Rolling contact fatigue(RCF) is a major cause of failure that appears in components of rolling contacts. In the recent years, the fatigue propagation and failure have been an important issue in respect of the safe operation and to reduce the noise and vibration of the rolling contact components. The water-contaminated lubrication is known to be one of the significant factors that reduces the lifetime of the rolling contact components. Thus, in this study, the effect of water-contaminated lubrication environment on the rolling contact fatigue was investigated. Bearing life testing was performed in two different lubrication conditions (i.e. normal lubrication environment and water-contaminated lubrication environment). The effect of the debirs on the rolling contact fatigue could be eliminated by establishing the debris filter system. Microscopic features of the rolling contact surfaces were examined using energy dispersive spectrometry and non-contact 3D measurement system. In the case of the water-contaminated lubrication, the increase of surface roughness values up to 17.6% was observed. The oxidation state and pattern of the rolling contact surfaces were very different depending on the lubrication environment. It was also found that the bearing rating life, , was decreased significantly in the watercontaminated lubrication condition. The amount of reduction was about 49.7%.
The physicochemical properties of dry wine produced from domestic kiwifruit according to production year from 2008 to 2012 were studied. pHs of wine were from 4.02(F wine, production year 2009, sterilized) to 4.11(D wine, production year 2012, non-sterilized) and their acidities were lowest in D wine(0.79%) and highest in F wine(1.18%). All the wines have the same soluble solids of 8 °brix and 12% of alcohol, respectively. The reducing sugar was lowest in A wine(production year 2008, non-sterilized) and highest in D wine. The lactic acid was detected as a main organic acid and the free sugar was detected only fructose. As main flavor components, ethyl acetate and 1-pentanol were detected and their sum of 80~90% and a small amount of phenylethyl alcohol which providing rose-like aroma was also detected. The contents of soluble phenolics were highest in D wine(1.07 g/L) and lowest in C wine(0.80 g/L), corresponding to the antioxidant activity was highest found in D wine according to their soluble phenolic contents.
동물들은 항상성 유지를 위해서 지방에 축적된 에너지의 양을 판단하고 섭식량을 조절한다고 알려져 있으나 그 조절 메카니즘은 아직 확실히 알려져있지 않다. 본 연구에서는 노랑초파리로 지방세포에서 섭식조절과 관련된 유전자를 찾기 위해 mRNA의 과발현을 이용한 1차 스크리닝(screening)과 RNAi를 이용한 2차 스크리닝을 수행하여 지방세포에서 발현하는 유전자 purple이 섭식조절과 관련이 있다는 것을 확인하였다. 유전자 purple은 조효소인 tetrahydrobiopterin (BH4)의 생합성에 관여하는 유전자인데, 연구결과 BH4생합성에 관련된 다른 유전자인 Punch와 Sepiapterin Reductase (Sptr) 뿐만 아니라 BH4도 섭식행동을 조절하는데에 관여한다는 것을 밝혀냈다. 흥미로운 사실은 Punch와 purple은 지방에서 발현되어야 하는 반면 Sptr은 뇌에서 발현되어 섭식행동을 조절한다는 사실이다. 추가연구를 통해 BH4가 섭식에 관련된 뉴런인 neuropeptide F (NPF)을 억제하여 섭식억제가 이루어지는 사실을 확인하였다. 본 연구는 새로운 유형의 섭식억제제 개발에 기초적인 정보를 제공할 것으로 보인다.
곤충의 다양한 분류군 중에서 노린재목에 속한 곤충들은 뾰족한 구기를 형태적으로 진화시켜, 이러한 구기를 이용하여 다양한 먹이활동을 한다. 특히, 이러한 구조는 식물체에 직접 구기를 찔러넣어 흡즙하는 형태로 적합하여, 대부분의 노린재목 곤충은 따라서 식물과 밀접한 연관이 있다. 이와같은 이유로, 노린재목 곤충은 산림생태와 아주 깊은 연관이 있으며, 산림성 곤충에 대한 생태적, 종다양성 측면에서 이 분류군의 특성을 이해하는 것이 필수적이다. 이번 발표에서는 노린재목 곤충류 중에서 노린재아목, 매미아목에 속하는 분류군의 다양한 생태적 정보를 소개하고, 특히 종다양성 측면에서 그동안 충남대학교 곤충분류학연구실에서 연구해왔던 결과를 분류군별로 간단히 소개하고 자 한다. 이를 기반으로 향후 산림곤충의 다양한 연구방향과 분야에 도움이 되고자 한다.
In this study, a new designed propeller was applied on 24 ton class squid jigging vessel to reduce of fuel consumption. The selected squid jigging boat was under construction at the shipyard to determine the resistance of the hull through the model experiment. The propeller design was carried out by using the experimental data and ITTC procedures. Sea trials were performed by measuring the speed and the horsepower required by the condition of five power levels of engine load, namely 70%, 80%, 90%, MCR and maximum engine power. The speed and delivered horse power were compared between the conventional propeller and the new design propeller. Delivered horse power by installing the new propeller takes 90% engine load at start-up conducted by decreased 9.06%. The measuring speed is increased up to the 0.6 knots in the low-speed range to high range. This study showed that only the design and installation of a new propeller can improve the propulsion efficiency of the boats; furthermore, reduce fuel costs can be achieved at the same time by improving the increased cruising speed.
This study aims to investigate effects of the length of the buoy and sand bag line on the loss of webfoot octopus pot. A numerical modeling and simulation was carried out to analyze the process that the pot gear affected by wave using the mass spring model. Through the simulation, tensions of sand bag line under various condition were investigated by length of buoy and sand bag line. The drag force and coefficient k of an artificial shell used in the webfoot octopus pot was obtained from an experiment in a circular water channel, and the coefficient k was applied to the simulation. To verify the accuracy of the simulation model, a simple test was conducted into measuring a rope tension of a hanging shell under flow. Then, the test result was compared with the simulation. The lengths of the buoy line in the simulation were 1.12, 1.41, 1.80, 2.23, 2.69, and 3.17 times of water depth. The lengths of sand bag line were 10, 20, 30, and 40 meters, and conditions of water depth were 8, 15, 22 meters. 4 meter height and 8 second period of wave were applied to all simulations. As a results, the tension of the sand bag line was decreased as the buoy and sand bag line were increased. The minimum tension of the sand bag line was appeared in conditions that the length of the buoy line is twice of water depth and the sand bag line length is over 40 meters (except in case of depth 8 meters.).
Ecological restoration is an eco-technology, which heals the nature damaged by human activity by imitating organization and function of the integrate nature and thereby provide an inhabitable space for diverse organisms. Such an ecological restoration has to be carried out by applying restoration plan prepared based on the results of diagnostic evaluation discussed in the diversified respects. This study aims to prepare an ecological restoration plan of the damaged forest ecosystem in Mt. Moodeung National Park. To arrive at the goal, first of all, we diagnosed quality of forest landscape established in Mt. Moodeung National Park based on natural (topography, climate, and distribution of vegetation) and artificial (land use, linear landscape element) factors. In addition, we evaluated the integrity of each zone divided by linear landscape element quantitatively based on geometric property and land use intensity. As the result of analysis, topography of Mt. Moodeung National Park tended to be depended on weathering property of parent rock and vegetation zones were divided to three vegetation zones. Based on land use pattern, deciduous broad-leaved forest, evergreen needle-leaved forest, and mixed forest occupied about 90% of Mt. Moodeung National Park. Mean score of forest landscape quality was shown in 69.86±11.41. As a result, forest landscape elements in Mt. Moodeung National Park were influenced greatly by human activity and the degree was depended on topographic condition. This study suggested the synthetic restoration plan to improve ecological quality of Mt. Moodeung National Park based on the results of diagnostic evaluation.
This study aims to reduce the force exerted to the buoy of the gillnet by wave and current. Five buoy models were selected for experiments and their rope tensions under wave and current action were compared. Five models were EL (ellipsoid), EL-H (ellipsoid-hole), SL (streamlined body), SP (sphere) and CL (cylinder, traditional type). In the first experiment, the Five models were tested without any attachment. In the second experiment, a flagpole was attached to each model. As a result, in the condition without flagpole, the tensions of four models with the exception of the CL were about a half of that of the CL. In the condition with flagpole, the tension of all models was twice larger than that without flagpole. Thus, a new model was suggested to improve the problem, which has a combined body that of a flagpole and a buoy Three new models of CL-L (long and thin cylinder), LF (leaf shape) and LF-F (leaf shape with fin) were designed. Also a cylinder type (CLD) with a flagpole as a control was included in the experiment. As a result, the LF-F had the smallest tension and a half tension of the CLD. Therefore, it is supposed that the flagpole and buoy combined model could reduce the tension on buoy rope and contribute to improve the gillnet loss problem.
대장 내시경 후에 발생한 급성 담낭염은 매우 드문 증례로 알려져 있다. 그러나 담낭염의 위험인자를 가진 환자에서 대장 내시경 후에 복통이 발생했을 경우, 반드시 담낭염을 감별진단해야 한다. 아직까지 정확한 발생 원인에 대해 밝혀진 바는 없으나 대장 내시경 전처치 과정에서 발생한 탈수, 대장 내시경에 의한 대장 점막 손상 등이 보고되었다. 저자들은 대장 내시경후 복통의 원인중 드문 질환인 급성 담낭염을 경험하였기에 문헌고찰과 함께 이를 보고하는 바이다.
목 적 : 대퇴골두 충돌 증후군의 진단과 치료을 위하여 자기공명 3D 재구성 영상과 컴퓨터 단층 촬영 3D 재구성 영상을 비교 평가하여 유용성을 알아보고자 하였다.
대상 및 방법 : 2014년 6월부터 12월까지 본원에서 Hip 자기공명 영상 검사(MRI)와 3D Hip 컴퓨터 단층 촬영(CT)을 동시 시행한 환자 31명 (남: 21명 평균연령: 35세 여: 10명 평균연령: 40.3세)을 대상으로 분석하였다. MR System은 3.0T Magnetom Tim Verio (Siemens Healthcare, Germany)를 사용하여 3D T2 trufi sequence을 시행하였다. 3D T2 trufi의 영상변수는 TR은 5.64msec 이고 TE는 2.48msec 이며, NEX는 1, Slice thickness는 4mm, Matrix: 165×256, FOV: 230×230 이며, Scan time은 2분45초가 소요 되었다. 컴퓨터 단층 촬영의 Protocol은 관전압 120 kVp, 관전류 150 mAs, pitch 1 mm, Increment 0.7 mm, Kernel값은 B60S Sharp을 사용하였다. 영상평가는 정형외과 전문의 1명과 영상의학과 전문의 1명이 MR과 CT modality에서 Hip joint articular transverse ligament의 6 o’clock을 중심으로 superior을 12 o’clock, Labrum의 전면을 3 o’clock, 반대쪽을 9 o’clock로 기술하는 clock face을 재구성 한 후 11 o’clock에서 A.retinacular vessel, B. head neck junction, 12 o’clock A. Epiphyseal line, B. Cam lesion, 1,2,3,4 o’clock의 Cam lesion, Posterior Cam lesion확인 여부를 리커트(Likert scale) 5점 척도로 평가하였다(Independent t-test p<0.05). 평가자간 신뢰도 검증은 Cohen’s weighted Kappa 검증을 이용하여 일치성 검증을 하였다.
결 과 : 영상의 정성적 평가를 위한 리커드 척도 결과 11 o’clock A. retinacular vessel MR 평균 값 3.69±1.0, CT 평균값 2.8±0.78이며 통계적으로 유의하였다(p<0.001). B. head neck junction은 두 평가자간 차이가 없었다(p<0.416). 12 o’clock A. Epiphyseal line MR 평균값 3.54±1.00, CT 평균값 4.5±0.62이었다(p<0.000). B. Cam lesion은 두 평가자간 차이가 없었다(p<0.532). 1,2,3,4 o’clock 의 Cam lesion과 Posterior Cam lesion은 통계적으로 유의하지 않았다(p<0.656, p<0.658). weighted Kappa 검증 결과 11 o’ clock A.retinacular vessel CT K값이 0.663으로 가장 낮은 일치도였으며, 각각의 평가 항목의 일치도 평가결과 매우 높은 결과로 두 평가자간 높은 신뢰도를 보여주었다.
결 론 : 대퇴골두 충돌 증후군의 진단과 관절경을 적용하기 위하여 시행하는 CT 3D-Hip 검사는 MRI 3D clock face 재구성 기법으로 대체 가능하며, 이로 인해 불필요한 환자의 피폭선량을 최소화 할 수 있다. 또한 Cam lesion에 대한 표준화된 영상을 제시함으로써 고관절 수술 시 의료진에게 신뢰할 수 있는 영상을 제공하여 수술 전 효과적인 계획을 수립할 수 있을 것으로 사료된다.
본 연구는 동백나무의 간재적 추정식을 개발하고자 하였다. 제주지역에 자생하고 있는 동백나무 200본을 표준목으로 선정하여 분석 자료로 사용하였다. 재적모델 개발을 위해 80% 자료와 모델 타당성 검정(Validation)을 위해 20% 자료를 무작위로(Randomly) 구분하여 분석하였고, 본 연구에서 제시된 최종모형의 추정된 계수는 100% 자료를 이용하였다. 동백나무에 대한 재적 모델의 적합성 검정은 결정계수(R2), 추정치의 오차(RMSE), 평균편의(MD), 절대평균편의(AMD)와 직경급별 평균편의(MD), 변동계수(CV%)를 비교 분석하였다. 본 연구 결과, 결정계수는 0.7571에서 0.9381로 나타났으며, V=aDbHc에서 결정계수가 가장 높은 것으로 나타났다. 추정치의 오차는 0.0326으로 V=aD2H에서 가장 높았으며, 반면에 0.0258로 V=aDbHc에서 가장 낮았다. 평균편의는 V=a+bD2H에서 0에 값으로 나타났으며, V=aDbHc에서 0.0012로 나타났다. 절대평균편의는 V=D2/(a+b/H)에서 0.0186으로 가장 낮았고, 0.0223으로 V=aD2H에서 가장 높게 나타났다. 변동계수는 V=aDbHc에서 30.4348로 가장 적합한 계수로 나타났다. 5개의 모델식 중 최적의 식은 V=aDbHc에서 나타났으며 V=aD2H에서 적합성이 가장 낮은 것으로 나타났다.
Membrane distillation (MD) is a hydrid membrane process using the temperature difference as a driving force. In order to enhance the performance (flux) of the MD process, various membrane structures (asymmetric or bi-composite) and materials (PP, PVDF or PTFE) have been suggested. In this study, the support layer of the commercial PTFE/PP bi-composite membrane is modifed by forming the macro punctures in it. The size and location of macro punctures were varied according to the designed support layer porosities (50, 60, 70 and 80 %). The modified membrane test was conducted by using the DCMD configuration. The flux of a modified membranewas enhanced up to 27 % compared with that of pristine membrane when the size of the macro puncture and overall porosity of the support layer were larger than 20 mm2 and 60 %, respectively.
This study was begun with the object of actively reflection the rapid technological advancements of the electronical control and mechanical control industries to sewage disposal methods. Or focuses on applying a flow control method that utilizes inverters and automatic valves to sewage treatment process systems.This study proposes that sewage treatment process systems architects must acquire a certain degree of technical skills in the areas of electrical and mechanical controls in order to raise the standard of completeness of sewage treatment process systems. And further emphasizes that there is required continuous research on automatics valves that are used in sewage treatment.
본 연구에서는 역삼투막공정을 이용하여 수용액 중 저준위 방사성이온인 세슘과 요오드 이온을 제거하는 실험을 수행하였다. 국내에서 생산되는 역삼투막모듈 두 가지와 그리고 폐모듈 세정한 후 세슘과 요오드 이온에 대한 제거성능을 비 교하였다. 공급수의 농도와 압력을 달리하여 실험을 진행한 결과, 세 가지 모듈 모두 세슘에 비해 요오드의 제염계수가 높은 것을 알 수 있었으며, 특히, 세정한 모듈은 요오드에 대한 제염계수가 1140으로 확인되었다. 대체적으로 실험조건이 고압일 때보다 저압일 때 제염성능이 좋은 것으로 나타났으며 이는 저압조건에 가까운 압력을 갖는 수도수에 직접 모듈을 설치할 경우에도 사용이 가능하리라 판단되었다. 또한 EDTA와 SBS, NaOH, 마이크로버블 등을 사용하여 세정한 막의 제염성능이 세정 전의 제염성능보다 높아졌으며 저압, 저농도 조건에서 요오드에 대한 회수율이 세정 후에 6.3% 증가한 결과를 얻었다.