state theory inherent in the classical concept of utility, and also to provide a more extensive conception of utility for a more satisfactory explanation of human welfare. Second, the development of rule-utilitarian theories which can evade the criticisms about 'counter-productivity' and 'counter-intuitiveness' of act-utilitarianism constitutes another important trend of contemporary utilitarianism. Characteristically, rule-utilitarian theories developed in the contemporary utilitarianism grope for some utilitarian system that can embrace socially accepted general norms. Lastly, contemporary utilitarianism responds to the criticisms related the problem of justice by reinterpreting the first principle of utilitarianism. This reinterpretation is an attempt to explain the egalitarian basis of utilitarianism through Bentham's dictum 'everyone counts for one, none for more than one'. It seems true that many influential criticisms in the latter half of 20th century cast a deep shadow on utilitarianism. But through the above attempt, contemporary utilitarianism proceeds to a better explanation of human welfare.

• 한국체육학회지인문사회과학편
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• v.51 no.3
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• pp.273-284
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• 2012

There is a large body of literature that studies serious leisure participants in a wide range of activities. By comparison, casual leisure has received scant attention, bearing few empirical studies. And serious leisure is often cast in an superior role in comparison with casual leisure for optimally healthy or beneficial leisure. The purpose of this study is to investigate the psychological functioning of 'casual leisure-serious leisure'. Especially, we pay more attention to reveal the positive functioning of casual leisure. It draws findings from the data of 291 university students. The results are as follows. First, in comparison with 'casual leisure group', 'serious leisure group' was showed a higher significant increase in leisure related functioning(leisure satisfaction and leisure benefits such as physical health, relationship and self-controlibility). However, There is no significant inter-group differences in 'self-life functioning variables(positive·negative self-esteem, happiness, quality of life)'. It implies even though serious leisure has more relation to positive leisure experiences, people maintain and enhance their self-esteem and experience satisfaction and happiness of their entire lives through casual leisure participation as much as serious leisure.

• Journal of the Daesoon Academy of Sciences
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• v.25_1
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• pp.1-22
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• 2015

This paper took Jeonkyeong (典經) of Daesunjinrihoe(大巡眞理會) as the basic text and studied how Kangjeungsan(姜甑山), the Sangje (上帝), had embraced Chinese myth in process of formation of his religious thought focusing on Yan Emperor(炎帝) Shennong(神農) myth and Shanrangang(禪讓) myth (namely Danchu myth). First when we examine the myth surrounding Kangjeungsan's birth, it deeply emraced a feeling-birth myth(感生神話), we could realize that this is a universe motif through myth of hero birth in East Asia. Further judging from the analysis of geographic space of Kangjeungsan's activity, it included a variety of mythical and Daoist related place names. I think this is because of the fact that birth place of Kangjeungsan and the surrounding area is the locality of Xian(仙) tradition where major characters of Danhak sect(丹學派) have been turned out, and that Korean way of Xian suppressed by the regulatory system has been widely rooted in the public. Especially it's interesting that Jeungsan, the pen name of Kangjeungsan, ambiguously connotes Siru mountain(甑山), a place of his training, and the spiritual realm of the 『Zhouyicantongqi(周易參同契)』. Then I examined the God of fire Shennong myth which has been actively admitted and embraced by Kangjeungsan. Kangjeungsan put the root of his pedigree on Shennong and there is a close affinity between Shennong and Dongyi(東夷) such as Buyeo(夫餘), Goguryeo(高句麗), etc. These Dongyi spirits are losers against the Chinese major myth and beings of ressentiment. At the same time the predecessor of Jiutianyingyuanleishengpuhuatianzun(九天應元雷聲普化天尊) who shares mythical characteristics with the God of fire Shennong was a formerly Taishi(太師) Wenzhong(聞仲) of Yin(殷) dynasty. He was defeated and died by Zhou(周) dynasty, and was deified. The fact that Kangjeungsan regarded himself as a descendent of Shennong and possessed divinity of Jiutianyingyuanleishengpuhuatianzun connotes that he represents all beings of ressentiment such as family of Yin and Dongyi. However, Kangjeungsan set a religious milestone by turning revenge for such ressentiment at tribe level into religious sublimation. At the end Shanrang myth which has been critically embraced by Kangjeungsan was reviewed. According to the existing Shanrang myth, Danchu(丹朱) was unworthy and not succeeded in the succession to the throne. Then good natured Emperor Shun(舜) succeeded to the throne from Emperor Yao(堯). However, the reality of Shanrang myth was a violent change of sovereign power and Danchu was a victim in the process of such violent change. Kangjeungsan shrewdly grasped the reality of ancient China and cast light on presence of Danchu. And he emphasized the need of religious sublimation of revenge, Haewon(解冤). His such awareness of culture had a close relation with revisionist standpoint of independent Danhak sect expressing a skeptical glance at systematic, commensurate and authentic historical view of Chinese civilization. And further Kangjeungsan cosmologically and causationally reinterpreted revenge of Danchu. He established a universal salvation theology which has a corresponsive connotation in regard to embracement of Shennong myth. In conclusion, embracement of Chinese myth by Kangjeungsan was a creative work of reinterpretation resulting in an inherent religious connotation through a process of appropriation, that is independent and selective introjection.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.2
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• pp.143-152
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• 2023

Although tooth wear is a normal process due to aging, severe tooth wear causes various complications such as increased tooth sensitivity, loss of tooth structure, and pulp complications. In the treatment of patients with excessive tooth wear, the evaluation of loss of vertical occlusal dimension should be prioritized. If it is necessary to increase the vertical dimension to secure the restoration space, it is important to establish a treatment plan with the comprehensive analysis and determine the minimum vertical dimension elevation. In this case, 66-year-old male patient with severe worn dentition wanted to restore masticatory function and improve esthetic restoration. In order to determine the appropriate vertical dimension of the patient, we evaluated oral examination, radiographic examination, and diagnostic cast examination, and performed rehabilitation with minimum vertical dimension elevation. As a result of observation for 8 months, the definitive prosthesis was completed with contact of all teeth in centric occlusion, and proper anterior/posterior guidance. Through the above process, satisfactory aesthetic and functional outcomes were obtained.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.89-99
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• 2006

The PCRW (Precast Concrete Retaining Wall) has many advantages compared with cast in place concrete retaining wall : shorter construction period, excellency of quality and minimum interference with the adjacent structure and traffics. However, shallow foundation type of PCRW, which has comparatively better ground condition, has some disadvantages such as difficulty in transportation and higher cost due to the size of PCRW being expanded by resisting only with self-weight if there is no other supplementary reinforcement. The presented study, in order to complement such disadvantages of PCRW, have applied the micropile method. The micropile method has advantages like low-cost and high-efficiency and does not require huge space, because it can be executed with small size equipment. However, the mechanical behavior characteristics of the PCRW reinforced by micropile, which is installed to improve the reinforcement effect, is not yet clearly identified and there is no suggested standard as to the length, diameter, install angle and install position of micropiles. Hence, this method is yet being designed depend on engineer's experience. In this study, various laboratory model tests as to sliding and overturning were performed in order to identify and present the optimum type of reinforcement and reinforcement effect of the PCRW reinforced by micropiles. In addition, it also executed numerical analysis for the purpose of verifying the optimum type of reinforcement for micropiles based on the results of laboratory model tests. The optimum reinforcement type of micropiles was estimated by model test and numerical analysis. The length of micropiles is 0.4 times wall height and the diameter is 0.04 times wall length.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.11-19
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• 2006

For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.9-20
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• 2023

Purpose: We investigated the effect of open tray impression using pick-up impression coping and close tray impression using transfer impression coping on the accuracy of impression in edentulous patients on their mandibular parts. the effect of material types of pick-up type impression copings for splinting in open tray impression on the accuracy of impression was also evaluated. Materials and Methods: Two implant fixtures were implanted in parallel in the left molar of the mandibular in the shape of a mandibular partial edentulous model. The 40 individual trays were fabricated using 3D printer. The prepared individual trays were classified into 4 groups (i.e., PN, PG, PH, and TN groups), and a total of 40 impression-takings were conducted. A master cast was connected to a Scan Body. The converted STL file was super-imposed on the scan images of the various groups. Results: The order of standard deviation values decreased as follows: PN (0.2343 ± 0.0844 mm), TN (0.2192 ± 0.0840 mm), indicating that the high accuracy of impression for TN group. In addition, for the comparison results between the material types used in splinting the open tray impression, the PH group showed a relatively lower standard deviation (0.1910 ± 0.1176 mm) than that of the PN group (0.2343 ± 0.0844 mm), PG group (0.2556 ± 0.1082 mm). Conclusion: The acrylic resin synthesized by light-induced polymerization exhibited a higher accuracy of impression taking than that of autopolymerizing acrylic resin. Meanwhile, the accuracy of impression taking was not dependent on the implant impression taking method or the presence of connection/fixation of impression copings.