나노마이크로 메쉬를 이용한 유회수 장치의 개발 및 성능평가

정경국,고종수,정영,박경택,박선기,윤정인,이두용 해양환경안전학회 2016 해양환경안전학회 학술발표대회 논문집 Vol.2016 No.11

나노 마이크로 메쉬를 이용한 유회수 장치

정경국,고종수,정영,최창준,박경택,손경득,박선기,이성종,윤정인,이두용 한국유체기계학회 2016 한국유체기계학회 학술대회 논문집 Vol.2016 No.06

Super Wear Resistant Nanostructured Superhydrophobic Surface

정경국,정영,박병건,최창준,고종수 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.4

In this study, a superhydrophobic nickel surface that is highly robust against repetitive rubbing is presented. We implanted carbon nanotubes (CNTs) to protect the surfaces from contacts. We show that the CNTs implanted in nickel do not easily detach from the surface and maintain superhydrophobicity despite harsh rubbing (40 kPa, 600 cycles) by 800 grit sandpaper; by contrast, surfaces prepared by typical nanofabrication methods are visibly damaged and lose superhydrophobicity after such treatment. The CNT-implanted nickel surfaces developed in this study are the most robust among nanostructured surfaces reported up to date.

Thermoelectric generator based on a bismuth-telluride alloy fabricated by addition of ethylene glycol

정경국,고종수 한국물리학회 2014 Current Applied Physics Vol.14 No.12

This paper introduces a new method to selectively fabricate n-type and p-type bismuth (Bi)-telluride (Te) thermoelectric materials by the rate of addition of ethylene glycol (EG) in the BieTe co-electrodeposition solution. As the amount of added EG is increased, the atomic ratio of Bi in the deposited BieTe alloy reached a slope of 0.463 (at.% of Bi/vol.% of EG), and increased in a linear manner. When the EG content reached approximately 20%v/v, the n-type material changed into a p-type. This change implies that adjusting the EG content in the electrodeposition solution affords simple control of the BieTe composition. To demonstrate the applicability of the developed thermoelectric materials, thermoelectric generators (TEGs) were fabricated using electrodeposited n-type (using solution without EG) and p-type (using solution with 30%v/v EG) BieTe alloys. The Seebeck voltage of the pair of n-type and p-type thermoelectric materials was 140 mV and the power generated from the pair was 24.36 nW at a 10 C temperature difference.

소화설비용 NOVEC가스의 분출유량에 미치는 노즐 형상의 영향

윤정인,정경국,김지성,김성윤,최재혁 해양환경안전학회 2018 해양환경안전학회 학술발표대회 논문집 Vol.2018 No.11

NOVEC가스 소화설비용 노즐 형상 설계에 대한 수치해석

윤정인,정경국,김지성,김성윤,노범석,최재혁 해양환경안전학회 2018 해양환경안전학회지 Vol.24 No.7

Clean fire extinguishing agents refer to chemical that can replace Halon 1211 and Halon 1310 according to the Montreal Protocol fermented to protect the Earth's ozone layer. In Korea and abroad, system standardization and performance evaluation of clean fire extinguishing agents are being carried out. This paper proposes an optimal nozzle shape by modeling and numerical analysis of various nozzle shapes based on general clean fire extinguishing system. The ejection speed of the nozzle can be improved by studying three - dimensional modeling of the nozzle for two shapes, Type A and B. Flow analysis was performed on the two types of nozzles and the gas velocity and pressure distribution were measured with different nozzle diameters. It was confirmed that the jetting speed was changed at the nozzle outlet according to the number and diameter of the nozzle holes. The flow rate increased with increasing the pressure regardless of the nozzle hole diameter. Based on the results obtained from the experiment, the K-factor value was deduced. Finally, a nozzle with a 12-hole structure with a 5-mm nozzle hole was proposed. 청정소화약제는 지구오존층 보호를 위해 발효된 몬트리올 의정서에 따라 할론 1211 및 할론 1310을 대체할 수 있는 약제를 말한다. 국·내외적으로는 청정소화약의 시스템 표준화와 성능평가가 수행되고 있다. 본 논문은 일반적인 청정소화약제 시스템을 바탕으로 다양한 노즐의 형상에 대한 모델링 및 수치해석을 수행하여 최적의 노즐 형상을 제안하였다. Type A와 B의 2가지 형상에 대한 노즐의 3차원 모델링을 통해 노즐의 분출속도가 개선될 수 있도록 하였다. 2가지 형상의 노즐에 대하여 유동해석을 실시하였으며 노즐의 홀 직경을 다르게 하여 가스속도 및 압력분포를 측정하였다. 측정결과 노즐 홀 수 및 직경에 따라 노즐출구에서 분출속도가 달라지는 것을 확인할 수 있었으며 노즐 홀 직경에 관계없이 유량은 압력이 증가함에 따라 증가하는 경향을 나타내었다. 실험을 통해 얻어진 결과를 바탕으로 노즐 직경이 5mm인 경우의 K-factor값이 101.8l/min·bar^-0.5임을 확인하였으며, 최종적으로 노즐 홀 5mm인 12개의 홀이 2층 구조로 되어있는 형상의 노즐을 제안하였다.

Capacitive Oil Detector Using Hydrophobic and Oleophilic PDMS Sponge

정영,정경국,박병건,고종수 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.5 No.2

In this study, we designed and fabricated a capacitive oil detector using a polydimethyl siloxane (PDMS) sponge and evaluated its performance. A PDMS sponge has a hydrophobic/oleophilic characteristic, which blocks water infiltration yet absorbs oil. The absorbed oil changes the detector capacitance between the two electrodes within the PDMS sponge. We used three primary types of marine fuel oils (diesel, crude oil, and heavy oil) to evaluate the performance of the fabricated oil detector. Diesel was detected in the shortest time, followed by crude oil and heavy oil. That is, oils with lower viscosity were detected more rapidly. The measured capacitance was the lowest for diesel and the highest for heavy oil. Oils with higher dielectric constants had a higher measured capacitance. Water did not seep into the microcavity of the capacitive oil detector until it reached a depth of 140 cm. We were able to detect the presence of an oil-film below 900 μm. The fabricated detector showed almost the same capacitance throughout the ten cycles of repeated cleaning and measurements.

선박 폐유 재활용 장치의 설계 및 열유동에 관한 수치적 해석

김홍중,박인만,정경국,윤정인,윤석훈,이원주,최재혁 해양환경안전학회 2018 해양환경안전학회 학술발표대회 논문집 Vol.2018 No.11

해상 광대역 통신시스템 개발

김지성,윤정인,정경국,김성윤,강희욱,이종률,손원일,김경남,이두용 한국마린엔지니어링학회 2018 한국마린엔지니어링학회지 Vol.42 No.4

This study aims to develop bridge equipment for terrestrial and maritime terminal stations and automatic tracking antenna systems for low-cost base stations. The tests were performed considering the bridging speed, hardware recovery, distance range and communication speed. The bridging speed test was conducted by installing a bridging device and an antenna, and it was confirmed that the existing antenna could be connected to the new antenna within 10 s if the connection was cut off because of signal interruption. The hardware recovery test method was used to install the bridge device, and it was confirmed that the time to reach the login screen by pressing the power button of the breeze device was within 60 s. The test method of the distance range test verified the communication status of the land base station and the repeater, and it was confirmed through the GPS equipped in the repeater that the distance between the land base station and the repeater was over 30 km. The test method of the communication speed test aimed to check the communication status by connecting to the site for the transmission test using the installed repeater. This test confirmed that the communication speed between the terrestrial base station and the repeater was over 1 Mbps at a 30 km distance. The experiment showed that in all tests, the bridging processing speed was 3.16 s; the hardware recovery time was 52.21 s; the communication distance was 32.26 km; and the communication speed for downloading was 6.35 Mbps, whereas that for uploading was 4.05 Mbps. The results of this study are expected to contribute to the development of a remote monitoring system 본 논문의 목적은 육상 및 해상 단말기지국용 브릿지 장비, 저가 보급형 기지국 자동추적 안테나 시스템을 개발하는 것이다. 시험은 브리징 처리속도, 하드웨어 복구, 통달거리 및 통신속도로 총 4가지를 기본적으로 실시하였다. 브리징처리속도 시험의 실험방법은 브리지 장비와 안테나를 설치하고 기존의 안테나가 신호단절로 인하여 연결이 끊어졌을 경우 10 초 이내에 새로운 안테나에 연결이 가능한지 확인하였다. 하드웨어 복구 시험의 실험방법은 브리지 장비를 설치하고 브리장비의 전원을 눌러 로그인 화면이 나올 때까지의 시간이 60 초 이내인지 확인하였다. 통달거리 시험의 실험방법은 육상 기지국과 중계기의 통신상태를 확인하고 중계기가 장착된 GPS를 통해 육상 기지국과 중계기의 거리가 30 km이상인지 확인하였다. 통신속도 시험의 실험방법은 설치된 중계기를 이용하여 전송시험을 위한 사이트에 접속하여 통신상태를 확인한 뒤 30 km거리에서 육상 기지국과 중계기의 통신속도가 1 Mbps이상인지 확인하였다. 실험 측정결과 브리징처리 속도 3.16 초, 하드웨어 복구시간 52.21 초, 통달거리 32.26 km, 통신속도 다운로드 6.35 Mbps, 업로드 4.05 Mbps로 4 가지 실험 모두 요구기준에 충족하여 적합 판정을 받았다. 본 연구에서 실험한 통신시스템의 4가지 성능이 목표치 이상을 충족하며 개발완료된 상태로 본 연구결과는 원격 모니터링 시스템(NMS) 개발에 기여할 수 있을 것으로 기대된다.

폴리우레아를 활용한 해상풍력 지지구조물 안티파울링 필름 개발

손진혁,강명보,정경국,한우범 한국풍력에너지학회 2024 풍력에너지저널 Vol.15 No.1

Bio-fouling has positive aspects that are used as a fish resource, but there are also negative aspects such as corrosion of the surface of the support structure, aesthetics and work safety problems. A specimen was produced using a polyurea material with excellent anti-fouling and methodology, and contact angle, high water pressure, adhesion, and real sea area tests were performed. As a result of measuring the contact angle of the specimen with a 10 cm x 10 cm area of polyurea, There was found to be an average of 124.4 ° at nine points. No surface damage was found even above 5 Mpa when high water pressure was sprayed, and adhesive strength of 300LSE adhesives was confirmed between 22.84 and 23.04 Mpa with an adhesion test. During the 6-month real sea area test, it was confirmed that about 17.24 % of the polyurea film was less generated than the comparison group.