• 공업화학
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• 제30권2호
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• pp.186-189
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• 2019

폴리피롤(polypyrrole)은 전기를 전도하는 고분자로 뛰어난 전기적 신호 전달을 지니며, 사이클로덱스트린(cyclodextrin)은 환형다당류(cyclic oligosaccharide) 분자들로서 저분자량 물질을 포획할 수 있는 친환경 물질로 널리 활용되고 있다. 따라서 이들 두 가지 물질을 혼합하여 혼성체를 제조할 수 있다면 사이클로덱스트린이 host가 되어 guest 물질을 포획하였을 때 발생하는 전기 신호를 폴리피롤이 민감하게 전달할 수 있게 되어 우수한 감지 능력을 갖게 된다. 따라서 본 연구에서는 폴리피롤/사이클로덱스트린 혼성체를 간단한 수용액 방식으로 제조하여, 제조된 혼성체를 하이드로젤(hydrogel)에 도입하여 건조한 후 금 전극 위에 적용하여 대표적인 유해성 분자인 메틸파라벤(methyl paraben)을 검출할 수 있는지에 대해서 살펴보았다. 그리고 폴리피롤만으로 이루어진 물질과 비교해 봤을 때, 사이클로덱스트린의 도입효과는 존재하는 것으로 나타났다. 이 연구는 전도성 고분자와 친환경 분자 혼성체를 유해물질 감지에 활용할 수 있는 가능성을 제시하고 있다.

• 농업과학연구
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• 제47권4호
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• pp.753-767
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• 2020

The commercial value of strawberries is affected by various factors such as their shape, size and color. Among them, size determined by weight is one of the main factors determining the quality grade of strawberries. In this study, image technology was developed to predict the weight of strawberries using the shape characteristics of strawberry cultivars. For realtime weight measurements of strawberries in transport, an image measurement system was developed for weight prediction with a charge coupled device (CCD) color camera and a conveyor belt. A strawberry weight prediction algorithm was developed for three cultivars, Maehyang, Sulhyang, and Ssanta, using the number of pixels in the pulp portion that measured the strawberry weight. The discrimination accuracy (R2) of the weight prediction models of the Maeyang, Sulhyang and Santa cultivars was 0.9531, 0.951 and 0.9432, respectively. The discriminative accuracy (R2) and measurement error (RMSE) of the integrated weight prediction model of the three cultivars were 0.958 and 1.454 g, respectively. These results show that the 2D imaging technology considering the shape characteristics of strawberries has the potential to predict the weight of strawberries.

• 대한금속재료학회지
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• 제56권12호
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• pp.900-909
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• 2018

A $ZnO/TiO_2$ photocatalyst decorated with PbS quantum dots (QDs) was synthesized to achieve high photocatalytic efficiency for the decomposition of dye in aqueous media. A $TiO_2$ porous layer, as a precursor photocatalyst, was fabricated using micro-arc oxidation, and exhibited irregular porous cells with anatase and rutile crystalline structures. Then, a ZnO-deposited $TiO_2$ catalyst was fabricated using a zinc acetate solution, and PbS QDs were uniformly deposited on the surface of the $ZnO/TiO_2$ photocatalyst using the successive ionic layer adsorption and reaction (SILAR) technique. For the PbS $QDs/ZnO/TiO_2$ photocatalyst, ZnO and PbS nanoparticles are uniformly precipitated on the $TiO_2$ surface. However, the diameters of the PbS particles were very fine, and their shape and distribution were relatively more homogeneous compared to the ZnO particles on the $TiO_2$ surface. The PbS QDs on the $TiO_2$ surface can induce changes in band gap energy due to the quantum confinement effect. The effective band gap of the PbS QDs was calculated to be 1.43 eV. To evaluate their photocatalytic properties, Aniline blue decomposition tests were performed. The presence of ZnO and PbS nanoparticles on the $TiO_2$ catalysts enhanced photoactivity by improving the absorption of visible light. The PbS $QDs/ZnO/TiO_2$ heterojunction photocatalyst showed a higher Aniline blue decomposition rate and photocatalytic activity, due to the quantum size effect of the PbS nanoparticles, and the more efficient transport of charge carriers.

• 한국인터넷방송통신학회논문지
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• 제21권1호
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• pp.175-179
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• 2021

최근 1인 가구 비율의 증가로 합리적인 개인 이동수단에 대한 수요가 증가하면서 간편하고, 간결하게 이용할 수 있는 'Personal Mobility'산업이 급성장하였다. 실제로 한국교통연구원의 자료에 따르면 2022년에는 전동킥보드의 수가 20만대로 확대될 것으로 전망되었다. 전기를 동력으로 작동되는 전동킥보드의 특성상 안정적이고, 효율적인 배터리 수급이 가장 기본적이면서도 중요한 이슈가 된다. 최근 전동킥보드를 이용한 사용자의 후기에 따르면 전동킥보드를 이용하려고 하였으나 배터리가 방전상태이거나 배터리 충전 정도가 낮아 이용을 하지 못하는 경우가 종종 발생되고 있는 것을 확인할 수 있다. 이에 본 논문은 전동킥보드의 안정적인 배터리 사용을 위한 태양광 충전시스템을 제안한다. 본 시스템이 적용 될 경우 전동킥보드의 친환경적인 충전 방법이 될 뿐만 아니라 주행 중에도 안정적으로 배터리 수급이 가능할 것으로 예상된다.

• 한국군사과학기술학회지
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• 제24권2호
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• pp.211-218
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• 2021

This paper deals with the computational work to characterize the formation and pinching of a plasma in an X-pinch configuration. A resistive magnetohydrodynamic model of a single fluid and two temperature is adopted assuming a hollow conical structure in the (r,z) domain. The model includes the thermodynamic parameter of tungsten from the corrected Thomas-Fermi EOS(equation of state), determining the average ionization charge, pressure, and internal energy. The transport coefficients, resistivity and thermal conductivity, are obtained by the corrected Lee & More model and a simple radiation loss rate by recombination process is considered in the simulation. The simulation demonstrated the formation of a core-corona plasma and intense compression process near the central region which agrees with the experimental observation in the X-pinch device at Seoul National University. In addition, it confirmed the increase in radiation loss rate with the density and temperature of the core plasma.

• Current Photovoltaic Research
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• 제9권4호
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• pp.145-159
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• 2021

Light soaking (LS) stability in polymer solar cells (PSCs) has always been a challenge to achieve due to unstable photoactive layer-electrode interface. Especially, the electron transport layer (ETL) and photoactive layer interface limits the LS stability of PSCs. Herein, we have modified the most commonly used and robust zinc oxide (ZnO) ETL-interface using an organic dye molecule and a co-adsorbent. Power conversion efficiencies have been slightly improved but when these PSCs were subjected to long term LS stability chamber, equipped with heat and humidity (45℃ and 85% relative humidity), an outstanding stability in the case of ZnO/dye+co-adsorbent ETL containing devices have been achieved. The enhanced LS stability occurred due to the suppressed interfacial defects and robust contact between the ZnO and photoactive layer. Current density as well as fill factors have been retained after LS with the modified ETL as compared to un-modified ETL, owing to their higher charge collection efficiencies which originated from higher electron mobilities. Moreover, the existence of less traps (as observed from light intensity-open circuit voltage measurements and dark currents at -2V) are also found to be one of the reasons for enhanced LS stability in the current study. We conclude that the mitigation ETL-surface traps using an organic dye with a co-adsorbent is an effective and robust approach to enhance the LS stability in PSCs.

• 한국표면공학회지
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• 제56권1호
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• pp.104-114
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• 2023

Three dimensional (3D) porous structures consisting of Cu@CoO core-shell-type nano-dendrites were synthesized and tested as the anode materials in lithium secondary batteries. For this purpose, first, the 3D porous films comprising Cu@Co core-shell-type nano-dendrites with various thicknesses were fabricated through the electrochemical co-deposition of Cu and Co. Then the Co shells were selectively anodized to form Co hydroxides, which was finally dehydrated to get Cu@CoO nanodendrites. The resulting electrodes exhibited very high reversible specific capacity almost 1.4~2.4 times the theoretical capacity of commercial graphite, and excellent capacity retention (~90%@50^th cycle) as compared with those of the existing transition metal oxides. From the analysis of the cumulative irreversible capacity and morphology change during charge/discharge cycling, it proved that the excellent capacity retention was attributed to the unique structural feature of our core-shell structure where only the thin CoO shell participates in the lithium storage. In addition, our electrodes showed a superb rate performance (70.5%@10.8 C-rate), most likely due to the open porous structure of 3D films, large surface area thanks to the dendritic structure, and fast electron transport through Cu core network.

• Korean Chemical Engineering Research
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• 제61권1호
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• pp.155-161
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• 2023

이온 농도 분극 현상은 전기투석, 전기화학 전지에서 일어나는 기초 이동 현상일 뿐만 아니라, 생체 물질 전처리용 농축 장치의 핵심 기작으로 활용된다. 외부 인가 전압에 의해 발생한 이온 농도 분극 현상은 분석 물질의 농축에 필요한 국소적으로 증폭된 전기장을 통해 물질의 농축을 가능케 한다. 그러나 기존의 농축 기작은 농축의 평형 지점이 불분명하며, 농축 플러그의 유체역학적 불안정성의 두가지 문제점을 가지고 있다. 본 연구에서는, 이온 농도 분극 기반의 농축 기작의 한계점을 해결하기 위해 막다른 미세유로와 양이온 교환막을 사용한 농축 방법을 연구하였다. 막다른 미세유로의 공간 제약적 구조를 통해 유체역학적 안정성을 확보할 수 있으며, 분석 물질의 농축 지점이 이온 공핍 영역의 충격 전단과 일치함을 수치적으로 확인하였다. 또한 농축 공정의 핵심 인자로써 인가 전압과 미세유로의 체적 전하 농도를 변화시켜가며, 농축 물질의 전기동역학적 거동을 연구하였다. 본 연구의 결과는 현장 진단 검사(point-of-care)와 같은 초단시간의 농축을 필요로 하는 미세유체역학 장치에 유효한 기작으로 사용될 수 있을 것이다.

• 멤브레인
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• 제32권1호
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• pp.23-32
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• 2022

세균은 분리막, 식품 포장 필름 및 바이오 의료 기기와 같은 다양한 미생물 막의 표면 위에서 자란다. 미생물 막의 성장은 엑소폴리사카라이드의 복잡한 구조 형성과 밀접한 관련이 있다. 미생물 막이 항균제의 대량 수송의 어려움으로 성장하게 될 경우 항균효과는 급격하게 감소한다. 항균 활동을 활성화하기 위해서 막의 표면은 살균 특성이 있는 기능성 물질들로 변형, 코팅 또는 고정한다. 한 가지 아이디어는 막 표면에 양전하 이온을 도입하는 것이다. 양전하 이온인 4차 암모늄 그룹의 존재는 마그네슘이나 칼슘같이 세균 세포벽에 존재하는 2가 금속이온을 대체할 수 있다. 세포막 파괴의 효능은 표면환경에서 사용 가능한 작용제들의 이동성에 달려있다. 이 리뷰에서는 4차 암모늄 그룹, 헬라민(helamine), 쌍성이온(zwitterion)과 같이 여러 살생물제를 포함하고 있는 막들을 다룬다.

• 한국포장학회지
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• 제29권3호
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• pp.223-228
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• 2023

Sustainable energy supplies without the recharging and replacement of the charge storage device have become increasingly important. Among various energy harvesters, the triboelectric nanogenerator (TENG) has attracted considerable attention due to its high instantaneous output power, broad selection of available materials, eco-friendly and inexpensive fabrication process, and various working modes customized for target applications. In this study, the amount of voltage and current generated was measured by applying the PSD profile random vibration test of the electronic vibration tester and ISTA 3A according to the time of Anodized Aluminum Oxide (AAO) pore widening of the manufactured TENG device Teflon and AAO. The discharge and charging tests of the integrated module during the random simulated transport environment and the recognition distance of RFID were measured while agricultural products (onion) were loaded into the returnable folding plastic box. As a result, it was found that AAO alumina etching processing time to maximize TENG performance was optimal at 31 min in terms of voltage and current generation, and the integrated module applied with the TENG module showed a charging effect even during the continuous use of RFID, so the voltage was kept constant without discharge. In addition, the RFID recognition distance of the integrated module was measured as a maximum of 1.4 m. Therefore, it was found that the surface condition of AAO, a TENG element, has a great influence on the power generation of the integrated module, and due to the characteristics of TENG, the power generation increases as the surface dries, so it is judged that the power generation can be increased if the surface drying treatment (ozone treatment, etc.) of AAO is applied in the future.