• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.783-789
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• 2011

Recently, auto-thermal thermophilic aerobic digestion (ATAD) has a great attention for destruction of wasted sludge biomass in wastewater treatment plant. Reduction of sludge concentration has been successfully achieved with pilot scale ATAD and ceramic filtration process in field condition. However, high concentration of COD, total nitrogen (TN) and total phosphorus (TP) was observed in filtrate, which should be treated before recirculation of filtrate to biological wastewater treatment plant. This study was focused on removal of nitrogen and phosphorus contained in the filtrate of ATAD, using struvite crystallization method. The effect of operational and environmental parameters (such as, N, P and Mg ion concentration and molar ratio, pH, reaction time, agitation strength, seed dosage, and reaction temperature) on the treatment of TN and TP with struvite crystallization were evaluated. Magnesium (as $MgCl_26H_2O$) and phosphorus (as $K_2HPO_4$) ions were, if necessary, added to increase nitrogen removal efficiency by the crystal formation. Average concentration of $NH_4^+-N$ and $PO_4^{3-}-P$ of the filtrate were 1716.5 mg/L and 325.5 mg/L, respectively. Relationship between removal efficiencies of nitrogen and phosphorus and molar ratios of $Mg^{2+}$ and $PO_4^{3-}-P$ to $NH_4^+-N$ was examined. Crystal formation and nitrogen removal efficiencies were significantly increased as increasing molar ratios of magnesium and phosphorus to nitrogen. As molar ratio of $Mg^{2+}:PO_4^{3-}-P:NH_4^+-N$ were maintained to 2 : 1 : 1 and 2 : 2 : 1, removal efficiencies of nitrogen and phosphorus were 71.6% and 99.9%, and 93.8% and 98.6%, respectively. However, the effect of reaction time, mixing intensity, seed dose and temperature on the struvite crystallization reaction was not significant, comparing to those of molar ratios. Settled sludge volume after struvite crystallization was observed to be reduced with increase of seed dose and to be increased at high temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.55-61
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• 2003

This study was conducted to evaluate distribution and behavior characteristics of heavy metals for tidal flat sediments in the Saemankeum area. The value of heavy metal contents in the tidal flat sediments were higher than that surveyed in 1994, but showing that it's lower when compared with the value of Shiwha lake. Enrichment factors in the tidal flat sediments showed below 1 except for Pb and Zn. Metal excesses was appeared that Cu, Cr, Fe, Mn lacked and Pb, Zn were high. The correlation analysis between heavy metals and organic matters was found high positive relationship (r=0.424$\~$0.839), especially correlation coefficient between ignition loss and oxide Al, Fe, Mn showed high positive relationship above 0.7. The correlation analysis between Brain size and hear metals was found that as grain size was small, heavy metals contents were increased. Correlation coefficient between silt and heavy metals except for Cu, Pb showed high positive relationship as 0.552$\~$0.732.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.257-274
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• 2018

The purpose of this study was to evaluate the effect of acid-treatment conditions on the surface properties of the RBM (Resorbable Blast Media) treated titanium. Disk typed cp-titanium specimens were prepared and RBM treatments was performed with calcium phosphate ceramic powder. Acid solution was mixed using HCl, $H_2SO_4$ and deionized water with 4 different volume fraction. The RBM treated titanium was acid treated with different acid solutions at 3 different temperatures and for 3 different periods. After acid-treatments, samples were cleaned with 1 % Solujet solution for 30 min and deionized water for 30 min using ultrasonic cleanser, then dried in the electrical oven ($37^{\circ}C$). Weight of samples before and after acid-treatment were measured using electric balance. Surface roughness was estimated using a confocal laser scanning microscopy, crystal phase in the surface of sample was analyzed using X-ray diffractometer. Surface morphology and components were evaluated using Scanning Electron Microscope (SEM) with Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoemission Spectroscopy (XPS). Values of the weight changes and surface roughness were statistically analyzed using Tukey-multiple comparison test (p=0.05). Weight change after acid treatments were significantly increased with increasing the concentration of $H_2SO_4$ and temperature of acid-solution. Acid-treatment conditions (concentration of $H_2SO_4$, temperature and time) did not produce consistent effects on the surface roughness, it showed the scattered results. From XRD analysis, formation of titanium hydrides in the titanium surface were observed in all specimens treated with acid-solutions. From XPS analysis, thin titanium oxide layer in the acid-treated specimens could be evaluated. Acid solution with $90^{\circ}C$ showed the strong effect on the titanium surface, it should be treated with caution to avoid the over-etching process.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.192-211
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• 2021

In Seongju, Gyengsangbuk-do, the Placenta Chamber (胎室, Taesil) of 18 sons and a son of the crown prince of King Sejong(世宗大王) is located in one place. Taesil refers to the place where the umbilical cord and placenta, which are separated when the baby is born, are placed in a jar made of pottery and stone box and then buried on the ground. The placenta chamber in Seongju has the Buncheong ware (粉靑沙器) cover buried on the ground to protect the baby's placenta. These covers are all hemispherical, with a diameter of more the 20cm. The decorations were made using black and white inlaid techniques only on the outside. The Buncheong ware cover with this shape and pattern has been confirmed only in the placenta chamber in Seongju. This study targets 6 of the Buncheong ware cover whose owners were identified, when and where they were prepared, what the stylistic features and meanings are, and where it was produced. The results of the study are as follows. First, ss a result of reviewing the production background and procurement system of this bowl, it was inferred that it was sourced from Jangheunggo (長興庫) at the central government office, between 1436 and 1439, when the event to bury the placenta of royal members in the ground was the most active. Second, it analyzed the unique features of this cover, such as the shape, pattern, and baked traces. The shape and pattern were compared to the ritual objects contained in the Sejong Silok Oryeui (『世宗實錄』 「五禮」, Five Rites of King Sejong Chronicle) and the lid of the royal placenta jar made in the 15th and 16th centuries. Third, this study suggests that the baking method was based on the shape and location of the traces remaining outside the cover. Finally, the following data were used to estimate the production site: the relationship with the 'Jagiso (磁器所, ceramic workshop) registered in the Sejong Silok Jiriji (『世宗實錄』 「地理志」, Geographical Appendix of King Sejong Chronicle); various records of contribution and dedication about the Buncheong ware made here; and the Buncheong ware and related tools excavated from the kiln site in the area. The place where the Buncheong ware cover was produced is estimated to be the most likely production site for the kiln site in Chunghyo-dong Kiln Site, located in Jeolla-do province by synthesizing the data above.

• Korean Journal of Heritage: History & Science
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• v.41 no.2
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• pp.61-78
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• 2008

Celadons painted in underglaze iron brown 'Sung(成)' inscription are characteristic celadons excavated only at the No. 7 kiln site located at Sadang-ri(沙堂里), Daegu-myeon(大口面), Gangjin-gun(康津郡), Jeollanamdo(全羅南道), Korea and has inscription in the inner center of the foot by brush. The inscription was marked where it is not easily seen. it can be assumed that since it showed a variety of hand writings, many people were involved in manufacturing these celadons and the 'Sung' inscription was marked after workshop rather than manufacturer. It was also found that quality of glaze, paste, shape, pattern and firing method were same and these were manufactured with the same techniques in the same period. Kinds of these celadons were mainly sets of tablewares including bowl with handle, bowl, plate, cup, bowl with cover and bottle. Raised relief designs using extrusion technic were especially preferred rather than incised designs and inlaid designs. Cases of using inlaid designs were not frequently found compared to incised designs, thus it can be assumed that in this period, inlaid designs were not generally used. Special designs having the meaning of authority or dignity such as chrysanthemum, peony, parrot and lotus plate designs were not found. Foot was molded with 'U' type except some bowls with cover and plates and firing was done after glazing the whole surface of the ceramic with the support of quartzite at 3 to 4 places of inner bottom of foot. Production period of these celadons with 'Sung' inscription can not be confirmed from other excavation sites outside of No. 7 kiln site at Sadang-ri since there are no other excavation sites whose relics bear 'Sung' inscription. Through comparison research with other relics bear the characteristics of these celadons from tombs, temple sites, shipwrecks, production period of these celadons with 'Sung' inscription can be assumed as second quarter of 13th century. And since the quality of these celadons are generally inferior to the top-quality celadons which were supplied to royal familes and high-ranking aristocrats, it can be deducted that these celadons with 'Sung' inscription were supplied to classes lower than royal familes and high-ranking aristocrats. So it is considered that Celadons with 'Sung' inscription have a great significance as a chronological material to complement the blank of the first half of the 13th century because most of celadons with raised relief designs and engraved relief designs were attributed to 12th century, the period of prosperity.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.211-218
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• 2019

Purpose: The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness. Materials and methods: Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of $50{\mu}m$ were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (${\alpha}=.05$). Results: Mean marginal discrepancy was significantly smaller in the Group WM ($27.66{\pm}9.85{\mu}m$) and Group MS ($28.88{\pm}10.13{\mu}m$) than in the Group RP ($38.09{\pm}11.14{\mu}m$). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups. Conclusion: The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.112-129
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• 2019

This study investigates the influence and implications of the supervised process of production of flower vessels (花器) in 1411. The type, the production method, and the purpose of flower vessels (花器) were determined based on the workshops appearing in King Sejong-Sillok, Chiriji ("世宗實錄" "地理志") and Gyeongsang-do Chiriji ("慶尙道地理志"), considering articles excavated from Sangju kiln sites. In addition, the implications and the starting point of production of flower vessels (花器) in the Joseon Dynasty were identified. During the Joseon Dynasty, an effort was made to reorganize the government offices, to align ritual systems in the early 15th century. Preparation for rituals, preparation of supplemental utensils used in ancestral rites (祭器), the construction of architecture related to the Royal Family, and the production of weaponry (武器) were supervised. In 1411, flower vessels (花器) had a preferred supervised process of production as well, which means being recognized as a subject of maintenance for the Joseon Dynasty's aims. Flower vessels (花器) had been produced using grayish-blue powdered celadon (粉靑沙器) as flower pots (花盆), and as celadon flower pot-support (花臺), at Sangju kiln sites in particular, since 1411. Interestingly, products had been manufactured in royal kilns as well as in a few other kilns similar to the supervised process of production of flower vessels (花器) in the middle of the 15th century. It means that this effected the Gyeon-yang (見樣) supervised process of flower vessel (花器) production in 1411. At that time, the Joseon Dynasty used Gyeon-yang (見樣) for imperial gifts for the Ming Dynasty and on separate manufactured articles to ensure the standards of production. Gyeon-yang (見樣) affected the production of ceramic utensils used in ancestral rites (祭器), and government officials in Saongwon (司饔院) supervised the production of ceramics for the Royal Family year after year. In sum, it was flower vessels (花器) using Gyeon-yang (見樣) that provided precise production rules to supervise the process of production in 1411.

• Korean Journal of Heritage: History & Science
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• v.34
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• pp.124-136
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• 2001

Among many different types of wares, we have amazing Sacred Water-pot(따르개, 注子) from Goryo-period(고리, 高麗, 918-1392). The stylistic peculiarity of Jung-Byoung(정병, 淨甁) is described in "Goryo-Dhogyoung, 고리도경, 高麗圖經", the classical design canon. It is said, "A sharpened mouth with narrow and prolonged neck is attached upon the broad mouth with thicker and even longer neck of the pot whose body intimates to the shape of melon." One could find this Jung-Byoung similar to the Indian drinking water jar, Kundika, which has been. even today, an everyday article in houses as well as in temples. In the early Buddhist cult, the object had been adopted as personal belonging of the Bodhisattvas(보살, 菩薩), especially of the Bodhisattva Avalokitesvara(관세음보살,觀世音菩薩). In short, the purifying character of water is met by the sacred ware to deliver the refreshing Sweet-Water(Holy-Water, 깨맑물, 단물, 단이슬물, 정수, 감로, 감로수, 성수, 淨水, 甘露, 甘露水, 聖水): For the holy purpose of fulfilling the thirst of people, of symbolozing the virtuous dharma. Thus, Ggamslkh-Byoung(깨맑병,淨水), the literal Korean name, denotes purifying and clarifying and clarifying water-pot to us. Among many other Asian countries, India, China, Korea, and Japan have a profound cult of the sacred water-pot(Ggamalkh-Byoung, Jung-Byoung, 깨맑병, 정병, 정수병, 감로병, 감로수병, 淨甁, 淨水甁, 甘露甁, 甘露水甁). Therefore, this charming holy object drew much attention not only from master artisans to shape and deliver them to people but also from painters and sculptors for their endowment of the sacred images dedicated to Buddha(부처,佛,佛陀). In China, the sacred water pot emerged in the period of Tang(당, 唐, 618~907)-Period and underwent much sophistication later on, I. e., from earthenware, ceramic-porcelain, bronze, and silver. However, the following represents a challenge to the well-known Goryo-Thangka(고리불화, 高麗佛畵) Painting of Bodhisattva Avalokitesvara to our speculation on the Sacred Water-pot(정병, 淨甁). The image suggests, when examined closely, that the Sacred Water-pot has been accompanied by, or placed in, a transparent glasswere(유리그릇) or crystalbowl(수정그릇)! We have no other physical proof of the existence of such a Holding-Bowl(받침그릇, 承盤), except for in this particular painting. This Holding-Bowl would have not been a mere elaboration on the practicality of controling the drips from the mouth of the pot. As in the chapter on Tang-ho(탕호, 湯壺), or thermal bowl, in the "Goryo-Dhogyoung" it advises readers that this style of bowl is to be filled with hot water, and thus function as a preserver of heat in the water inside the pot. As an offering to the Buddha, the Sacred Water-pot could have been used for serving him hot tea. Hence the sacred bottle is to contain the refreshing water, the water transcends to nectar, and the nectar is prepared as a nectar tea to offer the Buddha. For both the Holding-Bowl of Ggamalkh-Byoung(Jung-Byoung)and the Celestial-Robe(날개옷, 天衣) of the Bodhisattva Avalokitesvara, whose specified character is the Water-Moon(수월, 水月) in this particular Thangka(불화, 佛畵) painting, the transparency is essential. This is to refer to the purity and the lucid clarity of Bodhisattva Avalokitesvara and at a deeper level, to refer to the world of Buddhas-the Tushita(Paradise, Heaven, Eden, 극락, 불세계, 極樂, 佛世界). Howerver, without the discovery of an actual Holding-Bowl, accompanied by a Sacred Water-pot, such speculation will necessarily remain hypothetical. Nevertheless, there is an abundance of evidence of our ancient craftsmanship in jade and ctystal, dating back to the Bronze Age(1000~2B.C.) in Korea. By the time of the Three Kingdom-Period(삼국시대, 三國時代, 57B.C.~935A.D.), and especially the Silla(신라, 新羅, 57B.C.~935A.D.)-Empire, the jade and crystal ornamentation had become very intricate indeed. By the Goryo-Period(918~1392) and Chosun-Period(조선, 朝鮮,1392~1910),crystal-ware and jade art were popular in houses and Buddhist temples, whose master artsanship was heightened in the numerous Sarira-Cases(사리그릇, 舍利器), containing relics and placed inside Stupas(탑, 투, 搭)! Therefore, discovering a tiny part of the crystal or jade Holding-Bowl for the Sacred Water-pot and casting full light on this subject, would not be totally impossible. Lastly the present article shares the tiny hope for a sudden emergence of such a Holding-Bowl.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.81-88
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• 2021

In this paper, by applying LTCC substrate, the library of the passive elements is implemented. And it can be used in 24 GHz circuits. Depending on how to use it to the circuit, it is required large value by designing the basic structures such as electrode capacitor and spiral inductor. However they are not available in high-frequency domain, because their SRF(Self-Resonant Frequency) is lower than the frequency of 24-GHz. By solving the limit, this paper devised passive elements classified for the DC and the high-frequency domain. The basic structure is suitable for low frequency under 1~2 GHz like DC. The microstrip λ/8 length stub structure is proposed to use for high-frequency like 24-GHz. The open and short stub structure operate as a capacitor and inductor respectively, also they have their impedances. Through their impedances, we can extract the value with the impedance-related equation. In this paper, the proposed passive elements are produced with the permittivity 7.5 LTCC substrate, the basic structure which are available in the DC constituted a library of capacitance of 2.35 to 30.44 pF and inductance of 0.75 to 5.45 nH, measured respectively. The stub structure available in the high-frequency domain were built libraries of capacitance of 0.44 to 2.89 pF and inductance of 0.71 to 1.56 nH, calculated respectively. The measurements have proven how to diversify value, so libraries can be built more variously. It will be an alternative to the passive elements that it is possible to integrate with the operation circuit of radar module for the frequency 24-GHz.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.83-89
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• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.