본 연구는 수출용 큰느타리버섯의 선도 유지 및 저장성 증대를 위한 배지 적합 질소함량과 생육온도 조건을 설정 하고자 하였다. 배지 질소함량 1.5%, 1.8%, 2.1%, 2.4% 및 생육온도 15 ̊C, 12 ̊C, 9 ̊C 조건별로 자실체의 생육특성, 수확 후 냉장저장기간 동안의 가스농도, 자실체 품질 변화를 조사하였다. 대직경과 중량은 생육온도와 관계없이 질소함량이 높아질수록 증가하는 경향을 보였으며 병 당 중량은 12 o C, T-N 2.4% 조건에서 149.5 g으로 가장 높았다. 갓 색은 배지 질소함량과 관계없이 온도가 낮아 질수록 색도(L)가 낮아져 갓 색이 진해졌다. 저장기간에 따른 봉지 내 가스농도 변화는 9 ̊C, T-N 2.1% 조건에서 산도 농도가 가장 오래 유지되었다. 달관조사에 의한 자실체 품질평가에서 배지 질소함량에 따른 차이는 나타나지 않았고 저장기간 28일까지 이취, 변색, 부패 정도는 15 ̊C와 9 ̊C가 유사하게 나타났다.

느타리 ‘흑타리’ 품종의 배양 중 고온스트레스에 의해 발생되는 미발이 현상을 구명하기 위하여 배양온도에 따른 생육차이를 조사하였다. PDA 배지에서‘흑타리’의 적정생육온도는 23~26 ̊C였고, 균사생장속도는 ‘춘추2호’에 비하여 빠른편이었다. 병내 배지온도는 초기에 상승하여 배양 중반에 최고점에 도달한 후 온도가 하강하였다. 배양 온도가 높을수록 배양기간은 짧아졌다. 배양온도 20 ̊C 처리구에서 배양기간은 25일 정도 소요되었으며, 미발이율은 1.8%, 수량은 139.4 g/병을 나타내었다. 배양온도 24 ̊C 처리구에서 배양기간은 20일 정도 소요되었으며, 미발이율은 4.2%, 병당수량은 132.1 g/병을 나타내었다. 배양온도 16 ̊C와 28 ̊C처리구에서는 미발이율이 증가되었고 수량이 감소하였다. 이 결과를 바탕으로 농가에서 배양온도와 미발이율의 관계를 조사하였다. 배양실 온도를 18 ̊C로 설정하고 배지품온을 28 ̊C 미만으로 관리하는 농가는 미발이율이 0.3~0.8%를 나타내었다. 배양실내의 온도가 20 ̊C 이상이며 환기가 잘 이루어지지 않은 농가에서는 미발이율이 3.5% 정도 발생되었다. 배양실 온도가 19 ̊C이며 배지 최고 품온이 31.3 ̊C까지 상승하는 농가는 미발이율이 8.2%로 높게 나타났다. 배양중 병내부 온도가 28 ̊C이상 상승하고 배양실내의 환기가 잘 이루어지지 않을 경우 미발이율이 증가하고 수량이 감소되는 경향을 보였다. 결과적으로, 배양실은 배지품온이 28 ̊C 이상 상승하지 않도록 배양실 내부의 공기를 지속적으로 순환시키고, 배양공간에 맞는 최적의 배양량을 넣어 관리하여야 한다.

본 연구에서는 전처리방법별로 잎새버섯차를 제조하여 차의 pH, 색도 등의 품질과 아미노산 및 항산화활성을 분석하여 비교하였다. 건조, 증숙, 보온처리 버섯차를 제조 하여 추출액의 품질을 조사한 결과 건조와 증숙처리 차의 당도, 고형분, 질소함량 차이는 없었고 보온처리 차의 값이 다른 처리에 비해 높았다. 버섯차의 색도는 보온처리에서 가장 진하고 어두웠으며 보온처리 차가 462.9 mg/L 로 총 아미노산 함량이 1.8배 이상 높아 보온처리에 의한 차의 추출성분 변화가 있음을 확인할 수 있었다. 보온처리 버섯차의 총 폴리페놀 함량은 14.6 mg/g, 총 플라보노 이드 함량은 2.2 mg/g으로 증가하였고 페놀성 화합물의 증가로 DPPH와 ABTS 라디칼 소거활성도 증가하였다. 또한 맛의 기호도도 7.0으로 소폭 증가하여 보온처리는 잎새버섯의 영양성분과 항산화활성의 추출을 용이하도록 하고 관능적 품질도 향상시킬 수 있는 것으로 판단되었다.

In this study, the effects of Co content on the microstructure and Charpy impact properties of Fe-Cr-W ferritic/martensitic oxide dispersion strengthened (F/M ODS) steels are investigated. F/M ODS steels with 0–5 wt% Co are fabricated by mechanical alloying, followed by hot isostatic pressing, hot-rolling, and normalizing/tempering heat treatment. All the steels commonly exhibit two-phase microstructures consisting of ferrite and tempered martensite. The volume fraction of ferrite increases with the increase in the Co content, since the Co element considerably lowers the hardenability of the F/M ODS steel. Despite the lowest volume fraction of tempered martensite, the F/M ODS steel with 5 wt% Co shows the highest micro-Vickers hardness, owing to the solid solution-hardening effect of the alloyed Co. The high hardness of the steel improves the resistance to fracture initiation, thereby resulting in the enhanced fracture initiation energy in a Charpy impact test at – 40oC. Furthermore, the addition of Co suppresses the formation of coarse oxide inclusions in the F/M ODS steel, while simultaneously providing a high resistance to fracture propagation. Owing to these combined effects of Co, the Charpy impact energy of the F/M ODS steel increases gradually with the increase in the Co content.

In this study, the effect of tempering on the stretch-flangeability is investigated in 980 MPa grade dual-phase steel consisting of ferrite and martensite phases. During tempering at 300 oC, the strength of ferrite increases due to the pinning of dislocations by carbon atoms released from martensite, while martensite is softened as a consequence of a reduction in its carbon super-saturation. This strength variation results in a considerable increase in yield strength of the steel, without loss of tensile strength. The hole expansion test shows that steel tempered for 20 min (T20 steel) exhibits a higher hole expansion ratio than that of steel without tempering (T0 steel). In T0 steel, severe plastic localization in ferrite causes easy pore formation at the ferrite-martensite interface and subsequent brittle crack propagation through the highly deformed ferrite area during hole expansion testing; this propagation is mainly attributed to the large difference in hardness between ferrite and martensite. When the difference in hardness is not so large (T20 steel), on the other hand, tempered martensite can be considerably deformed together with ferrite, thereby delaying pore formation and hindering crack propagation by crack blunting. Eventually, these different deformation and fracture behaviors contribute to the superior stretch-flangeability of T20 steel.

This study conducted the experiment for the development of the low pressure type SCR system. The experimental equipment of SCR system was installed, which was widely used as the nitrogen oxides abatement system, and the demonstration experiment was conducted to see that it met the Tier III regulation according to the IMO NOx Technical Code. The SCR system demonstration experiment was divided into three stages: SCR system component operation test, engine parameter test by engine load, and NOx abatement performance and ammonia slip verification test. The final performance of the SCR system was verified through analysis of NOx abatement performance and ammonia slip test results for each load variation.

In this study, effects of carbon and nickel on microstructure and low temperature Charpy impact properties of HSLA (high strength low alloy) steels are investigated. To understand the complex phase transformation behavior of HSLA steels with high strength and toughness before and after welding processes, three kinds of HSLA steels are fabricated by varying the carbon and nickel content. Microstructure analysis, low temperature Charpy impact test, and Vickers hardness test are performed for the base metals and CGHAZ (coarse-grain heat affected zone) specimens. The specimens with the lowest carbon and nickel content have the highest volume fraction of AF, the lowest volume fraction of GB, and the smallest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the highest. The specimens with increased carbon and nickel content have the lowest volume fraction of AF, the highest volume fraction of GB, and the largest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the lowest.

Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.

PURPOSES : The use of hydrated lime or other liquid anti-stripping agents (ASA) is the most common method of improving the moisture susceptibility of asphalt mixes. ASAs are also known to have an anti-aging effect, according to several researchers. Therefore, the use of ASAs is expected to enhance the stability of asphalt pavements. The purpose of this study is to investigate the anti-aging effect of ASAs that are found in the domestic market. METHODS : In this study, an asphalt binder and a mixture mixed with typical domestic solid and liquid ASAs were prepared and aged to evaluate the physicochemical changes. A liquid additive developed by a Korean oil refinery was used as the liquid ASA, and hydrated lime was utilized as the solid ASA. The aging process of the asphalt was determined in the laboratroy based on previous studies to simulate the aging process inh te field. RESULTS : The result of the laboratory experiment indicates that both the solid and liquid ASAs have an anti-aging effect. Moreover, the liquid additive performed relatively better than the hydrated lime. CONCLUSIONS : If ASAs have an anti-aging effect in addition to the anti-stripping function, it is expected to improve the stability of the asphalt pavement significantly. However, few studies have been carried out on the anti-aging effect of ASAs found in the domestic market. In this study, we conducted a fundamental study on the anti-aging effect to help in the selection and use of ASAs in the domestic asphalt-paving industry.

In this study, two types of thick steel plates are prepared by controlling carbon equivalent and nickel content, and their microstructures are analyzed. Tensile tests, Vickers hardness tests, and Charpy impact tests are conducted to investigate the correlation between microstructure and mechanical properties of the steels. The H steel, which has high carbon equivalent and nickel content, has lower volume fraction of granular bainite (GB) and smaller GB packet size than those of L steel, which has low carbon equivalent and nickel content. However, the volume fraction of secondary phases is higher in the H steel than in the L steel. As a result, the strength of the L steel is higher than that of the H steel, while the Charpy absorbed energy at -40 °C is higher than that of the L steel. The heat affected zone (HAZ) simulated H-H specimen has higher volume fraction of acicular ferrite (AF) and lower volume fraction of GB than the HAZ simulated L-H specimen. In addition, the grain size of AF and the packet sizes of GB and BF are smaller in the H-H specimen than in the L-H specimen. For this reason, the Charpy absorbed energy at -20 °C is higher for the H-H specimen than for the L-H specimen.

본 연구에서 생력화가 가능하면서 친환경적인 재배법을 개발하고자 병, 상자를 이용하여 표고의 재배적 특성 및 자실체 생산성을 분석하였다. 재배용기별 배양기간은 병에서 배양된 처리구가 30일, 상자에서의 배양이 35일로 나타났고, 갈변기간은 병 재배가 25일, 상자 재배가 40일 이었으며, 병 배양 후 상자재배가 50일로 가장 길었다. 전체 재배기간은 병이 75일, 상자가 90일, 병 배양 후 상자 재배방식이 105일로 가장 길었다. 재배방식별 버섯 발이 수는 상자 17.8개, 병 배양후 상자재배 14.7개, 병 1개 순으로, 자실체 생산성에도 영향을 끼쳐 상자재배는 945 g, 병 배양 후 상자재배 638 g, 병재배가 70 g으로 나타났다. 건조 배지량별 신선버섯 수량(BE, %)은 상자재배가 32.7%, 병 재배가 24.3%, 병 배양 후 상자재배가 22.1% 순으로 상자재배의 자실체 수량성이 가장 우수하였다. 따라서 상자재배는 갈변기간의 단축과 버섯 수량성에서 병 재배, 병 배양후 상자재배 방식보다 유리한 장점이 있어 친환경 생력화 재배법 개발 가능성을 보여주었다.

In this study, we investigate the relationship between the peeling behavior of the backsheet of a photovoltaic(PV) module and its surface temperature in order facilitate removal of the backsheet from the PV module. At low temperatures, the backsheet does not peel off whereas, at high temperatures, part of the backsheet remains on the surface of the PV module after the peeling process. The backsheet material remaining on the surface of the PV module is confirmed by X-ray diffraction(XRD) analysis to be poly-ethylene(PE). Differential scanning calorimetry(DSC) is also performed to investigate the interfacial characteristics of the layers of the PV module. In particular, DSC provides the melting temperature(Tm) of laminated ethylene vinyl acetate(EVA) and of the backsheet on the PV module. It is found that the backsheet does not peel off below the Tm of ethylene of EVA, while the PE layer of the backsheet remains on the surface of the PV module above the Tm of the PE. Thus, the backsheet is best removed at a temperature between the Tm of ethylene and that of PE layer.

In this study, using a wet chemical process, we evaluate the effectiveness of different solution concentrations in removing layers from a solar cell, which is necessary for recovery of high-purity silicon . A 4-step wet etching process is applied to a 6-inch back surface field(BSF) solar cell. The metal electrode is removed in the first and second steps of the process, and the anti-reflection coating(ARC) is removed in the third step. In the fourth step, high purity silicon is recovered by simultaneously removing the emitter and the BSF layer from the solar cell. It is confirmed by inductively coupled plasma mass spectroscopy(ICP-MS) and secondary ion mass spectroscopy(SIMS) analyses that the effectiveness of layer removal increases with increasing chemical concentrations. The purity of silicon recovered through the process, using the optimal concentration for each process, is analyzed using inductively coupled plasma atomic emission spectroscopy(ICP-AES). In addition, the silicon wafer is recovered through optimum etching conditions for silicon recovery, and the solar cell is remanufactured using this recovered silicon wafer. The efficiency of the remanufactured solar cell is very similar to that of a commercial wafer-based solar cell, and sufficient for use in the PV industry.

본 논문에서는 압입시험을 통해서 초탄성 재료 물성치를 평가하는 간단한 방법을 제시하였다. 초탄성 재료 모델 중, 3개의 물성치(C10, C20, C30)를 가지는 Yeoh 모델을 선택하여 주연신률로 표현되는 변형률 에너지 밀도를 적용하였다. Yeoh 물성치를 변화시키며, 구형 압입시험 유한요소해석을 수행하여 압입자 반력-변위 곡선을 획득하였다. 압입자 반력-변위 곡선을 3차 다항식으로 근사하였고, 이 다항식을 물성치(C10, C20, C30)의 3차 곱으로 근사된 3차 다항식으로 표현하였다. 압입자 반력-변위 곡선 근사를 위해 회귀분석을 진행하여 수식들의 계수를 결정하였으며, 이 회귀식을 이용하여 초탄성 재료의 물성치를 평가 하였다. 초탄성 재료 물성치 평가를 수행하고 오차를 비교하여 유효성을 보여 주었다.