• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.4-23
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• 2021

The purpose of this study was to classify the types of tweezers used across time and to examine the social culture of periods through the use of tweezers. Chapter II summarized the terms for tweezers and looked at the use of tweezers in two cases related to the social culture and politics of a period. The first is the use of tweezers for beauty purposes. Men used tweezers as a kind of self-management to maintain their social status and power, and thus they helped develop a wide range of tweezers cultures. People with gray hair are usually old. The perception that we should step down from politics when we are aged has become strong. Therefore, politicians pulled out gray hairs with tweezers to maintain only black hair and show youth, which indicates that their social influence is still strong. The second is the use of tweezers for first aid. Chapter III classified tweezers by type during the Goryeo and Joseon periods. The tweezers are largely divided into basic and composite types. The basic type of tweezers is a form that has been continued since the Three Kingdoms Period and consists of tongs and handles, and a fixed type of tweezers with a fixed ring appeared. Composite tweezers are made by grafting earpick or multipurpose knives. Composite tweezers are all-in-one tweezers with an earpick and an all-in-one knife. Tweezers are usually all-in-one. Among the composite tweezers, rivet separation and ring separation are characterized by separation, unlike the all-in-one tweezers. The method of connecting is divided into rivets and connection rings. The all-in-one tweezers appear only during the Goryeo Dynasty and are characterized by the lifestyle that provides a glimpse of the tastes of contemporary users. The manufacturing takes shape after making a thin metal plate. Decorative techniques are carved on soft metal tweezers, such as silver and bronze with a line, point, and a pressed angle. These tweezers are presumed to have been used by the royal family or aristocrats. However, most tweezers are made of strong bronze or iron. Therefore, the majority of simple X-shaped patterns are sampled or without patterns. The biggest reason why there are such diverse types of tweezers is that the culture of tweezers was widespread regardless of the times. In addition, the basic type of tweezers has been used since the Three Kingdoms Period and has been modified and used together as necessary because the shape of tweezers is a practical daily tool. Study of metal crafts have been limited to royal objects and Buddhist crafts. We hope that research on everyday tools such as tweezers will continue to serve as an opportunity to examine the social and cultural aspects of the times in various ways.

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.456-463
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• 2004

To enhance the performance of anode-supported SOFC, single cell fabrication procedure was changed for better and resulting power generating characteristics of single cell were investigated. Liquid condensation process was employed for the granulation of NiO/YSZ powder mixture and the produced powder granules were compacted into anode green substrate by uni-axial pressing. YSZ electrolyte was printed on green substrate via screen-printing method and co-fired at 1400$^{\circ}C$ for 3 h. LSM/YSZ composite cathode of which the composition and heat treatment condition was adjusted to minimize the polarization#resistance with AC-impedance spectroscopy, was screen printed. The final single cell size from this multi-step procedure was 5${\times}$5 $\textrm{cm}^2$ and 10${\times}$10 $\textrm{cm}^2$. The maximum power densities of 5${\times}$5 and 10${\times}$10 single cells were about 0.45 W/$\textrm{cm}^2$ and 0.22 W/$\textrm{cm}^2$ at 800$^{\circ}C$, which are two times superior than those from single cells fabricated by the conventional process in previous our work.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1465-1471
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• 2007

Response surface methodology (RSM) was employed to optimize extraction conditions in order to find the maximal functional properties of fluid Cheonggukjang. Based on central composite design, a study plan was established with variations of microwave power, ethanol concentration, and extraction time. Regression analysis was applied to obtain a mathematical model. The maximum inhibitory of tyrosinase activity was found as 26.75% at the conditions of 30.56W microwave power, 2.40 g/mL of ratio of solvent to sample content and 10.00 min extraction time, respectively. The maximum superoxide dismutase (SOD)-like activity was 53.23% under the extraction conditions of 108.42 W, 4.38 g/mL and 7.84 min. Based on superimposition of three dimensional RSM with respect to extraction yield, inhibitory of tyrosinase activity and SOD-like activity obtained under the various extraction conditions, the optimum ranges of extraction conditions were found to be microwave power of $55{\sim}75$ W, ratio of solvent to sample content of $2{\sim}5$ g/mL and extraction time of $3.5{\sim}15$ min, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.464-469
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• 2015

Response surface methodology (RSM) was used to monitor extraction characteristics of extracts from Sarcodon aspratus. Based on a central composite design, independent variables were microwave power (30~150 W), ethanol concentration (0~100%), and extraction time (1~9 min). Dependent variables were yield, electron-donating ability, total phenol contents, and SOD-like activity. Coefficients of determination ($R^2$) for dependent variables ranged from 0.80 at 0.97. The maximum extraction yield was 50.28% under conditions of 125.1 W microwave power, 18.67% ethanolic concentration, and 7.06 min extraction time. The maximum extraction electron-donating ability was 22.14% under conditions of 31.09 W, 45.76%, and 4.32 min. The maximum extraction total polyphenol content was 30.54 mg tannic acid equivalent/g at 122.54 W, 48.05%, and 8.36 min. The maximum extraction SOD-like activity was 33.44% at 121.17 W, 47.42%, and 8.41 min. Based on superimposition of four dimensional RSM with respect to extraction yield, electron-donating ability, total polyphenol content, and SOD-like activity obtained under various extraction conditions, optimum ranges of extraction conditions were found to be microwave power of 78~88 W, ethanol concentration of 39~57%, and extraction time of 3.5~9 min.

• Composites Research
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• v.32 no.6
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• pp.301-306
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• 2019

Triboelectric nanogenerator (TENG) is one of the energy harvesting methods in spotlight that can convert mechanical energy into electricity. As TENGs produce high electrical output, previous studies have shown TENGs that can power small electronics independently. However, recent studies have reported limitations of TENG due to air breakdown and field emission. In this study, we developed a triboelectric nanogenerator that utilizes the metal-to-metal surface contact to induce ion-enhanced field emission and electron avalanche for electrons to flow directly between two electrodes. The average peak open-circuit voltage of this TENG was measured as 340 V, and average peak closed-circuit current was measured as 10 mA. The electrical output of this TENG has shown different value depending on the surface charge of surface charge generation layer. The TENG developed in this study have produced RMS power of 0.9 mW, which is 2.4 times higher compared to conventional TENGs. The TENG developed in this study can be utilized in charging batteries and capacitors to power portable electronics and sensors independently.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.1-6
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• 2014

The composite anodes of exfoliated graphite (EG) and multiwall carbon nanotube (MWCNT) were fabricated by using the binders with different content of epoxy in Nafion solution. The influence of the epoxy content in the anode binder on the performance of microbial fuel cell (MFC) was examined in a batch reactor. With the increase in the epoxy content in the anode binder, increase in physical binding force was observed, but at the same time an increase in the internal resistance of MFC was also observed. This was due to the increase in activation and ohmic resistance. For the anode binder without epoxy, the maximum power density was $1,892mW/m^2$, but a decrease in maximum power density was observed with the increase in the epoxy content in the anode binder. With the epoxy content of 50% in the anode binder, a decrease in the maximum power density to $1,425mW/m^2$ was observed, which about 75.3% of the anode binder without epoxy is. However, the material consisting of the same amount of epoxy and Nafion solution is a good alternative for anode binder in terms of durability and economics of MFC.

• Food Science and Preservation
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• v.14 no.5
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• pp.474-480
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• 2007

Response surface methodology (RSM) was employed to optimize extraction conditions preserving valuable functional properties of fluid Cheonggukjang obtained from red ginseng. Based on a central composite design, the study plan was established using variations in microwave power, ethanol concentration, and extraction time. Regression analysis was applied to obtain a mathematical model. A maximum electron donating ability (EDA) of 99.09% was obtained under the specific extraction conditions of microwave power 135.62 W, ratio of solvent to sample contents. 3.60 g/mL, and an extraction time of 11.79 min. The maximum inhibitory effect on tyrosinase activity was 10.02% at 119.16 W, 4.02 g/mL, and 5.57 min. The maximum superoxide dismutase (SOD)-like activity was 63.83% under the extraction conditions of 125.29 W, 4.04 g/mL, and 11.02 min. Based on superposition of four-dimensional RSM data obtained to optimize electron donating ability, nitrite-scavenging ability, inhibitory effect on tyrosinase activity, and SOD-like activity, the optimum ranges of extraction conditions were found to be a microwave power of $l{\sim}85 W$, a ratio of solvent to sample content of $1.4{\sim}2.8\;g/mL$, and an extraction time of $6.5{\sim}11\;min$.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.229-239
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• 2018

The purpose of this study was to effectively produce the biosugar from cell wall of lipid extracted microalgae (LEA) by using microwave-assisted pretreatment without enzymatic hydrolysis process. Response surface methodology (RSM) was applied to optimization of microwave-assisted pretreatment conditions for the production of biosugar based on enzyme-free process from LEA. Microwave power (198~702 W), extraction time (39~241 sec), and sulfuric acid (0~1.0 mol) were used as independent variables for central composite design (CCD) in order to predict optimum pretreatment conditions. It was noted that the pretreatment variables that affect the production of glucose (C6) and xylose (C5) significantly have been identified as the microwave power and extraction time. Additionally, the increase in microwave power and time had led to an increase in biosugar production. The superimposed contour plot for maximizing dependent variables showed the maximum C6 (hexose) and C5 (pentose) yields of 92.7 and 74.5% were estimated by the predicted model under pretreatment condition of 700 w, 185.7 sec, and 0.48 mol, and the yields of C6 and C5 were confirmed as 94.2 and 71.8% by experimental validation, respectively. This study showed that microwave-assisted pretreatment under low temperature below $100^{\circ}C$ with short pretreatment time was verified to be an effective enzyme free pretreatment process for the production of biosugar from LEA compared to conventional pretreatment methods.

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.159-164
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• 2016

The goal of this study is to implement a communication system that can monitor the status of the nacelle using the power cable itself, without the dedicated communication lines such as an UTP cable and optical fiber for the offshore wind turbine. An inductive coupling powerline communication system for a MW class offshore wind turbine was proposed and its communication performance was demonstrated. The inductive couplers was designed for operation at up to 500 A using a ferrite composite materials. Field test was carried out on the wind farms of Jeju island. Using the iperf communication test program, we have obtained more than 15 Mbps data transmission rate through the 100 m power cable that was installed between the nacelle and the bottom of the power converter. In the data transmission stability test for a week, there was no failure ever. The minimum transmission rate was 15 Mbps and the average data rate was about 20 Mbps. Next, we have installed an infrared camera inside the nacelle in order to measure the temperature distribution and variation of the nacelle. The real-time thermal image taken by the camera was successfully sent to the monitoring system without error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.297-305
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• 2019

This study was conducted to compare the factors affecting quality of life according to the perception of subjective body image in adult women as a secondary study of the 7th 1st year Korean National Health and Nutrition Examination Survey data. The subjects were 3,392 adult women and their general characteristics, physical factors and psychological factors were analyzed. Data were analyzed using the IBM SPSS 25.0 program after generating weighted composite sample plans and the significance level was set at 0.05. Factors influencing the quality of life of subjects who perceived their subjective body image as thin were education level, birth experience, depression, and subjective health and their explanatory power was 43.1%. Factors influencing the quality of life for those who perceived their bodies as moderate were education level, depression, and subjective health, and their explanatory power was 26.5%. Factors that affected quality of life for those who perceive their bodies as obese were age, weight change for one year, weight control for one year, presence of high blood pressure, BMI, and subjective health, and their explanatory power was 40.9%. The results of this study indicate it is necessary consider the factors influencing each subjective perception to improve individual quality of life.