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Petrological Study on the Mantle Xenolith from Songaksan, Jeju Island (제주도 송악산에 분포하는 맨틀포획암의 암석학적 연구)

  • Youngwoo Kil
    • Korean Journal of Mineralogy and Petrology
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    • v.36 no.4
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    • pp.365-376
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    • 2023
  • Songaksan, formed about 3800 year ago, is one of the tuff rings in the Jeju Island. Mantle xenoliths, spinel peridotites, are enclosed in the Songaksan Trachybasalt. The spinel peridotites are less than 2 cm in size and are composed of olivine, orthopyroxene, clinopyroxene, and spinel. The uniform compositions of the minerals from core to rim indicate that equilibrium was reached in the spinel peridotites before these were enclosed in the host magma. The spinel peridotites originated at depths between 55 and 60 km with equilibrium temperatures ranging from 915 to 968℃. The spinel peridotites from Songaksan reveal porphyroclastic texture with a lot of neoblast minerals. Olivines display strong kink banding, indicating that the upper mantle of Songaksan has been deformed. The spinel peridotites from Songaksan have undergone about 5~7% fractional melting, and cryptic metasomatism by an silicate melt. The period of entrainment and transport of the spinel peridotites in the host magma is about 15 days.

Prediction of TBM disc cutter wear based on field parameters regression analysis

  • Lei She;Yan-long Li;Chao Wang;She-rong Zhang;Sun-wen He;Wen-jie Liu;Min Du;Shi-min Li
    • Geomechanics and Engineering
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    • v.35 no.6
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    • pp.647-663
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    • 2023
  • The investigation of the disc cutter wear prediction has an important guiding role in TBM equipment selection, project planning, and cost forecasting, especially when tunneling in a long-distance rock formations with high strength and high abrasivity. In this study, a comprehensive database of disc cutter wear data, geological properties, and tunneling parameters is obtained from a 1326 m excavated metro tunnel project in leptynite in Shenzhen, China. The failure forms and wear consumption of disc cutters on site are analyzed with emphasis. The results showed that 81% of disc cutters fail due to uniform wear, and other cutters are replaced owing to abnormal wear, especially flat wear of the cutter rings. In addition, it is found that there is a reasonable direct proportional relationship between the uniform wear rate (WR) and the installation radius (R), and the coefficient depends on geological characteristics and tunneling parameters. Thus, a preliminary prediction formula of the uniform wear rate, based on the installation radius of the cutterhead, was established. The correlation between some important geological properties (KV and UCS) along with some tunneling parameters (Fn and p) and wear rate was discussed using regression analysis methods, and several prediction models for uniform wear rate were developed. Compared with a single variable, the multivariable model shows better prediction ability, and 89% of WR can be accurately estimated. The prediction model has reliability and provides a practical tool for wear prediction of disc cutter under similar hard rock projects with similar geological conditions.

COMPARISON OF THE TIME-SIGNAL SYSTEM OF AUTOMATIC WATER CLOCKS DURING THE YUAN DYNASTY AND THE KING SEJONG ERA OF THE JOSEON DYNASTY (원대(元代)와 세종대(世宗代) 자동 물시계 시보시스템 비교)

  • YONG-HYUN YUN;SANG HYUK KIM;BYEONG-HEE MIHN;BYONG GUEN LEEM
    • Publications of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.1-12
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    • 2024
  • In this study, we investigated the time signal devices of Deungnu (circa 1270) and Gungnu (1354), the water clocks produced during the Yuan Dynasty (1271-1368). These clocks influenced Heumgyeonggaknu (1438) of the Joseon Dynasty (1392-1910), exemplifying the automatic water clocks of the Yuan Dynasty. Deungnu, Gungnu, and Heumgyeonggaknu can be considered as automatic mechanical clocks capable of performances. The Jega-Yeoksang-Jip (Collection of Calendrical and Astronomical Theories of Various Chinese Masters) contains records of Deungnu extracted from the History of the Yuan Dynasty. We interpreted these records and analyzed reproduction models and technical data previously produced in China. The time signal device of Deungnu featured a four-story structure, with the top floor displaying the four divine constellations, the third floor showcasing models of these divinities, the second floor holding 12-h jacks and a 100-Mark ring, and the first floor with four musicians and a 100-Mark Time-Signal Puppet providing a variety of visual attractions. We developed a 3D model of Deungnu, proposing two possible mechanical devices to ensure that the Time-Signal Puppet simultaneously pointed to the 100-Mark graduations in the east, west, south, and north windows: one model reduced the rotation ratio of the 100-Mark ring to 1/4, whereas the other model maintained the rotation ratio using four separate 100-Mark rings. The power system of Deungnu was influenced by Suunuisangdae (the water-driven astronomical clock tower) of the Northern Song Dynasty (960-1127); this method was also applied to Heumgyeonggaknu in the Joseon Dynasty. In conclusion, these automatic water clocks of East Asia from the 13th to 15th centuries symbolized creativity and excellence, representing scientific devices that were the epitome of clock-making technology in their times.

Brief Review on the Microbial Biodegradation of Asphaltenes (아스팔텐의 미생물 분해 연구동향)

  • Kyeongseok Oh;Jong-Beom Lee;Yu-Jin Kim;Joo-Il Park
    • Journal of the Korea Organic Resources Recycling Association
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    • v.32 no.2
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    • pp.27-35
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    • 2024
  • It was known that crude oil can be mainly divided into saturates, aromatics, resins, and asphaltenes. If microbial biodegradation of asphaltenes is effectively viable, additional oil production will be expected from depleted oil reservoir. Meanwhile, biodegradation can be applied to other aspects, such as the bioremediation of spilled oil. In this case, the biodegradation of asphaltenes also plays an important role. It has been already reported that asphaltenes are decomposed by bacterial consortia. However, the biodegradation mechanism of asphaltenes has not been clearly presented. The major reason is that the molecular structure of asphaltenes is complicated and is mainly in a aggregated form. In this paper, it was presumed that the biodegradation process of asphaltenes may follow the microbial oxidation mechanism of saturates and aromatics which are easier biodegradable than asphaltenes among the crude oil components. In other words, the biodegradation process was explained by serial stages; the contact between asphaltenes and bacteria in the presence of biosurfactants, and the decomposition of alkyl groups and fused-rings within the asphaltene structure.

Comparison of Hippological Differences Between Jeju Ponies and Jeju Pony Crossbreds : III. The Thickness of the Skin in Racepony Resources (제주마와 제주잡종마의 마학적 차이 : 3. 경주마 자원의 피부 두께)

  • Jeong Jin Yang;Yong Soo Park;Jae Hyuk Yang
    • Journal of Practical Agriculture & Fisheries Research
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    • v.25 no.4
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    • pp.39-43
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    • 2024
  • Little research has been done on investigating the specific characteristics of Jeju Ponies (Korean native horse) and Jeju Pony crossbreds. The authors performed evaluation of skin thickness of the skin of these breeds (n=205) at Jeju Race Park as a way of find of hippological difference. Results of this study showed that the Jeju Pony's skin were thicker than the Jeju Pony crossbred. The male's skin were thicker than the female's skin in two breeds respectively. Especially, in the Jeju Pony show significant differences (P < 0.05). In Jeju Pony crossbreds, as the skin thickness were thinner with age increase. 2-year-old group's skin significantly thinner than 3 and over 4-year-old groups. However, the Jeju Pony's skin were not significantly different by age. In conclusion, the authors thought that causes of the difference of the breeds were origin and genetic differences among the horse and the pony. Furthermore, the modified umbilical herniorrhaphy with rubber rings must be used cautiously in the Jeju Pony. It should be taken into account the animals' skin thickness when the leather goods created by using their skin.

Dimensional synthesis of an Inspection Robot for SG tube-sheet

  • Kuan Zhang;Jizhuang Fan;Tian Xu;Yubin Liu;Zhenming Xing;Biying Xu;Jie Zhao
    • Nuclear Engineering and Technology
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    • v.56 no.7
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    • pp.2718-2731
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    • 2024
  • To ensure the operational safety of nuclear power plants, we present a Quadruped Inspection Robot that can be used for many types of steam generators. Since the Inspection Robot relies on the Holding Modules to grip the tube-sheet, it can be regarded as a hybrid robot with variable configurations, switching between 4-RRR-RR, 3-RRR-RR, and two types of 2-RRR-RR, and the variable configurations bring a great challenge to dimensional synthesis. In this paper, the kinematic model of the Inspection Robot in multiple configurations is established, and the analytical solution is given. The workspace mapping is analyzed by the solution-space, and the workspace of multiple configurations is decomposed into the workspace of 2-RRR to reduce the analysis complexity, and the workspace calculation is simplified by using the envelope rings. The optimization problem of the manipulator is transformed into the calculation of the shortest contraction length of the swing leg. The switching performance of the Inspection Robot is evaluated by stride-length, turning-angle, and workspace overlap-ratio. The performance indexes are classified and transformed based on the proportions and variation trends of dimensional parameters to reduce the number of optimization objective functions, and Pareto optimal solutions are obtained using an intelligent optimization algorithm.

Determination of Si/Al Ratio of Faujasite-type Zeolite by Single-crystal X-ray Diffraction Technique. Single-crystal Structures of Fully Tl+- and Partially K+-exchanged Zeolites Y (FAU), |Tl71|[Si121Al71O384]-FAU and |K53Na18|[Si121Al71O384]-FAU

  • Seo, Sung-Man;Lee, Oh-Seuk;Kim, Hu-Sik;Bae, Dong-Han;Chun, Ik-Jo;Lim, Woo-Taik
    • Bulletin of the Korean Chemical Society
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    • v.28 no.10
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    • pp.1675-1682
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    • 2007
  • Large colorless single crystals of faujasite-type zeolite with diameters up to 200 μm have been synthesized from gels with the composition of 3.58SiO2:2.08NaAlO2:7.59NaOH:455H2O:5.06TEA:1.23TCl. Two of these, colorless octahedron about 200 μm in cross-section have been treated with aqueous 0.1 M TlC2H3O2 and KNO3 in order to prepare Tl+- and K+-exchanged faujasite-type zeolites, respectively, and then determined the Si/Al ratio of the zeolite framework. The crystal structures of |Tl71|[Si121Al71O384]-FAU and |K53Na18|[Si121Al71O384]-FAU per unit cell, a = 24.9463(2) and 24.9211(16) A, respectively, dehydrated at 673 K and 1 × 10-6 Torr, have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd m at 294 K. The two single-crystal structures were refined using all intensities to the final error indices (using only the 905 and 429 reflections for which Fo > 4σ(Fo)) R1/R2 = 0.059/0.153 and 0.066/0.290, respectively. In the structure of fully Tl+-exchanged faujasite-type zeolite, 71 Tl+ ions per unit cell are located at four different crystallographic sites. Twenty-nine Tl+ ions fill site I' in the sodalite cavities on 3-fold axes opposite double 6-rings (Tl-O = 2.631(12) A and O-Tl-O = 93.8(4)o). Another 31 Tl+ ions fill site II opposite single 6-rings in the supercage (Tl-O = 2.782(12) A and O-Tl-O = 87.9(4)o). About 3 Tl+ ions are found at site III in the supercage (Tl-O = 2.91(6) and 3.44(3) A), and the remaining 8 occupy another site III (Tl-O = 2.49(5) and 3.06(3) A). In the structure of partially K+-exchanged faujasite-type zeolite, 53 K+ ions per unit cell are found at five different crystallographic sites and 18 Na+ ions per unit cell are found at two different crystallographic sites. The 4 K+ ions are located at site I, the center of the hexagonal prism (K-O = 2.796(8) A and O-K-O = 89.0(3)o). The 10 K+ ions are found at site I' in the sodalite cavity (K-O = 2.570(19) A and O-KO = 99.4(9)o). Twenty-two K+ ions are found at site II in the supercage (K-O = 2.711(9) A and O-K-O = 94.7(3)o). The 5 K+ ions are found at site III deep in the supercage (K-O = 2.90(5) and 3.36(3) A), and 12 K+ ions are found at another site III' (K-O = 2.55(3) and 2.968(18) A). Twelve Na+ ions also lie at site I' (Na-O = 2.292(10) and O-Na-O = 117.5(5)o). The 6 Na+ ions are found at site II in the supercage (Na-O = 2.390(17) A and O-Na-O = 113.1(11)o). The Si/Al ratio of synthetic faujasite-type zeolite is 1.70 determined by the occupations of cations, 71, in two single-crystal structures.

"A Study on Hebrews Clothing in the Old Testament" - Especially on Hair Styles, Headgears, Footwear and Personal Ornaments - (구약성서(舊約聖書)에 나타난 히브리인의 복식(服飾) - 두식(頭飾), 신발 및 장신구(裝身具) 중심(中心)으로 -)

  • Park, Chan-Boo
    • Journal of the Korean Society of Costume
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    • v.10
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    • pp.63-80
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    • 1986
  • The Old Testament cotains mention of the history of creation and clothing in ancient Hebrew. This study dealt with Hebrew dress customs especially aimed at the manners of their hair styles, headgears, footwear and personal ornaments. References are Korean Revised Version, English King James Version and Revised Standard Version. There is little mention of hair styles and headgears in the Old Testament. Some sort of turban was worn by priests, and soldiers protected themselves with helmets, but most Israelitish men went bareheaded except on special occasions and often wear simple headbands. It was more common for women to use headwear of some type-turbans, scarves, and veils concealing the face. The veil was the distinctive female wearing apparel. All females, with the exception of maidservants and women in a low condition of life, wore a veil. It was the custom for women to wear a veil entirely covering their head in the public. Through most of the Old Testament periods long and thick hair was admired on men and women alike. The Hebrews were proud to have thick and abundant long hair, and they gave much attention to the care of their hair. The caring of hair was deeply related to their rituals. Nazirites never took a razor to their hair during his vow-days, but instead let it grow long, as an offering to God. Men would not cut their beards, but allow them to grow long. The Israelites' standard footwear was a pair of simple leather sandals. This was one of the items of clothing not highly prized. In a colloquial saying of the time, a pair of shoes signified something of small value, and to be barefoot except in times of mourning or on holy place, was a sign either of extreme poverty or humiliation, as in the case of war prisoners. Because precious stones were not mined in the Palestine-Syria region, Hebrews imported them from foreign country. They were consumer-to a large degree limited by their very modest standard of living-but not producers. Hebrews liked the precious stones and were motivated to acquire and wear jewels. Besides their use for adornment and as gifts, the precious or semiprecious stones were regarded by Jews of property. The Hebrews were not innovators in the field of decorative arts. The prohibition of the Law against making any "graven image" precluded the development of painting, sculpture, and other forms of representational art. Jewish men did not indulge in extravagances of dress, and there was little ornamentation among them. Men wore a signet ring on their right hand or sometimes suspended by a cord or chain around the neck. The necklaces, when worn by a male, also bore any symbol of his authority. Bracelets were extremely popular with both men and women, men usually preferring to wear them on their upper arms. The girdle was a very useful part of a man's clothing. It was used as a waist belt, or used to fasten a man's sword to his body, or served as a pouch in which to keep money and other things. Men often carried a cane or staff, which would be ornamented at the top. Among the women there was more apt to be ornamentation than among the men. Hebrew women liked to deck themselves with jewels, and ornamentation of the bride were specially luxurious and numerous. They wore rings on their fingers or On toes, ankle rings, earrings, nosering, necklace, bracelets. Their shapes were of cresent, waterdrops, scarab, insect, animal or plant. Sometimes those were used as amulets. They were made of ceramics, gold, silver, bronze, iron, and various precious stones which were mostly imported from Egypt and Sinai peninsular. Hebrews were given many religious regulations by Moses Law on their hair, headgears, sandals and ornamentation. Their clothing were deeply related with their customs especially with their religions and rituals. Hebrew religion was of monotheism and of revealed religion. Their religious leaders, the prophets who was inspired by God might need such many religious regulations to lead the idol oriented people to God through them.

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Chemo-Mechanical Analysis of Bifunctional Linear DGEBA/Linear Amine (DDM, DDS) Resin Casting Systems (DGEBA/방향족 아민(DDM, DDS) 경화제의 벤젠링 사이의 관능기 변화가 물성 변화에 미치는 영향에 대한 연구)

  • 명인호;정인재;이재락
    • Composites Research
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    • v.12 no.4
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    • pp.71-78
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    • 1999
  • To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with diaminodiphenyl methane (DDM), diaminodiphenyl sulphone (DDS) in a stoichiometrically equivalent ratio. From this work, the effect of aromatic amine curing agents. In contrast, the results show that the DGEBA/DDS cure system having the sulfone structure between the benzene rings had higher values in the conversion of epoxide, density, shrinkage (%), glass transition temperature, tensile modulus and strength, flexural modulus and strength than the DGEBA/DDM cure system having methylene structure between the benzene rings, whereas the DGEBA/DDM cure system presented higher values in the maximum exothermic temperature, thermal expansion coefficient, and thermal stability. These results are caused by the relative effects of sulfone group having strong electronegativity and methylene group having (+) repulsive property and stem from the effect of the conversion ratio of epoxide group. The result of fractography shows that the each grain size of the DDM/DGEBA system with feather-like structure is larger than that of the DDS/DGEBA system.

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Development of simple tools for algal bloom diagnosis in agricultural lakes (농업용 호소의 조류 발생 진단을 위한 간편 도구의 개발)

  • Nam, Gui-Sook;Lee, Seung-Heon;Jo, Hyun-Jung;Park, Joo-Hyun;Cho, Young-Cheol
    • Korean Journal of Environmental Biology
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    • v.37 no.3
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    • pp.433-445
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    • 2019
  • This study was designed to develop simple tools to easily and efficiently predict the occurrence of algal bloom in agricultural lakes. Physicochemical water quality parameters were examined to reflect the phytoplankton productivity in 182 samples collected from 15 agricultural lakes from April to October 2018. Total phytoplankton abundance was significantly correlated with chlorophyll-a (Chl-a) (r=0.666) and Secchi depth (SD) (r= -0.351). The abundances of cyanobacteria and harmful cyanobacteria were also correlated with Chl-a (r=0.664, r=0.353) and SD (r= -0.340, r= -0.338), respectively, but not with total nitrogen (TN) and total phosphorus (TP). The Chl-a concentration was correlated with SD (r= -0.434), showing a higher similarity than phytoplankton abundance. Therefore, Chl-a and SD were selected as diagnostic factors for algal bloom prediction, instead of analyzing the standing crop of harmful cyanobacteria used in algae alarm systems. Specifically, accurate diagnoses were made using realtime SD measurements. The algal bloom diagnostic tool is an inverse cone-shaped container with an algal bloom diagnosis chart that modified SD and turbidity measurement methods. Lake water was collected to observe the number of rings visible in the container or the number indicated in each ring, depending on the degree of algal bloom,and to determine the final stage of algal blooming by comparison to the colorimetric level on the diagnosis chart. For an accurate diagnosis, we presented 4-step diagnostic criteria based on the concentration of Chl-a and the number of rings and a fan-shaped algal bloom diagnosis chart with Hexa code names. This tool eliminated the variables and errors of previous methods and the results were easily interpreted. This study is expected to facilitate the diagnosis of algal bloom in agricultural lakes and the establishment of an efficient algal bloom management plan.