In order to produce size-controllable Ag nanoparticles and a nanomesh-patterned Si substrate, we introduce a rapid thermal annealing(RTA) method and a metal assisted chemical etching(MCE) process. Ag nanoparticles were self-organized from a thin Ag film on a Si substrate through the RTA process. The mean diameter of the nanoparticles was modulated by changing the thickness of the Ag film. Furthermore, we controlled the surface energy of the Si substrate by changing the Ar or H2 ambient gas during the RTA process, and the modified surface energy was evaluated through water contact angle test. A smaller mean diameter of Ag nanoparticles was obtained under H2 gas at RTA, compared to that under Ar, from the same thickness of Ag thin film. This result was observed by SEM and summarized by statistical analysis. The mechanism of this result was determined by the surface energy change caused by the chemical reaction between the Si substrate and H2. The change of the surface energy affected on uniformity in the MCE process using Ag nanoparticles as catalyst. The nanoparticles formed under ambient Ar, having high surface energy, randomly moved in the lateral direction on the substrate even though the etching solution consisting of 10 % HF and 0.12 % H2O2 was cooled down to -20˚C to minimize thermal energy, which could act as the driving force of movement. On the other hand, the nanoparticles thermally treated under ambient H2 had low surface energy as the surface of the Si substrate reacted with H2. That's why the Ag nanoparticles could keep their pattern and vertically etch the Si substrate during MCE.

An effect of thermal annealing on activating phosphorus (P) atoms in ZnO nanorods (NR) grown using a hydrothermal process was investigated. NH4H2PO4 used as a dopant source reacted with Zn2+ ions and Zn3(PO4)2 sediment was produced in the solution. The fact that most of the input P elements are concentrated in the Zn3(PO4)2 sediment was confirmed using an energy dispersive spectrometer (EDS). After the hydrothermal process, ZnO NRs were synthesized and their PL peaks were exhibited at 405 and 500 nm because P atoms diffused to the ZnO crystal from the Zn3(PO4)2 particles. The solubility of the Zn3(PO4)2 initially formed sediment varied with the concentration of NH4OH. Before annealing, both the structural and the optical properties of the P-doped ZnO NR were changed by the variation of P doping concentration, which affected the ZnO lattice parameters. At low doping concentration of phosphorus in ZnO crystal, it was determined that a phosphorus atom substituted for a Zn site and interacted with two VZn, resulting in a PZn-2VZn complex, which is responsible for p-type conduction. After annealing, a shift of the PL peak was found to have occurred due to the unstable P doping state at high concentration of P, whereas at low concentration there was little shift of PL peak due to the stable P doping state.

Si Nanowire (NW) field effect transistors (FETs) were fabricated on hard Si and flexible polyimide (PI) substrates, and their electrical characteristics were compared. Si NWs used as channels were synthesized by electroless etching method at low temperature, and these NWs were refined using a centrifugation method to get the NWs to have an optimal diameter and length for FETs. The gate insulator was poly(4-vinylphenol) (PVP), prepared using a spin-coating method on the PI substrate. Gold was used as electrodes whose gap was 8 μm. These gold electrodes were deposited using a thermal evaporator. Current-voltage (I-V) characteristics of the device were measured using a semiconductor analyzer, HP-4145B. The electrical properties of the device were characterized through hole mobility, Ion/Ioff ratio and threshold voltage. The results showed that the electrical properties of the TFTs on PVP were similar to those of TFTs on SiO2. The bending durability of SiNWs TFTs on PI substrate was also studied with increasing bending times. The results showed that the electrical properties were maintained until the sample was folded about 500 times. But, after more than 1000 bending tests, drain current showed a rapid decrease due to the defects caused by the roughness of the surface of the Si NWs and mismatches of the Si NWs with electrodes.

Transparent conductive films of single wall carbon nanotube (SWCNT) were prepared by spray coating method. The effect of acid treatment on the SWCNT films was investigated. The field emission scanning electron microscope (FESEM) shows that acid treatment can remove dispersing agent. The electrical and optical properties of acid-treated films were enhanced compared with those of as deposited SWCNT films. Nitric acid (HNO3), sulfuric acid (H2SO4), nitric acid:sulfuric acid (3:1) were used for post treatment. Although all solutions reduced sheet resistance of CNT films, nitric acid can improve electrical characteristics efficiently. During acid treatment, transmittance was increased continuously with time. But the sheet resistance was decreased for the first 20 minutes and then increased again. Post-treated SWCNT films were transparent (85%) in the visible range with sheet resistance of about 162Ω/sq. In this paper we discuss simple fabrication, which is suitable for different types of large-scale substrates and simple processes to improve properties of SWCNT films.

Inorganic-organic composite thin-film-transistors (TFTs) of ZnO nanowire/Poly(3-hexylthiophene)(P3HT) were investigated by changing the nanowire densities inside the composites. Crystalline ZnO nanowireswere synthesized via an aqueous solution method at a low temperature, and the nanowire densities inside thecomposites were controlled by changing the ultrasonifiaction time. The channel layers were prepared withcomposites by spin-coating at 2000rpm, which was followed by annealing in a vacuum at 100oC for 10 hours.Au/inorganic-organic composite layer/SiO2 structures were fabricated and the mobility, Ion/Ioff ratio, andthreshold voltage were then measured to analyze the electrical characteristics of the channel layer. Comparedwith a P3HT TFT, the electrical properties of TFT were found to be improved after increasing the nanowiredensity inside the composites. The mobility of the P3HT TFT was approximately 10-4cm2/V·s. However, themobility of the ZnO nanowire/P3HT composite TFT was increased by two orders compared to that of theP3HT TFT. In terms of the Ion/Ioff ratio, the composite device showed a two-fold increase compared to thatof the P3HT TFT.

본 연구에서는 지반공학적 문제를 발생시키는 고유기질토의 역학적 특성을 알아보고자 실내 시험을 실시하였다. 사용된 고화제는 산업부산물을 재이용한 고화제(NSB)이며 역학적 특성을 비교하고자 고로슬래그시멘트(GSC)를 이용하였다. 사용된 점토는 카오리나이트이며, 휴믹산을 유기물로 이용하여 혼합하였다. 시험 결과 pH는 유기물의 함량이 증가할수록, 양생일이 증가할수록 감소하였다. 일축압축강도는 휴믹산이 증가될수록 감소하였으며, 파괴시 축 변형률은 휴믹산이 증가할수록 증가되는 경향을 나타내었다.

하수슬러지 자원화 처리 방안 중 하나인 고화처리는 시멘트 및 생석회 등의 무기계 재료를 고화공정의 첨가제로 사용하여 하수슬러지를 고화시켜 인공토양을 제조하는 기술로, 다른 자원화 방법과 비교하여 에너지 사용량이 적은 공법으로 재자원화율이 가장 높은 육상처리 방법이라 말할 수 있다. 환경부 국가환경기술정보센터의 자료에 따르면 2012년 4월 현재 국내 운영 중인 총 89개의 하수슬러지 처리시설 중 고화처리 시설은 12개소이며, 처리 가능 시설 용량은 2,668톤/일으로 전체 시설의 약 30%를 차지하고 있다. 본 연구에서는 슬래그 활성화 메커니즘을 기반으로 하고 자극제로 고칼슘 플라이애시인 열병합발전소 소각재와 제지슬러지 소각재를 활용하여 제조한 하수슬러지 고화재 CMD-SOIL 1000 (형원길 외, 폐기물학회 2012)을 국내 4곳의 하수슬러지 자원화 시설에 적용하여 설비 운용성을 평가하고, 최종 배출 고화물을 매립지의 복토재로 재이용하기 위해 관련 규정에 의거한 적합성을 평가하였다. 평가 결과 자원화 시설에서 설비 가동성과 관련하여 요구하는 항목인 고화재 이송 여부, 시간당 혼합 배치 수 및 배출량 그리고 하수슬러지 중량에 대한 고화재 적정 혼합비율을 모두 만족시키는 것을 확인할 수 있었다. 또한 유기성 오니를 고화하여 생산한 고화처리물을 매립시설의 복토재로 재활용하기 위한 규정인 ‘폐기물관리법 시행규칙 별표 5의 2’ 에서 정한 수소이온농도 12.4 이하, 수분함량 50% 이하, 투수계수 1.0×10-7cm/sec 이상 1.0×10-3cm/sec 이하, 일축압축강도 0.10MPa 이상 그리고 유해물질 함량 기준인 ‘토양환경보전법 시행규칙 제1조 5’ 에 따른 토양오염우려기준 중 2지역 이내인 기준치를 모두 만족하여, CMD-SOIL 1000은 기존 국내 하수슬러지 자원화 설비에 적합한 하수슬러지 고화재인 것으로 판단되었다.

하수슬러지 자원화 처리 방안은 소각, 건조, 탄화, 용융, 고화, 연료화, 퇴비화 등이 제안되고 있다. 그 중 고화처리는 다른 공법에 비해 건설비 절감, 처리공정 단순, 환경영향이 적다는 특징을 가지고 있다.하수슬러지의 고화처리 시 고화재 투입으로 인한 건조 중량 증가가 단점으로 언급되고 있으나, 하수슬러지를 이용하여 제조한 인공토양은 흙을 대체할 건설재료로 활용이 가능하여 천연토사의 절감과 인공토양의 판매로 인한 경제적인 장점을 지니고 있다. 본 연구에서는 슬래그 활성화 메커니즘을 기반으로 하고 자극제로 고칼슘 플라이애시를 활용하여 제조한 하수슬러지 고화재 CMD-SOIL 1000(형원길 외, 폐기물학회 2012)을 국내 하수슬러지 자원화 설비에 적용하여 배출된 고화물의 유효 자원으로써의 재활용 가능성을 평가하고자 하였다. 상기 고화물의 매립시설 복토재로 품질 적합성(폐기물관리법 시행규칙)을 선행 연구결과 확인할 수 있었으며, 다짐시험을 실시한 결과 연약지반 판정기준의 사질지반 기준(도로설계 편람, 2000)을 상회하는 값인 최적 함수비 49.1%와 최대 건조밀도 1.06g/cm²를 나타내어 지반침하에 대한 안정성 확보가 가능한 것으로 판단되었다. 또한 고화물과 자연 상태의 토사를 일정한 비율로 혼합한 토양에 페레니얼 그라이스를 파종하여 생육 특성을 살핀 결과, 발아초기에는 자연 상태의 토사의 비율이 높을수록 개체수가 많고 성장속도의 차이가 있었으나 재령이 지날수록 육안으로 관찰되는 차이가 없었으며, 파종 56일 이후에는 자연 상태의 토사만을 활용한 경우와 동일한 생육 상황이 관찰되었다. 따라서 고칼슘 플라이애시를 적용한 하수슬러지 고화물은 매립지 복토재 외에도 토지개량제 및 기반 성토재 등의 용도로 활용이 가능한 것으로 판단되었다.

This study is regarding the property evaluation of mortar for ‘ONDOL’ floor (Korean floor heating system) finishing with reduced drying and shrinking properties to use it in the form of ready-mixed concrete mortar. The mortar utilized furnace slag based inorganic binding agent NSB, which has the characteristic of CaO included in HCFA generated from the fluidized-bed-firing power plant. Based on the test results, it is judged that mortar for ‘ONDOL’ floor finishing based on NSB including HCFA can be used in the form of ready-mixed concrete. According to site test construction, the flow property was relatively poor because fine gravel at ready-mixed concrete factory was used. However, since finishing property, crack resistance and water content are good, it is believed that it can be used at construction site in the form of ready-mixed concrete mortar. More study on adhesion property with floor plate would be required in the future.

This study aims to develop solidifying agents of sewage sludge using industrial By-Products and evaluate applicability of the solidified sewage sludge. The result of this study shows that it was possible to reduce water content of the cover materials to more than 50% in a short time as a result of the excellent hygroscopic function of inorganic binder made from industrial by-products and the granulation of sludge. The result suggests that the appropriate mixed ratio of (PSA + CPA) − (GBFS + SM1) − (SAS + SM2) is 60-25-15, and input ratio of solidifying agent is 48%, considering the applicability of the facilities, including mixing performance and availability of discharge, as well as the percentage of moisture content of the solidified sewage sludge, pH, and exothermic temperature. The solidified sewage sludge made using industrial by-products met more than the standard of unconfined compressive strength 0.5 kg/cm2 (as for cover materials 0.1 MPa) in 7 days due to ground granulated blast furnace slag, high-calcium fly ash, and SAS. As a result, valid resource recovery is possible through the land treatment of sewage sludge by inducing in-situ stabilization of heavy metals and property strengths through the reactivity of industrial by-products.