This study was conducted to examine the microbiological quality indicators (total bacterial count and coliform count) and physicochemical quality indicators (pH, redness, volatile basic nitrogen [VBN] content) of meat according to various storage temperatures (20~15oC) and packaging methods (wrap, vacuum). Based on these results, we proposed a safe consumption period. Redness, pH, and VBN content were not considered appropriate for setting the expiration date, as the redness and pH of the meat after spoilage were better than the standard values for both vacuum and wrap packaging (p<0.05). Additionally, the VBN content at 2 and 4oC increased slightly (fresh level) until the initial time of spoilage (1.0×106 colony-forming unit [CFU]/cm2) and then increased rapidly thereafter. Therefore, the results were not consistent with microbial spoilage. When the decay point was evaluated based on the presence of microorganisms, vacuum packaging extended the storage period approximately 2.5-fold when compared with wrap packaging, and the meat could be stored at 2 or 4oC for 40 or 23 days, respectively. Therefore, to evaluate meat quality, microbial indicators should be considered first. The microbiological standards proposed in this study can be used for safety management during the distribution of meat. However, to ensure meat safety, additional investigations of appropriate indicators of freshness must be conducted.

농림축산검역본부는 해외해충 연구를 위해 밀폐능력을 갖춘 검역해충실험동을 구축하였다. 연구실험실로써 검역해충실험동의 적합성을 확인하기 위해 파밤나방을 이용하여 해충사육, 연구, 밀폐기능을 검증하였다. 해충사육 기능검증에서 한 세대의 파밤나방 완성에 필요한 온도별 생활사는 25°C에서 32.2일이 소요되었으며, 알 부화율은 80%, 유충 용화율은 86.6%, 번데기 우화율은 90%로 조사되었다. 연구기능 검증에서 살포법과 침지법을 이용하여 2종의 살충제(풀룩사메타마이드와 히드라메칠론)에 대한 고도의 유충 감수성을 확인하였다. 밀폐기능 검증에서는 겨울 동안 수행된 검역해충실험동의 유출시험에서 외부에 설치된 성페로몬 트랩에 파밤나방 수컷성충이 포획되지 않아 성충 유출은 없었다. 본 연구결과를 바탕으로 해외해충에 대한 다양한 연구가 검역해충실험동에서 가능할 것으로 판단된다.

The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

A magnetic abrasive finishing process was proposed for improving the surface accuracy of microscale -diameter STS 304 bar used in many applications such as, medical, aerospace, and nuclear industries. Most of the previous research has already explored the conventional finishing technique to improve the accuracy of material in terms of the surface roughness. However, their results are still not good enough for the requirement in the today’s engineering industry. Especially, when the workpiece is a material of microscale-diameter, use of such conventional processes becomes impossible because they entail the application of high pressures that may damage the surface to be finished. Moreover, less control is available over these conventional finishing processes. In this study, an ultra-high-precision magnetic abrasive finishing process was applied to the precision machining of microscale-diameter STS 304 bar and the experimental work are performed with many critical parameters such as, different workpiece revolution speeds, abrasive grain sizes, different finishing temperatures, and pole vibrations. The results showed that in The initial surface roughness of 0.20 μm (Ra) was decreased to 0.025 μm with 0.5 μm of abrasive grain size and pole vibration 12Hz at 40,000 rpm.

스테인레스 스틸에 대한 합성된 폴리우레탄-에폭시 수지의 기계적 특성은 SEM, FT-IR, 인장특성, 그리고 EIS에 의한 특정질량손실량, 입도분석 등에 의해 물성을 측정하였다. 친환경적인 중방식 도료에 관한 관심이 고조됨에 따라 스테인레스 등의 금속에 코팅하는 무용제 도료를 합성하였다. 폴리올, IPDI, 충진제, 실리콘 계면활성제, 촉매 등이 함유된 기존 중방식수지보다 폴리올, MDI, 충진제, 실리콘 계면활성제, 촉매가 함유되어 합성된 중방식수지의 도료가 온도변화에 따른 인장강도가 증가하였고, 전해성이 높은 용액 속에서 저헝력이 크게 측정되었으며, 내구력과 강도가 양호하였다. 견고한 중방 식수지의 기계적 특성은 가교와 부식환경의 차단력이 증가함에 따라 강도가 증가하였다. 결론적으로 중방식의 가교된 미세조직은 방청코팅이 어려운 스테인레스 스틸 같은 금속물질 코팅에도 좋은 실험결과를 보여주었다.

Recently magnesium alloy sheet has been used as a lightweight material in transportation area. Warm forming is a forming method that improves formability and reduces springback. The magnesium alloy sheet has a characteristic that large difference of flow stress increases depending on strain rate at high temperature. These characteristics cause low dimensional accuracy of formed products. In this study, experiments were performed on the 2D-draw bending with respect to the temperature and forming speed in order to investigate the effects of strain rate and temperature. It was found that as the temperature increases, spinrgback of 2D-draw bending decreased and formability of AZ31B increased. Additionally, the effect of the punch speed was investigated. At 250°C, as the punch speed increased, the springback of 2D-draw bending decreased.

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), 40˚C, 60˚C, 80˚C and 100˚C, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of 80˚C > 100˚C > 60˚C > 40˚C > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at 80˚C, 100˚C) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts (80˚C, 100˚C) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

Oxidized PAN (OXI-PAN) fibers were used for the precursors of activated carbon fiber in study. How drying temperature affected the properties of carbon fibers on activating process of carbon fibers was investigated. The specific surface areas of activated carbon fibers have been determined on a series of chemically activated carbons with KOH and NaOH. The experimental data showed variations in specific surface area, iodine and silver adsorptions by the activated carbon fibers. The amount of iodine adsorption increases with increasing specific surface areas in both activation methods. This was because the ionic radius of iodine was smaller than the interior micropore size of activated carbon fibers. Silver adsorbed well in NaOH activated carbon fibers rather than KOH activated carbon fibers in this study.

비정질 SiO2위에서 증착시킨 Si1-xGex합금의 증착온도에 따른 결정성, 미세구조와 조성의 균일성을 X선 회절법과 투과 전자현미겨으로 조사하였고, Si1-xGex/Sio2계면을 고분해능 투과 전자현미경을 이용하여 원자단위로 관찰하였다. Ge의 몰분율을 0.3으로 놓고 증착온도를 300˚C,400˚C,500˚C,600˚C,700˚C로 변화시키며 Si-MBE로 증착된 박막은 , 분석 결과 300˚C에서는 비정질상만이 존재하였고 400˚C에서는 결정상과 비정질상이 공존하고 있었다. 두상은 SiO2위에 함께 증착되었으나 초기 성장에서는 비정질상이 주로 성장되었으며 박막의 두께가 비정질층이 관찰되었다. 600˚C이상에서는 결정상으로만 증착되었다. 증착된 다결정상은 주상성장을 하였다. 증착된 박막의 조성은 중착온도에 관계없이 균일하였으며, Si1-xGex/Sio2계면은 다결정상이나 비정질상에 관계없이 평탄하였다.

This research aim to investigate the qualitative and quantitative performance of concrete deteriorations using Pulse Square Thermography (PST) technique. An experimental test of ten cases was conducted on a concrete slab specimen under different meteorological conditions. The results showed that the absolute contrast between defective area and sound area decreases with the falling of ambient temperature. Besides, the delamination with identical size but placed at a deeper position indicates lower absolute contrast than the shallow delamination.

This paper presents a series of test result in order to study fire resistance capacity of the Near-Surface-Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) plate, which are tensile test of CFRP under various temperature loading, temperature loading test of epoxy and bond test of NSM CFRP to concrete under various temperature loading. From the tests, it was found that NSM retrofit method had high efficiency in strengthening concrete under ordinary temperature. However, the strength of the system was able to be drastically decreased even a little increase of surrounding temperature. Especially, bond capacity begins to disappear when the surrounding temperature approaches the glass transition temperature of epoxy. Therefore, it is necessary to improve the fire resistance capacity of both fiber reinforced polymer reinforcement and epoxy for bonding in order to develop safe fire resistance design of structure

산 함량이 많은 원료로 포도주를 제조할 경우 감산의 한 방법으로 이용하는 CM처리에 있어, CM처리 온도가 포도주의 감산정도와 품질에 미치는 영향을 알아보기 위하여 실험을 수행하였다. 총산 함량에 있어 CM처리 온도가 높을수록 발효 5일째 총산함량은 큰 폭으로 감소하였으나 발효 9일째는 비슷한 것으로 나타났다. CM처리 5일째 포도의 유기산 함량은 CM-에서 사과산 함량이 가장 많이 감소하는 것으로 나타났고, 반면 젖산 함량은 가장 높게 나타났다

넙치 수정란의 발생에 미치는 수온의 영향을 조사하였다. 실험에 사용된 수정란은 실내 사육수조에서 자연산란된 것으로서, 6개의 수온별 실험구(5, 10, 15, 20, 25 및 )에 수용하여 발생과정을 관찰하였다. 수정란은 10, 15, 20 및 에서 부화 가능하였으며, 부화율은 각각 3, 12, 25 및 50%였다. 발생단계별 수온(T, )과 소요 시간(1/t, hour)과의 상관관계식은 다음과 같다. 포배기: 1/t=0.0208T-0.0951 (=0.

To study the shelf-life of cut cabbage kimchi, we examined the several quality characteristics of cabbage kimchi under various storage temperatures and packing materials. The pH of kimchi extracts were decreased to 4.0 in the condition of storage at 8 during 6 days, at 4 during 18days, 0 during 42 days. The increase patterns of the organic acid were reverse to the changes of pH under the all conditions. The contents of reducing sugar were continuously decreased at 8 , but increased gradually at 0 and 4 storage conditions. The contents of vitamine C were decreased at the early storage but increased to optimum ripening stage of pH 4.2-4.4 and after decreased continuously. The total bacterial cell counts of cabbage kimchi were increased suddenly at the early storage and after decreased gradually. And at the higher storage temperature, the more lactic acid bacteria were. On the results of sensory evaluation of cabbage kimchi at marketable shelf-life, sour taste and sour smell were significant under all experimental conditions by Duncan's multiple range test. On the above all results, we concluded that the marketable shelf-life of cut cabbage kimchi were 42 days, 19 days, 6 days at 0, 4, 8 storage condition respectively.