• Environmental Engineering Research
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• 제21권3호
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• pp.311-317
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• 2016

A new type of biofilter packed with composite carriers was designed for tertiary denitrification of the secondary effluent with removal of both oxidized nitrogen and suspended solids (SS). At the empty bed residence time of 15 min and organic carbon to nitrate nitrogen ($C/NO_3-N$) ratios of 2, 1.5 and 1 g/g, the removal percentage of $NO_3-N$ was 67%, 58% and 36% in the ethanol biofilter, and was 61%, 43% and 26% in the acetate biofilter, respectively. The biofilters packed with composite carriers removed SS effectively, with the effluent turbidity in both biofilters of less than 3 NTU. During the operating cycle between the biofilter backwashings, the $NO_3-N$ removal percentage decreased initially after backwashing, and then gradually increased. Under $C/NO_3-N$ ratios of 2, 1.5 and 1 g/g, the $NO_3-N$ reduction rate was 1.75, 1.04 and $0.68g/m^2/d$ in the ethanol biofilter, and was 1.56, 1.07 and $0.76g/m^2/d$ in the acetate biofilter, respectively. In addition, during denitrification, the ratio of the consumed chemical oxygen demand to the removed $NO_3-N$ was 5.06-8.23 g/g in the ethanol biofilter, and was 4.26-8.6 g/g in the acetate biofilter.

• 산업경영시스템학회지
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• 제45권3호
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• pp.49-56
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• 2022

ROK Navy intends to secure the Korean-type aircraft carrier in order to effectively prepare for various future security threats. In general, the Korean national competency is considered to be at the level of having an aircraft carrier, but it is unclear what scale aircraft carrier would be appropriate. In this study, the efficiency was evaluated through the relative comparison between national competency(national power, economic power) and the scale of aircraft carriers, and the optimal scale of the Korean-type aircraft carrier that could be acquired was presented. A DEA(Data Envelopment Analysis) model was applied to aircraft carriers(19 aircraft carriers in 11 countries) currently in operation and scheduled to be possessed in the world. As input variables, CINC(Composite Index of National Capability) and GDP(Gross Domestic Product), which are the most widely used as indicators of national and economic power, and as output variables, the full-load displacement, length, and width of aircraft carriers were selected. ARIMA(short-term within 5 years) and simple regression(long-term over 5 years) were used to estimate the future national competency of each country at the time of aircraft carriers acquisition. The relative efficiency score of the Korean-type aircraft carrier currently being evaluated is 1.062, and it was evaluated as small-scale aircraft carrier compared to the national competency. Based on Korean national competency, the optimal scale of the Korean-type aircraft carrier calculated by aggregating benchmark groups, is 58,308.1 tons of full-load displacement, 279.4m in length, and 68.3m in width.

• Smart Structures and Systems
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• 제24권6호
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• pp.803-812
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• 2019

Triplex composite is an epoxy-bonded joint structure, which constitutes the secondary barrier in a liquefied natural gas (LNG) carrier. Defects in the triplex composite weaken its shear strength and may cause leakage of the LNG, thus compromising the structural integrity of the LNG carrier. This paper proposes an autonomous triplex composite inspection (ATCI) system for visualizing and classifying hidden defects in the triplex composite installed inside an LNG carrier. First, heat energy is generated on the surface of the triplex composite using halogen lamps, and the corresponding heat response is measured by an infrared (IR) camera. Next, the region of interest (ROI) is traced and noise components are removed to minimize false indications of defects. After a defect is identified, it is classified as internal void or uncured adhesive and its size and shape are quantified and visualized, respectively. The proposed ATCI system allows the fully automated and contactless detection, classification, and quantification of hidden defects inside the triplex composite. The effectiveness of the proposed ATCI system is validated using the data obtained from actual triplex composite installed in an LNG carrier membrane system.

• 한국통신학회논문지
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• 제38A권6호
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• pp.512-519
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• 2013

본 논문에서는 합성 이진 옵셋 반송파를 (composite binary offset carrier: CBOC) 위한 새로운 비모호 상관함수를 제안한다. 먼저, CBOC 신호의 부반송파를 네 개의 부분 부반송파의 합으로 해석하고, 각 부분 부반송파들과 수신 신호의 부분 상관들을 생성한다. 이후 생성된 부분 상관을 재조합하여 날카로운 주 첨두를 갖는 새로운 비모호 상관함수를 생성한다. 모의실험의 결과로부터 신호 추적에 제안한 상관함수를 이용한 경우 기존 상관함수들을 이용한 경우보다 더욱 향상된 추적 오류 표준편차와 다중 경로 오류 포락선을 가짐을 확인한다.

• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.50-51
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• 1995

The swelling behavior of hyddrogels has been interested in many applications of drug carriers. These gels show reversible swelling changes in response to pH, electric currcnt, and temperature. Among others, the temperature-responsive behavior of poly(N-isopropylacrylanxide) (p(NIPAAm)) was studied, because a lower critical solution temperature(LCST) is in the vicinity of 32$\circ$C, and remarkable temperature-response can be obtained. We propose a novel composite membrane, which is appropriate for transporting drug ingredients above the transition temperature. Our object was to design a high permeation system above the shrinking temperature of p(NIPAAm). The membrane was composed of a matrix polymer and thermosensitive p(NIPAAm) hydrogel. The flux pattern of 4-acctamidophen through membrane in response of temperature was opposite to that of p(NIPAAm) membrane.

• Composites Research
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• 제24권3호
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• pp.39-45
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• 2011

접착제에 의한 접합은 일반적으로 구조물의 접합에 널리 사용되고 있다. 폴리우레탄 접착제와 에폭시 접착제는 현재 극저온에서 운항되고 있는 LNG 선박의 화물창에 적용되고 있다. 본 연구에서는 화물창용 소재인 트리플엑스와 폴리우레탄 및 에폭시 접착제와의 상온과 극저온에서의 접착강도를 평가하였다. 연구결과 모든 접착시스템에서 극저온에서 박리강도의 감소가 있었으며 그 원인은 접착제마다 다르게 검토되었다. 결과적으로는 폴리우레탄 접착제와 트리플엑스가 극저온에서의 강도 값이 에폭시에 비해 우수하였으며 LNG 선과 같은 극저온 환경에 접합한 것으로 평가되었다.

• Carbon letters
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• 제24권
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• pp.41-46
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• 2017

The microstructure, flexural properties, electrical conductivity, thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites filled with multi-walled carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnPs) and CNT-xGnP hybrid filler were investigated. The EMI SE of the CNT-xGnP hybrid composite was higher than 25 dB at 100 MHz while that of the xGnP based composite was almost zero. The flexural modulus of the CNT-xGnP based epoxy composite continuously increased to 3.32 GPa with combined filler content up to 10 wt% while that of the CNT based epoxy composites slightly decreased to 1.96 GPa at 4 wt% CNT, and dropped to 1.57 GPa at 5 wt% loading, which is lower than that of epoxy. The CNT and CNT-xGnP samples had the same EMI SE at the same surface resistivity, because samples with the same surface conductivity have the same amount of the charge carriers.

• 대한화학회지
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• 제56권4호
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• pp.473-477
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• 2012

The novel chitosan-based thermosensitive hydrogels were prepared as control-releasing drug carriers. N-carboxyethyl chitosan (ACS) was synthesized by microwave heating for 1 h through Michael addition of CS to acrylic acid in a grafting yield of 52.97%, which was proved to be a faster and more efficient way than ordinary methods. 5-Fu was modified with formaldehyde to synthesize N,N'-Bis(hydroxymethyl)-5-fluorouracil (5-Fu-OH). Then an esterification was performed using ACS and 5-Fu-OH to give 5-Fu-ACS. The new thermosensitive hydrogels were prepared by adding sodium glycerophosphate to the solution of compounds under a certain constant temperature. Simultaneously, the hydrogels' swelling rate, in vitro drug release rate and thermosensitive were studied, and found that the 5-Fu-ACS composite hydrogel had more excellent releasing effect, higher drug loading and better thermosensitive.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1047-1052
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• 2003

Controlling carrier transport in light emitting polymers is extremely important for their efficient use in organic opto-electronic devices [1]. Here we show that the interactions between single wall carbon nanotubes (SWNTs) and conjugated polymers can be used to modify the overall mobility of charge carriers within nanotube-polymer nanocomposites. By using a unique, double emitting-organic light emitting diodes (DE-OLEDs) structure. we have characterized the hole transport within electroluminescent nanocomposites (nanotubes in poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) or PmPV). We have shown using this idea that single devices with color tunability can be fabricated. It is seen that SWNTs in PmPV are responsible for hole trapping, leading to shifts in the emission wavelengths. Our results could lead to improved organic optical amplifiers, semiconducting devices, and displays.

• 한국표면공학회지
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• 제47권5호
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• pp.244-251
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• 2014

In recent years, self-healing coatings have been the subject of increasing interest. The ability of such coatings to self-repair local damage caused by external factors is a major factor contributing to their attractiveness. Metals are extensively used in modern society in a range of applications from infrastructure to aircraft to consumer products. The protection of metals, primarily from corrosion has been an active area of materials science for many years. The aim of this review is the demonstration for recent progress achieved in the development of carrier-based self-healing coatings for the protection of metals. This review mainly covers the reports published after 2010. Two main types of carriers for corrosion inhibitors or healing agents-polymer capsules and porous composite inorganic nanoparticles-are described.