This paper investigates tensile characteristics of the stress aging heat-treated SM45C steel which are aging temperature at 250℃, 300℃, aging time at 1, 3 hours, and applied load at 300, 400N conditions by using acoustic emission. Most suitable aging condition was aging temperature 300℃, aging time 1 hour, and aging applied load 300N. And increased yield load 28.3% than non-treatment specimen in this condition. AE energy in elastic limit increased about 16.7 times than non-treatment specimen. When aging time is 3 hours, yield load decreased than other conditions that possibility is high to have itself defect on inside the specimen or coarse grain size precipitation is different in happened over-aging phenomenon. Especially, in case of 300℃, 3 hours and 400N condition appeared AE energy in elastic limit fairly high about 30 times than non-treatment specimen. This is considered by emit a lot of energies when material causes plastic deformation because the ductility increases on specimen by over-aging phenomenon.

The brilliant cresyl blue (BCB) has been used to select the developmental competent oocytes in pigs, goats and cows. Growing oocytes have a higher level of active glucose-6-phosphate dehydrogenase(G6PDH) compare to mature oocytes and are rarely stained compared to mature oocytes, because G6PDH converts BCB to colorless. First polar body extrusion regard as a guideline of meoisis completion. Selection of polar body extrude oocyte is more developmental competent to blastocyst than unselected. This study was conducted to compare the BCB test to the polar body extrusion on selection of developmental competent porcine oocytes for the production of blastocyst. Cumulus-Oocytes complex were exposed to 26uM BCB stain diluted in NCSU-23 for 90 min. There was no significant difference embryo development to blastocysts between BCB treated and not treated(19.58±1.99 vs 18.75±2.27 %), which means there was no detrimental effect of BCB exposure to oocytes. Normal fertilization is not differed among treatment groups from 70.0 to 78.4% development to blastocyst, beside polyspermy did not. To compare two different selection methods, BCB test and polar body extrusion, evaluate the developmental competent of IVP embryos. BCB+PB+(blue stained and polar body extruded, 20.71±0.45%) and BCB－PB+(colorless and polar body extruded, 20.04±1.29%) groups are significantly (p<0.05) higher developed than those of BCB+PB－(blue stained and no polar body, 13.24±0.73%) and BCB－PB－(colorless and no poladbody, 7.25±0.77%). These results showed that selection of polar body extruded oocytes method is more efficient than that of BCB test.

A study of fracture to material is getting interest in nuclear and aerospace industry as a viewpoint of safety. Acoustic emission (AE) is a non-destructive testing and new technology to evaluate safety on structures. In previous research continuously, all tensile tests on the pre-defected coupons were performed using the universal testing machine, which machine crosshead was move at a constant speed of 5mm/min. This study is to evaluate an AE source characterization of SM45C steel by using k-nearest neighbor classifier, k-NNC. For this, we used K-means clustering as an unsupervised learning method for obtained multi -variate AE main data sets, and we applied k-NNC as a supervised learning pattern recognition algorithm for obtained multi-variate AE working data sets. As a result, the criteria of Wilk's λ, D&B(Rij) & Tou are discussed.

To characterize testing bags for the interior parts and components of new vehicles, three types kinds of bags (Tedlar bag, Polyester Al bag, and PET bag) were selected and investigated.. All testing bags were initially purged with 5 L of pure nitrogen gas. Then, they were heated consecutively for four times in a chamber at 60 and 100℃ at hourlys intervals. Changes in background concentration levels of VOCs and HCHO were then measured. After the 4th heat treatment at 100℃, the background concentrations in PET bag were lower by 5 times than the ftrst time treatment. The results of PET bags were superior to the other bags under the same treatment conditions. Even without heat treatment test, the background concentrations of PET bag was also lower than the others by 2 to 6 times. Based on our results, it can be concluded that the PET bag is the most suitable for sample tests as it is physically the most stable along with the lowest background of all 3 sample bags with the least bias.

ZnO/ZnS core/shell nanocrystals (~5-7 nm in diameter) with a size close to the quantum confinement regime were successfully synthesized using polyol and thermolysis. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analyses reveal that they exist in a highly crystalline wurtzite structure. The ZnO/ZnS nanocrystals show significantly enhanced UV-light emission (~384 nm) due to effective surface passivation of the ZnO core, whereas the emission of green light (~550 nm) was almost negligible. They also showed slight photoluminescence (PL) red-shift, which is possibly due to further growth of the ZnO core and/or the extension of the electron wave function to the shell. The ZnO/ZnS core/shell nanocrystals demonstrate strong potential for use as low-cost UV-light emitting devices.

The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Monotonic simple tension and AE tests were conducted against the 3 kinds of welded specimen. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multi-variate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

A wax-typed pheromone dispenser has been developed and applied to control outbreak of the oriental fruit moth, Grapholita molesta, in apple orchard. To optimize its application technique, this study analyzed effect of different amounts of the pheromone dispenser on mating disruption (‘MD’) of G. molesta. Different pheromone dispenser amounts significantly influenced the MD effect assessed by cumulative male adult catches monitored respectively by sticky delta trap and food trap, and resulted in differential damage on host plants. In a field test during entire growing season, a standard amount (120 g per 0.117 ㏊) of wax-typed pheromone dispenser was proved to be effective to suppress outbreak of G. molesta adults and to prevent host plant damage as much as a current commercial MD product (Isomate<SUP>Ⓡ</SUP>). This study also demonstrated an effectiveness of deployment of food trap barriers around MD-treated area to prevent immigration of mated females from outside untreated areas. These results indicate that the wax-typed pheromone dispenser can be applied to control field G. molesta populations and its co-application with food trap barriers would be optimal to maximize MD efficacy.

This study was performed to analysis the concentration of TVOC, 5VOC and formaldehyde for building material of total 262 using 20L test chamber. The concentration of TVOC, 5VOC and formaldehyde were measured 1.001㎎/㎡･h, 43.032㎍/㎡･h, 0.012㎎/㎡･h, respectively. TVOC concentration of paint and floor covering occupied the largest concentration of the indoor building materials as 2.689㎎/㎡･h, 2.120㎎/㎡･h, respectively. 5VOC concentration of floor covering was measured 106.636㎍/㎡･h. Toulene and xylene were occupied the largest part of the 5VOC as 51.2% and 33.1%, respectively. The concentration of formaldehyde for furniture materials occupied the largest concentration of the indoor building material as 0.072㎎/㎡h.

"Sick car syndrome" is known as a syndrome having latent health damage caused by complex smell of the assorted chemicals such as PVC and ABS which was components of new car interior trim (sheet, dashboard, audio case, cable, safety glass, synthetic rubber, and adhesive). The impact of interior trim on VOC levels was evaluated by testing with leather or fabric trims. Concentrations of VOCs and formaldehyde (HCHO) discharged from the car interior trims (2 sheet covers and 1 headliner) fixed in the sample holder of the small chamber were analyzed quantitatively and qualitatively. Concentrations of TVOC and HCHO emitted from 3 samples increased with increasing temperature and time. Concentration of TVOC emitted from PVC foam leather was highest under experimental conditions.

The effects of the field emission property in relation to the surface morphology and adhesion force were investigated. The single-wall-nanotube-based cathode was obtained by use of an in-situ arc discharge synthesis method, a screen-printing method and a spray method. The morphologies of the formed emitter layers were very different. The emission stability and uniformity were dramatically improved by employing an in-situ arc discharge synthesis method. In this study, it was confirmed that the current stability and uniformity of the field emission of the cathode depend on the surface morphology and adhesion force of the emitters. The current stability of the field emission device was also studied through an electrical aging process by varying the current and electric field.

The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Simple tension and AE tests were conducted against the 3 kind of welding test specimens. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multivariate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver (Ag) powders as a bonding material between the CNTs and cathode electrodes. The effects of the powder size on the sintering behavior, the current density and emission image for CNT cathodes were investigated. As the diameter of the Ag powders decreases to 10 nm, the sintering temperature of the CNT cathode was lowered primarily due to the higher specific surface area of the Ag powders. In this study, it was demonstrated that nano-sized Ag powders can be feasibly used as a bonding material for a screen-printed CNT cathode, yielding a high current density and a uniform emission image.

We have determined the disk size of Be stars by using Hα emission. We observed spectra of Be stars with telescope in SNU, equipped with SB SGS (Santa Babara Self Guided Spectrograph) and CCD ST-8. The size of disk of Be stars was estimated with the Be star model of Grundstrom & Gies (2006). This study suggests that the medium resolution spectra taken with small telescope equipped with commercial spectrograph are useful to estimate the approximate size of the Hα emitting disk around Be stars.

실내 공기는 대기와는 달리 실내 건축 자재에서 유래된 물질로 오염될 수 있다. 본 연구는 실내자재인 카펫에서 방출되는 휘발성 유기화합물의 생물학적 영향을 평가하기 위하여 수행되었다. 카펫과 자주달개비 BNL 4430 꽃차례를 환경노출시험용기에 넣고 일정시간 노출을 실시하였고 흡착관의 VOCs에 대한 화학분석을 실시하였다. 화학분석결과 카펫에서는 12종의 VOCs가 방출되는 것이 확인되었으며 이중 스틸렌(71.9μg m-3)과 톨루엔(

In recent years, the number of complaints about indoor air pollution caused by volatile organic compounds(VOCs) has increased. It is important that evaluating and understanding emission of indoor air pollutant from building materials. The aim of this study was to evaluate emission test methods for liquid phase building materials such as paint, adhesive and sealant, and to determine the emission of total volatile organic compounds(TVOC) from liquid phase building material. The quantity of TVOC emission was measured by a gas chromatography/mass spectrometry (GC/MSD). It was found that liquid phase building materials were classified according to their use and ingredient. The TVOC concentration from oil-based paint was the highest among 8 groups of test materials. The unidentified volatile organic compounds occupied 83.0% of TVOC emission from test materials. The aliphatic hydrocarbons and aromatic hydrocarbons occupied 7.2%, 6.9% of TVOC, respectively. The concentration of TVOC decreased by an increase during emission test period. After 3 days, the concentration of TVOC from paint, adhesive and sealant were about half of the concentration at the first day. The ratio of concentration between 7 days and 1 day was 0.11～0.15 from water-based paint and 0.46～0.48 from epoxy adhesive.

SPG (Shirasu porous glass) 관형 막이 설치된 회분식 막유화 장치를 사용하여 이온성 약물이 담지된 단분산 polycaprolactone (PCL) 마이크로캡슐을 제조하기 위한 막유화 공정변수의 최적조건을 결정하였다. 마이크로캡슐에 담지된 이온성 약물로는 양이온성인 lidocaine-hydrochloride, 중성인 sodium salicylate와 음이온성인 4-acetaminophen의 3가지를 사용하였으며, PCL 마이크로캡슐로부터 이들 모델약물의 방출거동을 검토하였다. 캡슐제조에 사용된 PCL의 농도와 분자량, 막간 압력차, 분산상과 연속상에 첨가시킨 유화제의 농도, 연속상의 교반속도가 막유화법으로 제조된 PCL 캡슐의 크기와 크기분포에 미치는 영향을 검토하였다. 이들 공정변수의 조절을 통해 평균 크기 약 5 μm의 균일한 마이크로캡슐을 제조할 수 있었다. 약물 방출실험 결과 산성조건에서 알칼리조건으로 방출환경이 변화됨에 따라 약물 방출속도가 증가하였다.

고연소도 경수로사용후핵연료를 이용하여 voloxidation 및 소결 열처리 공정으로부터 세슘의 시간에 따른 방출 거동을 실험적으로 평가하였다. 사용후핵연료 voloxidation 공정에서는 fragment 형태의 시편을 사용하여 최대 의 산화 및 환원 분위기에 따른 세슘 방출 거동을 상호 비교하였으며, 소결 공정에서는 압분체를 이용하여 4% H2/Ar 환원분위기 에서 열처리 온도 변화에 따른 세슘방출 특성 변화를 분석하였다. 산화 분위기에서 fragment 형태의 사용후핵연료로부터 세슘 방출 온도 구간은 였으며, 환원 분위기에서 압분체로부터 방출 온도 구간은 로서, 산화에 의한 사용후핵 연료의 분말화가 세슘 방출 거동에 영향을 미치는 것으로 나타났다. 아울러 사용후핵 연료로부터 세슘 방출 거동에 영향을 미치는 주요 인자는 사용후핵 연료내 세슘 화합물의 화학적 형태뿐만 아니라 결정립 및 핵연료 표면으로의 확산 속도에 지배를 받음을 알 수 있었다.