• Journal of the Korean Electrochemical Society
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• v.9 no.3
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• pp.124-131
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• 2006

For commercialization of molten carbonate fuel cell (MCFC), it has some problems to be overcome such as decrease of porosity and thickness of the anode under the operating condition (at $650^{\circ}C$ and working pressure of more than 2 $kg_f/cm^2$). Recently, Ni-Al alloy anode has been proposed to replace the conventional Ni-Cr anode as an alternative material to resist a creep and inhibit the sintering. The objective of this research is to sinter the green sheet of Ni-Al alloy anode during single cell pre-treatment process, which has several advantages like cost down and simplification of manufacturing process. However, the Ni-Al alloy anode prepared with a conventional pre-treatment process showed the phase separation of Ni-Al alloy and formation of micropore(${\leqq}0.4{\mu}m$), resulting in low creep resistance and high electrolyte re-distribution. In order to prevent the Ni-Al alloy anode from phase-separating, nitrogen gas was used in the process of pre-treatment. Introducing the nitrogen, the phase separation from Ni-Al alloy into nickel and alumina was minimized and increased creep resistance. However, there was some micropore formation on the surface of Ni-Al alloy anode during the cell operation due to creation of lithium aluminate. Addition of more amount of electrolyte into a cell, especially at cathode, made the cell performance stable for 2,000 hrs. Consequently, it was possible to make the Ni-Al alloy anode with good creep resistance by the modified in-situ sintering technique.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1381-1387
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• 1998

Laminated films were prepared by casting corn-zein and fatty acid mixed solutions onto ${\kappa}-carrageenan$ films, and the effect of various fatty acids with different concentrations on the film properties such as water vapor permeabilities (WVP), tensile strength (TS) and elongation was investigated. WVP of the film decreased as concentration of fatty acids increased, and the lowest WVP value $(0.497\;ng\;m/m^2\;s\;Pa)$ was achieved with laminated films containing 30% lauric acid/corn-zein. The TS of laminated edible film seemed to decrease as the concentration of fatty acids increased, and TS of the laminated film was the highest (36.21 MPa) when the film contained 10% oleic acid. Weight loss of the minced mackerels packaged with corn-zein/carrageenan film which did not contain fatty acid was 11.7%, but weight losses of the samples packaged with oleic acid and lauric acid were 6.97% and 0.81%, respectively, after 30 days storage at $-20^{\circ}C$. The laminated films had an effect on preventing oxidation of the minced mackerels during storage because of high oxygen barrier property of the film. All of the minced mackerels packaged with the laminated films greatly reduced the peroxide value (POV) compared with unpackaged minced mackerels during storage. Also, thiobarbituric acid (TBA) values of the minced mackerels packaged with the laminated films were lower than that of unpackaged minced mackerels during storage.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.395-402
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• 2011

The nanomechanical properties of fully lithiated and unlithiated silicon nanowire deposited on silicon substrate have been studied with atomic force microscopy. Silicon nanowires were synthesized using the vapor-liquid-solid process on stainless steel substrates using Au catalyst. Fully lithiated silicon nanowires were obtained by using the electrochemical method, followed by drop-casting on the silicon substrate. The roughness, derived from a line profile of the surface measured in contact mode atomic force microscopy, has a smaller value ($0.65{\pm}0.05$ nm) for lithiated silicon nanowire and a higher value ($1.72{\pm}0.16$ nm) for unlithiated silicon nanowire. Force spectroscopy was utilitzed to study the influence of lithiation on the tip-surface adhesion force. Lithiated silicon nanowire revealed a smaller value (~15 nN) than that of the Si nanowire substrate (~60 nN) by a factor of two, while the adhesion force of the silicon nanowire is similar to that of the silicon substrate. The elastic local spring constants obtained from the force-distance curve, also shows that the unlithiated silicon nanowire has a relatively smaller value (16.98 N/m) than lithiated silicon nanowire (66.30 N/m) due to the elastically soft amorphous structures. The frictional forces of lithiated and unlithiated silicon nanowire were obtained within the range of 0.5-4.0 Hz and 0.01-200 nN for velocity and load dependency, respectively. We explain the trend of adhesion and modulus in light of the materials properties of silicon and lithiated silicon. The results suggest a useful method for chemical identification of the lithiated region during the charging and discharging process.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.1-6
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• 2008

Purpose: Plastic optical monomer materials having ultra high refractive index have an income of the whole quantity from advanced nations to domestic companies which are related to plastic optical lens. It is necessary to develop novel plastic optical lens materials in order to overcome a FTA provision and revitalize a stagnating optical lens industry in the interior optical lens industries. The new plastic optical lens materials against the substitution effect of income should be gradually demanded. This work will be synthesized novel super high refractive monomer resin materials of urethane lens series and studied the properties of optical lens using it. Methods: ETS-4 (2-(2-mercaptoethylthio)-3-{2-[3-mercapto-2-(2-mercaptoethylthio)propyl thio]ethylthio}propane -1-thiol), which is optical lens monomer resin having super high refractive index, was synthesized and identified its structure and property by elemental analysis, EI-MS, TGA, FT-IR spectroscopy, $^1H$ and $^{13}C$ NMR spectroscopies. After mixing evenly from mixed monomer resin and diisocyanate series, it was casting in glass mold. After thermal curing, the obtained optical lenses were measured and compared with the refractive index and Abbe number for studies of their optical properties. Results: We have synthesized the novel ultra high refractive index monomer resin, ETS-4, and have identified its structure and property by elemental analysis, EI-MS, TGA, FT-IR spectroscopy, $^1H$ and $^{13}C$ NMR spectroscopies. The existence of three isomers for EST-4 was identified by $^{13}C$ NMR spectroscopy. The refractive index ($N_d$ at $25^{\circ}C$) of monomer resin in liquid state obtained from the Abbe refractometer was 1.647. The refractive indexes of raw plastic optical lenses prepared from the mixed ETS-4 monomer and diisocyanate series were in the range of 1.656~1.680. Conclusions: Novel super high refractive index plastic optical lens monomer was synthesized and analysed, the optical lenses prepared using it were colorless transparency and excellent properties. It is of utility for the industrialization.

• Korean Journal of Heritage: History & Science
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• v.50 no.1
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• pp.42-57
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• 2017

The Joseon Dynasty (1392~1910) had a long tradition of making official seals to commemorate the granting of official royal titles, including posthumous honorary titles, to its kings, queens, crown princes and queen dowagers. These royal seals were typically gold-plated or made of jade. After the death of its holder, each seal would be stored in the royal seal depository in the Royal Ancestral Shrine. Extensive efforts were made to restore the traditions and culture of the royal family of Joseon during the reign of King Sukjong (r. 1674~1720). In 1705, discussions were held about the royal ceremonial objects, including the royal seals, stored in the Royal Ancestral Shrine, resulting in the reproduction of a set of accessories related with the storage of royal seals and ten golden royal seals which had been lost during wars or had yet to be made. With these reproductions, each shrine chamber of the Royal Ancestral Shrine would have had at least one seal. The details of the reproduction project were meticulously recorded in The Royal Protocol by the Directorate for the Restoration of Golden Royal Seals("金寶改造都監儀軌"). Given that the restoration project was the single event that led to the reproduction of all the golden royal seals, it is reasonable to conclude that the directorate had fulfilled a historically significant function. In this study, the main discussion is focused on the establishment of the directorate and the storage and management of the damaged royal seals. The discussion includes the manufacturing process of the golden seals, for which The Royal Protocol is compared with other similar documents in order to gain more detailed knowledge of the measurements of the turtle knob, the lost-wax casting technique, the gold plating with mercury amalgamation technique, and other ornamentation techniques. The discussion also covers the activities of the artisans who made the royal seals, based on a study of the royal protocols; the styles of the artifacts, based on an examination of the remaining examples; and the techniques used by the Directorate for the Restoration of Golden Royal Seals to produce the royal seals in 1705.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.208-227
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• 2013

Twenty-seven bronze bowls excavated from the Goryo burial complex at Deobu-gol were examined for their microstructure and chemical composition to characterize the bronze technology practiced by commoners at the time. Results showed that the objects examined can be classified into four groups: 1) objects forged out of Cu-near 22%Sn alloys and then quenched; 2) objects cast from Cu-below 10% Sn alloys containing lead; 3) objects cast from Cu-10%~20% Sn alloys containing lead and then quenched; 4) objects forged out of Cu-10~20% Sn alloys containing lead and then quenched. This study revealed that the fabrication technique as determined by alloy compositions plays an important role in bronze technology. The use of lead was clearly associated with the selection of quenching temperatures, the character of inclusions and the color characteristics of bronze surfaces. It was found that the objects containing lead were quenched at temperatures of $520^{\circ}{\sim}586^{\circ}C$ while those without lead were quenched at the range of $586^{\circ}{\sim}799^{\circ}C$. The presence of selenium in impurity inclusions was detected only in alloys containing lead, suggesting that the raw materials, Cu and Sn, used in making the lead-free alloys for the first group were carefully selected from those smelted using ores without lead contamination. Furthermore, the addition of lead was found to have significant effects on the color characteristics of the surface of bronze alloys when they are subjected to corrosion during interment. In leaded alloys, corrosion turns the surface light green or dark green while in unleaded alloys, corrosion turns the surface dark brown or black. It was found that in fabrication, the wall thickness of the bronze bowls varies depending on the application of quenching; most of the quenched objects have walls 1mm thick or below while those without quenching have walls 1mm thick or above. Fabrication techniques in bronze making usually reflect social environments of a community. It is likely that in the late Goryo period, experiencing lack of skilled bronze workers, the increased demand for bronze was met in two ways; by the use of chief lead instead of expensive tin and by the use of casting suitable for mass production. The above results show that the Goryo bronze workers tried to overcome such a resource-limited environment through technological innovations as apparent in the use of varying fabrication techniques for different alloys. Recently, numerous bronze objects are excavated and available for investigation. This study shows that with the use of proper analytical techniques they can serve as a valuable source of information required for the characterization of the associated technology as well as the social environment leading to the establishment of such technology.

• 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.

• Clean Technology
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• v.28 no.1
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• pp.24-31
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• 2022

Petroleum-based plastics are used for various purposes and pose a significant threat to the earth's environment and ecosystem. Many efforts have been taken globally in different areas to find alternatives. As part of these efforts, this study manufactured alginate-based polyvinyl alcohol (PVA) blended films by casting from an aqueous solution prepared by mixing 10 wt% petroleum-based PVA with biodegradable, marine biomass-derived alginate. Glutaraldehyde was used as a cross-linking agent, and cardanol, an alkyl phenol-based bio-oil extracted from cashew nut shell, was added in the range of 0.1 to 2.0 wt% to grant antibacterial activity to the films. FTIR and TGA were performed to characterize the manufactured blended films, and the tensile strength, degree of swelling, and antibacterial activity were measured. Results obtained from the FTIR, TGA, and tensile strength test showed that alginate, the main component, was well distributed in the PVA by forming a matrix phase. The brittleness of alginate, a known weakness as a single component, and the low thermal durability of PVA were improved by cross-linking and hydrogen bonding of the functional groups between alginate and PVA. Addition of cardanol to the alginate-based PVA blend significantly improved the antibacterial activity against S. aureus and E. coli. The antibacterial performance was excellent with a death rate of 98% or higher for S. aureus and about 70% for E. coli at a contact time of 60 minutes. The optimal antibacterial activity of the alginate-PVA blended films was found with a cardanol content range between 0.1 to 0.5 wt%. These results show that cardanol-containing alginate-PVA blended films are suitable for use as various antibacterial materials, including as food packaging.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.343-358
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• 2011

As implant treatment has become popular, lots of different shapes and materials of the implant upper component have been supplied. And there are also diverse reports about failures including loosening of the abutment screw which is one of the most common reason. Purpose : The purpose of this study is to find out how different screw tightening orders and methods influence on screw loosening according to the different connection systems. The upper component was fabricated by casting method. After fabricating master models that are precisely attached to the upper component, 5 experimental models each for the external connection system and internal connection system were fabricated using splinting impression technique. First, to find out the influence of the screw tightening order, screws were tightened in 3 orders; 1-2-3-4, 2-3-1-4, 2-4-3-1. After tightening, removal torque values (RTV) of each group was measured. And also to find out the influence of screw tightening method, a model with 2-3-1-4 screw tightening order was tightened with 30 Ncm at one time(1-step method) and the RTV was compared with the same order group (2-3-1-4) in the 2 step method. In the external connection system, RTV appeared significantly lower in group 2-3-1-4 than group 2-4-3-1 (p<0.05). And also in the internal connection system, the RTV of group 2-3-1-4 appeared significantly lower than that of group 2-4-3-1 and 1-2-3-4 (p<0.05). When comparing the tightening number of the screw without considering the screw tightening order, the first tightened screw appeared significantly higher RTV than the second one in the external connection system (p<0.05), however there was no significant difference from the first tightened screw to the last tightened screw in the internal connection system. And there was no statistically significant difference between the two screw tightening methods in both internal and external connection system. In the comparison of external and internal connection system, each RTV appeared 16.27 Ncm and 14.25 Ncm and appeared as a statistically significant difference (p<0.05). There was a significant difference in RTV measured according to the screw tightening order. The lowest RTV appeared in the groups started tightening from the middle. There was also a significant difference in RTV between the two connection system groups. A further study is needed to find out the influence factors in RTV and also a study is required related to the load condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.737-747
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• 1999

To estimate biomass and distribution of the Antarctic krill (Euphausia superba), hydroacoustic survey was conducted on board of R/V Yuzhmorgeologiya, which was chartered by Korea Antarctic Research Program (KARP) group from 18 to 21 December 1998, in the northern part of the South Shetland Islands, Antarctic Ocean, The scientific echo sounder (towing body type) used was EK- 500 (SIMRAD, Norway) with echo integrator (BI-500) at 38 kHz frequency and recorded mean backscattering cross-section coefficient (SA) per 1 $mile^2$ of sea surface. Also, Bongo net sampling was carried out to determine the size of krill and CTD (Conductivity, Temperature and Depth) casting to understand physical structure. Water column was divided into 5 layers (22$\~$65 m, 65$\~$115 m, l15$\~$65 m, 165$\~$215 m and 215$\~$315 m) to know vertical distribution of krill biomass. The standard length of krill collected was between 30 mm and 51 mm, and adult krill had single mode (41 mm). Maximum horizontal length of krill patch was about 35 nautical mile and vertical thickness was about 275 m. High density of krill was appeared in frontal area between Circumpolar Deep Water (>$1^{\circ}C$) and very low temperature water mass (< $-0.5^{\circ}C$) that originate from Weddell Sea. According to the results calculated using target strength equation, krill density was totally higher in continental slope and open water areas than in coastal area. In the study area, krill seems to distribute in depth; density was low at first layer ($\={\rho}=17.0\;g/m^2$) and higher at fourth layer ($\={\rho}=40.19\;g/m^2$). The estimated krill biomass at total survey area and water column was about 2.77 million metric ion ($\={\rho}=151.0\;g/m^2$) and coefficient of valiance ( CV, $\%$) was 19.92. The proportions and biomass of krill biomass at each layer were as follows; layer 1 ($11.3\%$, 0.31 million metric ton, CV=16.24), layer 2 ($13.3\%$, 0.37 million metric ton, CV=34.91), layer 3 ($23.7\%$, 0.66 million metric ton, CV=41.5), layer 4 ($26.6\%$, 0.74 million metric ton, CV=27.84) and layer 5 ($25\%$, 0.69 million metric ton, CV= 26.83).