• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.362-368
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• 2023

Multilayered actuators using Pb(Mg_1/3Nb_2/3)O₃-Pb(In_1/2Nb_1/2)O₃-PbTiO₃ (PMN-PIN-PT) crystals have demonstrated excellent properties, but are costly and lack mechanical strength. Textured PMN-PIN-PT ceramics exhibit robust mechanical strength and comparable properties to their single crystals form. However, the development of multilayered actuators using textured PMN-PIN-PT ceramics has not been achieved until now. This study presents the development of a multilayered actuator using textured 0.37PMN-0.29PIN-0.34PT ceramics with an Ag_0.9/Pd_0.1 inner electrode, co-fired at 950℃. A random 0.37PMN-0.29PIN-0.34PT ceramics multilayered actuator was also developed for comparison. The multilayered actuator consisted of 9 ceramic layers (36 ㎛ thickness) with an overall actuator thickness of 0.401 mm. The textured and random 0.37PMN-0.29PIN-0.34PT ceramics-based multilayered actuators achieved displacements of 0.61 ㎛ (0.15% strain) and 0.23 ㎛ (0.057% strain) at a low applied peak voltage of 100 V. These results suggest that the developed multilayered actuator using high-performance textured 0.37PMN-0.29PIN-0.34PT ceramics has the potential to replace expensive single crystal-based actuators cost-effectively.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.67-70
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• 2009

Printed electronics are emerging technology to realize various microelectronic devices via a cost-effective method. Here we introduce high performance inkjet printed polymer field-effect transistors and application to complementary integrated circuits with p-type and n-type conjugated polymers. The performance of devices highly depends on the selection of dielectrics, printing condition and device architecture. The device optimization and performances of various integrated circuits, e.g., complementary inverters and ring oscillators will be mainly discussed in this talk.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.45-51
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• 2009

A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

• 설비공학논문집
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• 제23권2호
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• pp.95-102
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• 2011

A ground loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. A proper design requires certain site specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U tube configurations on ground effective thermal conductivity and borehole thermal resistance. In this study, thermal response tests were conducted using a testing device to 9 different ground loop heat exchangers. From the experimental results, the length of ground loop heat exchanger affects to the effective thermal conductivity. The results of this experiment shows that higher thermal conductivity of grouting materials leads to the increase effective thermal conductivity from 22 to 32%. Also, mounting spacers have increased by 14%.

• 자원리싸이클링
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• 제30권4호
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• pp.20-26
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• 2021

태양전지용 실리콘은 주로 반도체급 실리콘 제조공정에서 발생하는 규격외 실리콘을 사용하여 왔다. 태양전지의 보급 활성화를 위해서는 보다 저렴한 정제 공정의 개발이 필요하다. 태양전지용 실리콘을 위한 저비용이면서 효율적인 방법은 금속급 실리콘을 정제하여 고순도화하는 것이다. 본 연구에서는 금속급 용융 실리콘 중의 Fe를 제거하기 위해 고주파 유도로 중에서 일방향 응고를 실시하였다. 실험조건과 실험결과를 유효 편석계수, Scheil 식 및 Peclet 수로 평가하였다. 시료의 하강속도가 감소함에 따라 불순물의 매크로 편석과 잉곳의 순도가 증가하였다. 이러한 결과는 시료의 하강속도 감소에 따른 유효 편석계수의 감소에 의한 것으로 생각된다.

• Corrosion Science and Technology
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• 제21권1호
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• pp.1-8
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• 2022

The use of cathodic protection for metals can be achieved by sacrificial anode CP or impressed current CP, or a combination of both. Cathodic protection is a highly effective anti-corrosion technique for submerged metals or metals in soil. But because the non-immersion atmospheric automobile environment is a high resistance environment, it is limited by fundamental cathodic protection. However, the application of cathodic protection to automobiles is attractive because of the possibility of maintaining corrosion resistance while using lower-cost materials. A commercially available product for automobiles that uses both sacrificial anode CP and impressed current CP was tested in a periodic salt spray environment to investigate the performance of the devices. Experimental results show that the metal to be protected has different anti-corrosion effects depending on the distance from the anode of the device, but it is effective for the entire 120 cm long specimen exposed with one anode. The cathodic protection is effective because the conductive tape attached to the anode of the structure to be protected acts as a constant electrolyte in wet and dry conditions. The results show that the entire standard passenger car can be protected by cathodic protection with 4 anodes.

• Membrane and Water Treatment
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• 제8권3호
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• pp.245-257
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• 2017

The separation of nicotine and tobacco-specific N-nitrosamines is a tough problem in tobacco industry. In this study, separation of nicotine from 4-(methylnitrosamino) -1-(3-pyridyl)-1-butanone (NNK) mixtures was investigated using electrodialysis by taking the principle of the protonation status difference between these two components. The results indicated that the solution pH has a dominant impact on the separation process. In a pH range of 5-7, nicotine molecules are existed as mono- and di-protonated ions and can be separated from the uncharged NNK molecules. The acidic electrolyte is conducive to the separation process from the point of flux and energy consumption; while the alkaline electrolyte has negative impact on the separation process. A current density of $10mA/cm^2$ is an appropriate value for the separation process. The lowest energy consumption of the separation process is 0.58 kWh/kg nicotine with the process cost to be estimated at only $0.208 /kg nicotine. Naturally, electrodialysis is a high-efficiency, cost-effective, and environmentally friendly process to separate and purify nicotine from tobacco juice.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.203-214
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• 2022

Thermoelectric (TE) heating and cooling devices, which are able to directly convert thermal energy into electrical energy and vice versa, are effective and have exhibited a potential for energy harvesting. With the increasing consumer demands for various wearable electronics, organic-based TE composite materials offer a promise for the TE devices applications. Conductive polymers are widely used as flexible TE materials replacing inorganic materials due to their flexibility, low thermal conductivity, mechanical flexibility, ease of processing, and low cost. In this review, we briefly introduce the latest research trends in the flexible TE technology and provide a comprehensive summary of specific conductive polymer-based TE material fabrication technologies. We also summarize the manufacture for high-efficiency TE composites through the complexation of a conductive polymer matrix/inorganic TE filler. We believe that this review will inspire further research to improve the TE performance of conductive polymers.

• 한국기계가공학회지
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• 제16권3호
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• pp.107-112
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• 2017

The purpose of this study was to develop an extractor to improve the effective ingredient of propolis. In order to improve the performance of conventional alcohol extraction at room temperature, a striking-type extractor used with a sprayed mist (alcohols, 95% alcohol) was developed for use at $40^{\circ}C$. Extraction of the effective ingredient of propolis was tested, and the resulting material was analyzed using a device. The extraction test of the mist spraying method indicated that the level of flavonoid was 1.56%, which is 1.5 times the 1.04% shown in existing data from a conventional stirred extractor. In addition, the extraction time can be reduced by half and the cost reduced by about 12.7% per year. It is confirmed that the extractor developed with a sprayed mist (alcohols, 95% alcohol) appears effective at the low temperature.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2533-2540
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• 2013

Background: Although screening is necessary where gastric cancer is particularly common in Asia, the performance outcomes of mass screening programs have remained unclear. This study was conducted to evaluate cost-effectiveness outcomes of the national cancer screening program (NCSP) for gastric cancer in South Korea. Materials and Methods: People aged 40 years or over during 2002-2003 (baseline) were the target population. Screening recipients and patients diagnosed with gastric cancers were identified using the NCSP and Korea Central Cancer Registry databases. Clinical outcomes were measured in terms of mortality and life-years saved (LYS) of gastric cancer patients during 7 years based on merged data from the Korean National Health Insurance Corporation and National Statistical Office. We considered direct, indirect, and productivity-loss costs associated with screening attendance. Incremental cost-effectiveness ratio (ICER) estimates were produced according to screening method, sex, and age group compared to non-screening. Results: The age-adjusted ICER for survival was 260,201,000-371,011,000 Korean Won (KW; 1USD=1,088 KW) for the upper-gastrointestinal (UGI) tract over non-screening. Endoscopy ICERs were lower (119,099,000-178,700,000 KW/survival) than UGI. To increase 1 life-year, additional costs of approximately 14,466,000-15,014,000 KW and 8,817,000-9,755,000 KW were required for UGI and endoscopy, respectively. Endoscopy was the most cost-effective strategy for males and females. With regard to sensitivity analyses varying based on the upper age limit, endoscopy NCSP was dominant for both males and females. For males, an upper limit of age 75 or 80 years could be considered. ICER estimates for LYS indicate that the gastric cancer screening program in Korea is cost-effective. Conclusion: Endoscopy should be recommended as a first-line method in Korea because it is beneficial among the Korean population.