• Journal of the Korean Geotechnical Society
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• v.37 no.3
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• pp.19-30
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• 2021

The presence of the hydrate-bearing sediments in Ulleung Basin of South Korea has been confirmed from previous studies. Researches on gas production methods from the hydrate-bearing sediments have been conducted worldwide. As production mechanism is a complex phenomenon in which thermal, hydraulic, and mechanical phenomena occur simultaneously, it is difficult to accurately conduct the productivity and stability analysis of hydrate bearing sediments through lab-scale experiments. Thus, the importance of numerical analysis in evaluating gas productivity and stability of hydrate-bearing sediments has been emphasized. In this study, the numerical parametric analysis was conducted to investigate the effects of the bottom hole pressure and the depressurization rate on the gas productivity and stability of hydrate-bearing sediments during the depressurization method. The numerical analysis results confirmed that as the bottom hole pressure decreases, the productivity increases and the stability of sediments deteriorates. Meanwhile, it was shown that the depressurization rate did not largely affect the productivity and stability of the hydrate-bearing sediments. In addition, sensitivity analysis for gas productivity and stability of the sediments were conducted according to the depressurization rate in order to establish a production strategy that prevents sand production during gas production. As a result of the analysis, it was confirmed that controlling the depressurization rate from a low value to a high value is effective in securing the stability. Moreover, during gas production, the subsidence of sediments occurred near the production well, and ground heave occurred at the bottom of the production well due to the pressure gradient. From these results, it was concluded that both the productivity and stability analyses should be conducted in order to determine the bottom hole pressure when producing gas using the depressurization method. Additionally, the stress analysis of the production well, which is induced by the vertical displacements of sediments, should be evaluated.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.250-273
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• 2020

The three-story stone pagodas in Hyeon-ri and Hwacheon-ri,Yeongyang Gyeongsangbuk-do are stone pagodas that exhibit the typical style of Unified Silla. The two pagodas are believed to have been built in the mid- and late 9th centuries at the latest, considering the style of the three-story roof stone on top of the double-tier base. This is also confirmed by the reliefs carved at the base and the first-story of the pagoda. The Four Heavenly Kings and the Twelve Zodiacal Animal Deities were first combined in the late 8th century in the stone pagoda at the Wonwonsa Temple Site, and the Eight Classes of Divine Beings was also the most popular carved pagoda reliefs in the 9th century. However, the two Yeongyang stone pagodas are characterized by a combination of the Four Heavenly Kings (1st story), the Eight Classes (top base), and the Twelve Zodiacal Animals (lower base), and the stone used for the pagoda consists of sedimentary rocks of the sandstone family, which comprise most of the geological strata in the Yeongyang area, rather than ordinary granite. The new combinations of the three types of guardian deities and the Eight Classes changed from seated to standing poses is interpreted as an attempt to enhance the Buddhist faith and cultural status of the Yeongyang area, along with the fact that the stone pagoda was built using local natural materials. The Eight Classes of the Yeongyang stone pagoda does not follow the two types of arrangement of the pagodas with the Eight Classes, but some of the deities have been relocated to a new location. Composed of AsuraGandharva on the east side, Naga-Mahoraga on the south, Deva-Garuda on the west, and Kimnara-Yaksa on the north, this form can be classified as a unique 'third layout of the Eight Classes' in the Yeongyang area. Such changes in the shape and posture of the reliefs reflect a new perception of the pagodas. The reason why the Gandharva and Yaksa statues were carved on the east and north sides, respectively, was because they were deemed subordinate to the Four Heavenly Kings, and the fact that the Naga and the Mahoraga were carved on the south side was presumed to have influenced the geographical location of the two pagodas on the northern side of Banbyeoncheon Stream. The Hyeon-ri and Hwacheon-ri three-story stone pagodas inherited the tradition of typical Unified Silla-period pagodas, while also bearing their own new regional characteristics.

• Korean Journal of Environment and Ecology
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• v.34 no.6
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• pp.515-529
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• 2020

Constructed wetlands undergo biological and physical changes such as an increase in the proportion of arid plants due to the natural succession process after formation. It can adversely affect not only the purification function but also the habitat of species. As such, this study aims to identify environmental factors affecting biodiversity and propose management plans based on the monitoring results of physical environmental changes and the emergence of species in seven constructed wetlands selected based on the water depth and surrounding conditions among the lands purchased by the Nakdong River basin. We examined the environmental conditions and emergence of the Odonata, which is a wetland-dependent species, to predict the trend of changes in biodiversity and abundance. The results showed that the open water area decreased as the emergent plants spread to the deep water in 2015 compared to 2012 when they were initially restored to a depth of 0.2 to 1 m. While a total of 54 dragonfly species were observed, the habitat diversity, such as vegetation, water surface, and grassland, remained similar to the initial formation of the wetlands despite the expansion of the emergent plants. On the other hand, the number of Agrionidae species, which prefer areas with fewer aquatic plants, decreased between 2012 and 2015 due to the diminished water surface. The p-values of the differences in the number of species and population between wetlands by year were 2.568e-09 and 1.162e-08, respectively, indicating the statistically significant differences. The decrease in open water surface was found to have the greatest effect on the biodiversity and habitat density of dragonflies. The time-series survey of constructed wetlands confirmed that the spread of Phragmites communis, P. japonica, Typha orientalis, etc., caused a decrease in species diversity. It suggests that environmental management to maintain the open water surface area is necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.599-609
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• 2021

A novel grounding system, which is presented in IEC 60364, has been adopted since 2021. A safety evaluation for the human body on the grounding system is required due to the various characteristics of the touch voltage and current passing when the human body experiences an electric shock. The Korea Electrical Safety Corporation (KESCO) and Korea Electric Association (KEA) have been conducting a safety technical education on the grounding system. On the other hand, it is difficult to instruct the electrical safety manager because of a lack of safety evaluations for the test equipment on the grounding system. Therefore, this paper modeled and implemented a test device for a safety evaluation depending on the grounding system of IEC 60364. Namely, this paper presents the modeling of the test device for a safety evaluation using PSCAD/EMTDC S/W, which is composed of an AC grid section, s test device section on the grounding system, and a sub-device section. This paper implemented a test device for safety evaluation, which consisted of an AC grid section, TT grounding system section, TN-S grounding system section, and monitoring section. From the simulation and test results with the safety characteristics of the human body in the TT and TN-S grounding system, when the fault impedances are 0[Ω], 10[Ω], and 100[Ω], the currents passing through the human body in the TT grounding system are 104[mA], 87.4[mA], and 35.5[mA], respectively. The corresponding currents in the TN-S grounding system are 54.9[mA], 4.1[mA], and 0.4[mA], respectively. Based on the results, the protection performance for an electric shock to the human body in the TN-S system is better than the TT system. This can be improved when the existing grounding system is changed from the TT system to the TN-S system.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.483-493
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• 2011

Erosion control dams play a primary role in preventing or controlling natural disasters (landslide and debris flow etc.) and also conserve ecosystem in forested watersheds. This study examines structural characteristics of the dams such as the height of ecosystem control and the ecosystem permeability of the erosion control dams under standard drawings and the existing construction works. The objective of this study was to characterize the type classification of erosion control dams as ecosystem. Average permeability was highest on eco-piller dam (63.0%), followed in increasing order by wire rope (13.9%), silt dam (10.9%), multifunctional dam (7.2%), and gravity dam (0.4%). The height of ecosystem control was highest on gravity dam (3.2 m), followed in increasing order by multifunctional dam (1.7 m), wire rope dam (1.2 m), silt dam (0.6 m), and eco-piller dam (0.0 m). Criteria for defining the height of ecosystem control was indefinite. We grouped erosion control dams into three functional types (eco-connection, eco-semi connection, and eco-disconnection) by considering physical and structural characteristics such as the ecosystem permeability and the height of ecosystem control. The type of eco-connection (permeability > 20%) had connection areas from streambed to adjacent riparian areas, and these connection areas serve as ecosystem corridors for fauna and flora. Typical wildlife species includes mammals, reptiles, amphibians, and fishes. The type of eco-semi connection (5% < permeability < 20%) had < 2 m in the eco-barrier height from streambed, however, this type of dams partially serve as wildlife corridors and often provide fish ways. The type of eco-disconnection (permeability < 5%) had > 2 m in the eco-barrier height from streambed, thereby preventing wildlife movement.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.432-440
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• 2011

The objective of this study was to investigate growth and fruiting characteristics (e.g., nut qualities) of chestnut (Castanea cerenata) after applying various fertilizer treatments at the cultivation site in Suncheon. Fertilizer treatments were designed as follow: liquid fertilizer, chemical fertilizer, organic fertilizer, and control. Both liquid and chemical fertilizer treatments provided the best growth in height and basal diameter. In addition, these two treatments were very effective for crown width of the trees between both east-west and north-south orientation. The liquid fertilizer treatment was effective on total length of the fruiting branch and length of the bearing to terminate part. Both liquid and chemical fertilizer treatments produced the longest length of basal to bearing part compared to the other two treatments. The liquid fertilizer treatment showed the most thickened basal diameter of the fruiting branch and the greatest diameter of above and below the bearing burr part. Elongation Index of the fruiting branch (EI) was the highest with liquid fertilizer treatment and the remaining four indices (Production Index of fruiting branch, PI; Ratio of Diameter between below and above bearing burr part, RD; Growth Index of fruiting branch diameter, GI; Thickness Index of fruiting branch or dormant branch, TI) were the highest with the chemical fertilizer treatment. Total number of produced branch per fruiting mother branch and number of small and weak branches per fruiting mother branch were highest on the control and liquid fertilizer treatment; however, all treatments produced similar numbers. The chemical and organic fertilizer treatments produced a high number of fruiting branches per fruiting mother branch, while organic and liquid fertilizer treatments produced a high number of burr per fruiting branch. The rate of commercializing on the basis of nut weight and quantity was higher on control (87.5%) than chemical fertilizer treatment (84.6%); however, the rate was even lower on liquid fertilizer treatment (84.3%) and organic fertilizer treatment (82.7%). The liquid fertilizer treatment showed the highest average of nut weight, while chemical fertilizer treatment showed the highest average number of fruiting burr. There was no significant difference in average number of normal nuts per burr among treatments. The yield per tree was high on chemical (8.2 kg) and liquid (8.0 kg) fertilizer treatments, but there was no significant difference among treatments. In the rate of nut grade on the basis of nut weight and quantity, the liquid fertilizer treatment, 43.5% and 34.3% more than large nut respectively, produced higher value chestnuts compared to other treatments.

• (The) Research of the performance art and culture
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• no.32
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• pp.171-208
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• 2016

Female folk song singers do not necessarily recognize the indigenous elements, which are, however, naturally reflected in the narration in the context. Singers of Taebaek Ararei recognize the dialect, the tone and the song when performing. Traditional Ararei had been performed by singers in the village of slash-and-burn field in Hwangji. Cheolam and Jangseong do not have their own traditional songs sing they are mining regions but had adopted songs from other areas including Gyeonggbuk, which still remain as alternative versions. Many elements of Jeongseon Arari and Samcheok Menari are in the narration and the songs. In terms of the context, alternative versions of Ararei are old Arirang melodies from slash-and-burn fields and were confirmed to be a very old form of oral folk songs in Gangwondo. Female singers of 3 generations, Hwaok Mun, Geumsu Kim and Hyojeong Kim, who keep the tradition and identity of Taebaek Ararei, show the integration of the past, present and future of Ararei. The Ararei Preservation Society continuously organizes singers' performances and maintains the tradition. The singer Hwaok Mun was born in Taecheon, Pyeongannamdo and moved to south at 5 and lived in Hajang, Samcheok and then moved to Jangseong and lived in Jaemungok. She is a mother of 6 children and has been a farmer for most of her life. She currently resides in Mungokdong and would sing Ararei at village feasts or events. She says she learned the song naturally because Ararei was sung very often in the past around Taebaek area. She is a typical native Arirang singer. The singer Geumsu Kim is a daughter of Hwaok Mun and leads the Taebaek Ararei Preservation Society to study, maintain and introduce the sound of Taebaek(Taebaek Arirang). She introduces Miner Arirang and Taebaek Ararei to the society members and the local residents. The singer Hyojeong Kim is a granddaughter of Hwaok Mun and follows the tradition of her grandmother and mother while adopting more modern Arirang contents.

• The Journal of Korean Philosophical History
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• no.43
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• pp.107-139
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• 2014

Tasan Chong Yak-yong has criticized Zhu Xi's metaphysical viewpoints of human being. Therefore he revealed his viewpoint of human being and the theory of moral practice through his thoughts about the Lord of Heaven and human nature with spiritual inclination toward goodness. He has drawn the Lord of Heaven into Confucianism again. Heaven as the Lord endows human being with a nature that enjoys virtues and detests vices. It watches human being's good and evil. Here we can say Heaven is a outer efficient cause of moral behavior. According to Tasan, human being has its own 'self directed weight'自主之權 so that he can make a judgment and decision about what to do. Therefore we have to do manifest this moral inclination which is a inner efficient cause of moral behavior. That is to say, we must follow the order of daoxin道心 inside our mind. If we did go against it, our mind would be uncomfortable. Now through the method of so-called shu恕 we need to put filial piety孝 fraternal respect弟 compassion慈 into practice. These three moral practices represent the spirit of reciprocity in Confucianism. These lead us to make an achievement of ren仁, representative virtue in the theory of moral practice. Our moral practice means the fulfillment of humanity. This is the way to serve Heaven. Tasan insists that theses are the core thoughts of Confucius and Mencius.

• The Southeast Asian review
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• v.28 no.1
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• pp.21-51
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• 2018

This article takes several approaches in explaining recent developments in Vietnam. First, it draws upon an array of sources that idealize Vietnam's embrace of capitalism and integration into the global market in order to sketch out its economy's progress in 2017. Second, it observes, evaluates, and diagnoses recent changes in the Vietnamese economy in the medium to long term by incorporating conflicting perspectives on Vietnam's performance as a capitalist country. Third, this article traces the power shifts that have risen from internal struggles in the Communist Party over political and social issues. Fourth, it elaborates on the aforementioned impact that foreign relations have had on socio-political developments in Vietnam, as well as the government's response. In so doing, it also attempts to evaluate, however briefly, the significance of the 25th anniversary of South Korea-Vietnam relations. Finally, it examines the public's reaction to the post-reform transitions in light of recent sociocultural changes. 2017 was a memorable year for Vietnam: a continuous march toward capitalism; the resulting expansion of the Vietnamese people's demands; political controversies and government control; the looming instability of United States-China relations and various attempts to address the situation. These events will inevitably replicate themselves in the future as the ostensibly socialist Vietnam adopts a capitalist model. The problem is that it is unclear whether these experiences will continue with the consent of the people of socialist Vietnam or engender resistance. It is difficult to achieve meaningful consent in the status quo of worsening inequalities, widespread corruption, monopoly on power, and sustained use of unskilled low-wage workers. In other words, when concerns such as welfare, public health, and the environment are set aside in favor of economic development and commercialization as they have been, discontent, rather than consent, will prevail. It is thus important to keep a watchful eye on the viability of the nominal economic growth, surface-level political stability, and strategic responses to foreign relations that took place in 2017.

• (The)Study of the Eastern Classic
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• no.70
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• pp.257-301
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• 2018

The purpose of the study is to examine righteous army activity and combat in Hapcheon during the Imjin invasion period. The resulting conclusions are as follows. First, Chung In-hong raised a righteous army in Hapcheon and Kim Myeon raised an army in Goryeong. Chung In-hong commanded the army and fought against Japanese army with a leadership of knowing the enemy and himself, and Kim Myeon commanded the army and fought against Japanese military with a leadership of harmony. Second, battles of Chung In-hong's righteous army are the first Mugye battle, the ambush battle in Sawon-dong, the Chogye Majin battle, the Aneon battle, and the third Seongju Castle battle. Battles of Kim Myeon's righteous army are the Yeongang battle, the Gaesanpo battle, the second Mugye battle, the Ucheok-hyeon battle, the Jirye battle, and the Sarangam battle. Battles that Chung In-hong and Kim Myeon united and fought are the first and second Seongju Castle battles. In Jeongyu Jaeran, Chung In-hong played a role of Jodosa who takes charge of provisions in the right area of Gyeongsang. In addition, Hapcheon was the access road and transport route where Japanese army entered Jeolla-do. Third, participation and role of Ming troops are part of restraint device against Japanese army with military tactics of ii chei(using foreigners to control foreigners) to remove Japanese army from Joseon and defend Yodong. After a victory of Li Rusong in Pyeongyang Castle in January, 1593(the 26th year of Seongjo), Ming troops pursued practical interest through peace talks rather than active battles. When there was practically Siege of Jinju, Yujeong troops of Ming entered with hand-to-hand martial arts of Sacheon soldiers in late June, 1593, but did not participate because they should wait for orders of Gyeongnyak Song Eung-chang and Admiral Li Rusong. Fourth, in the Imjin invasion period, Joseon suffered terrible damage such as ruin of the whole country by invasion of Japanese army and in need of aid of military rice from Ming troops, but righteous armies and the royal forces in each area cooperated so defeated Japanese army. It is understood through a case of Hapcheon in the right area of Gyeongsang. Especially, Joseon did not succumb to pressure of Ming troops that used full powers to two aspects such as settlement and battle with Japan during the war, and did not lose national confidence and pride by showing a fighting will to fight against Japanese army to the end with independence. Such a spiritual culture originated from homeland protection and loyalty to the king, and is national spirit of resistance that sublimates the united mind and spirit of community to protect a country against foreign invasion.