The microstructure, hardness, and wear behaviors of a High Velocity Oxygen Fuel(HVOF) sprayed WC-CoFe coating are comparatively investigated before and after laser heat treatments of the coating surface. During the spraying, the binder metal is melted and a small portion of WC is decomposed to W2C. A porous coating is formed by evolution of carbon oxide gases formed by the reaction of the free carbon and the sprayed oxygen gas. The laser heat treatment eliminates the porosity and provides a more densified microstructure. After laser heat treatment, the porosity in the coating layer decreases from 1.7% to 1.2 and the coating thickness decreases from 150 μm to 100 μm. The surface hardness increases from 1440 Hv to 1117 Hv. In the wear test, the friction coefficient of coating decreases from 0.45 to 0.32 and the wear resistance is improved by the laser heat treatment. The improvement is likely due to the formation of oxide tribofilms.

Recycled aggregate is a solution to reduce construction waste and to be environmentally friendly, but concrete using it has various disadvantages in terms of structure. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. Eighteen specimens were constructed to confirm the compressive behavior of RCFT (Recylced Concrete Filled Tube) columns, which can be applied to real buildings by making high strength concrete with recycled aggregate. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. A total of three recycled aggregate concrete preformulations were used to find the optimal mixing ratio and the compressive behavior was analyzed through the load - displacement curves of RCFT columns.

As buildings are becoming larger, demand for large-scale composite columns for heavy load is increasing. Welded built-up CFT column (ACT Column I) previously developed by authors of this study is structurally stable and economical. Characteristic of welded built-up CFT column is that there is a limitation of cross-sectional size and application of external diaphragm connection to ensure continuity of rib. Then, composite mega column (ACT Column II) was developed to improve limit of cross-sectional size. Composite mega column has a closed cross section like welded built-up CFT column, but thick plate is inserted between cold-formed steel to expand cross section size. However, when external diaphragm connection is applied to composite mega column, amount of steel is increased greatly and interference with finishing material occurs. In this study, internal diaphragm connection is applied through characteristic of composite mega column to which beam flange or stiffener can be attached to plate. In order to analyze this, simple tensile experiment of composite mega column connection with T-shaped stiffener was performed.

This study investigated the effect of the grinding media of a ball mill under various conditions on the raw material of copper powder during the milling process with a simulation of the discrete element method. Using the simulation of the three-dimensional motion of the grinding media in the stirred ball mill, we researched the grinding mechanism to calculate the force, kinetic energy, and medium velocity of the grinding media. The grinding behavior of the copper powder was investigated by scanning electron microscopy. We found that the particle size increased with an increasing rotation speed and milling time, and the particle morphology of the copper powder became more of a plate type. Nevertheless, the particle morphology slightly depended on the different grinding media of the ball mill. Moreover, the simulation results showed that rotation speed and ball size increased with the force and energy.

As buildings are becoming larger, demand for mega-sized composite columns (over 1-meter diameter) is increased. We have developed and commercialized welded built-up CFT column (ACT Column I) since 2005 which are structurally stable and economical using cold-formed steel with rib. However, there has a limit in size of cross section (618˟618mm) by a fabrication facilities. And due to characteristics of closed cross section, there has a limit to construction of connection of moment frame. Composite mega column (ACT Column II) has same concept of forming closed cross section. But in order to enlarge cross sectional size, thick plate is inserted between cold-formed steels. Since composite mega column can control thickness and width of thick plate, steel or composite beams can be directly attached to the connection. In this study, we propose strength formula of composite mega column to beam connections with T-shaped stiffener as internal diaphragm and verified through finite element analysis and simple tensile experiment.

국내 개발품종의 해외수출 기반을 조성하기 위해서 산림버섯연구센터 개발품종의 일본 및 미얀마 지역 적 합성 검토를 위한 시험포를 조성·운영하고 있다. 2016년부터 일본 키노쿠스사의 재배사를 이용하여 산조 710호를 포함한 3개 품종의 현저적용 가능성을 확인하고 있으며, 미얀마 샨고원 지역의 표고시험포에서 산림버섯연구센터 개발품종인 산조701 호의 적응성 시험을 진행하고 있으며, 이를 기반으로 미얀마 삔라 웅 지역의 20만평 고산지대에 조성중인 표고생산단지에서 국내품종의 재배 및 미얀마 및 일본으로 생산된 버섯의 판매가 이루어질 예정이다. 이를 통해 대한민국의 국제적 위상을 올리며 국산 표고품종의 해외수출 기반을 마련하는 계기가 되었다.

국산 산림버섯의 수요확대와 재배기술 요구에 대응하여 산림조합중앙회 산림버섯연구센터에서는 표고버섯의 활성화와 안정적 저변확대를 위해 수준별 교육으로 표고버섯의 초급교육 및 전문가양성교육을 진행 하고 있으며, 2017년 국산 산림버섯 품목의 개발 및 보급확대를 위해 신규로 목이버섯 재배기술교육을 실시하고 있다. 표고버섯 초급교육은 매월 1회, 1일 8시간 교육을 진행하고 있으며, 표고버섯 전문가양성교육은 년 1회, 1년 동안 1주씩 5차에 걸쳐 총 5주간 실시하고 있고, 목이버섯 교육은 격월 1회, 1일 5시간 교육으로 진행하고 있다. 표고버섯 초급교육은 귀산촌인, 재배희망자를 대상으로 이론교육 및 현장견학으로 2011년부터 시행하여 2011년(302명), 2012년(807명), 2013년(1,077명), 2014년(1,110명), 2015년(1,116명), 2016년(869명), 2017년 현재 5기(336명) 진행하였다. 표고버섯 전문가양성교육은 이론 및 실습, 선도임가 현 장견학 과정으로 2011년부터 시행하여 매년 1기수씩 수료하였으며, 2016년까지 6기 교육생을 배출하였으 며, 2017년 현재 7기 교육과정을 진행중이다. 목이버섯 교육은 귀산촌인, 재배희망자를 대상으로 이론교육 및 현장견학으로 2017년 1월 1기 시범교육을 시작하여 현재까지 3기(131명) 진행하였다. 이외에도 순회교 육, 상설교육, 현지지도 등 매년 약 3,000여명 지도 및 교육을 수행하고 있다.

표고 톱밥재배용 우량 품종을 육성하기 위해 생산성 높고 품질이 우수한 산조701호와 수집균주 FMRI1132 를 모균주로 선발하였다. 이들 모균주들로부터 수집된 담자포자를 발아시켜 모균주별로 20개씩 단핵균주를 선발하여 400개 교배조합을 실시하였다. 이들 중 60개 교배균주를 선발하고 톱밥재배 자실체 특성검정을 통해 생산성 및 형태적 특성이 우수한 균주를 최종 선발하여 산조710호라 명명하였다. 산조710호의 균사생장 적온은 25°C, 버섯 발생온도 범위는 12~25°C로 중고온성이며, 버섯발생 및 생육은 18~23°C 내외에서 가장 좋았다. 갓형태는 평반구형이며 버섯의 육질이 단단하고 모균주인 산조701호에 비해 배양숙성 기간이 30일 이상 짧아 버섯발생이 빠른 품종으로 판단되었다. 갓두께는 20.3mm로 두꺼우며 갓직경과 대길 이를 비교한 갓/대길이 비율은 2.3으로 갓에 비해 대가 짧은 형태적으로 우수한 특성을 보였다. 대길이는 30.4mm, 대굵기 12.9mm, 개체중이 20.1g으로 비교적 중형 또는 중소형의 자실체 특성을 나타내었다.

봄철 건조기후로 인해 봄철 표고버섯 생산량이 감소하므로서 표고 원목재배임가에서는 어려움을 호소하고 있다. 이에 표고 원목재배에서 봄철 건조시기에 표고버섯의 생산성을 높이기 위한 시험을 실시하였다. 표고 원목재배 재배하우스 내에서 2014년 ‘산조502호’ 품종을 접종하여 배양중인 버섯목에 대하여 건표고용 봄버섯이 발생되는 시기인 2016년 3월 중순에서 4월초까지 비닐피복(0.05mm) 시험구와 비닐피복하지 않은 시험 구(각 처리구별 22본)를 처리하여 자실체 발생량, 버섯품질, 온습도 등을 조사하였다. 피복내외의 온습도 환경 조사를 위해 표고 재배사 내에 피복 처리구와 무피복 처리구구에 온습도기록기를 설치하고 2016년 봄철에 접어들어 처음으로 표고가 발이 되기 시작한 3월 21일부터 버섯수확을 마치고 피복을 제거한 4월 12일까 지 온도(최고, 최저)와 습도(최고, 최저)를 시험구별로 분석한 결과, 최고온도는 무피복 처리구가 0.7°C 높은 반면 최저온도는 피복처리구가 1.2°C가 높아 피복효과가 나타났다. 습도를 보면 최고습도는 피복 처리구가 2.6% 높아 많은 차이를 보이지 않았으나 최저습도의 경우는 피복처리구가 10.3% 높아 버섯 생산량과 버섯품 질을 결정하는 결정적인 요인으로 작용하는 것으로 보였다. 처리구별 버섯 발생량 및 발생 수량을 살펴보면, 각 시험구에서 처리 8일후(3월 29일)부터 버섯이 발생되기 시작하여 4월 10일에 모든 버섯 수확이 완료되었다. 총 버섯수확량은 피복 처리구에서 11,145g의 버섯이 수확되어 무피복 처리구에서 발생한 5,330g에 비하여 두배 이상의 월등히 많은 양의 버섯이 수확되었을 뿐 아니라 버섯 발생 개수도 무피복 처리구가 208개에 비해 348개로 많이 발생되었으며 개체중량 또한 25.6g에 비하여 32.0g으로 6.4g 중량이 높게 나타났다.

전세계 해상 조난 및 안전제도의 시행에 따라 GMDSS 통신설비의 운용과 이에 대한 정확안 활용이 요구된다. 본 연구의 목적은 GMDSS 시뮬레이션 교육이 해상무선통신사의 해상용 통신기기 및 운용에 관한 이해력을 평가하고자 하였다. 이러한 연구의 목적을 달성하기 위해 A1해역에서 발생한 조난신호에 대한 처리능력을 시뮬레이션을 이용하여 전송하는 단일 시나리오는 적용하여 남 녀 10명에게 상활을 이해하고 처리하는 능력을 평가하였다. 평가결과 시뮬레이션을 이용한 시나리오 전략 교수는 연구대상자의 조난상황 처리능력을 향상시키고 해상통신기기 및 활용에 대한 이해력을 높이는 것으로 평가되었다.

WC-CrC-Ni coatings were prepared by nine processes of the Taguchi program with three levels for the four spray parameters: spray distance, flow rates of hydrogen and oxygen, and powder feed rate. The optimal coating process (OCP) was oxygen flow rate of 38 FMR, hydrogen flow rate of 53 FMR, powder feed rate of 25 g/min, and spray distance of 7 inches. Hardness of 1150 Hv and porosity of 1.2 %, were obtained by OCP; these are better results compared with the highest 1033 Hv and the lowest 1.5% porosity obtained by nine processes of the Taguchi program. Friction coefficient of the WC-CrC-Ni coating decreased from 0.36 ± 0.07 at 25 oC to 0.23 ± 0.07 at 450 oC. These values were smaller than those of the EHC (electrolytic hard chrome) plating at both temperatures due to lubrication from the oxide debris. The wear trace and wear depth of the coating are smaller than those of the EHC at both temperatures. Pitting was not found in the WC-CrC-Ni coating sample, while it did appear in the EHC sample.

This study was performed to propose the sewer defect scoring, and grading protocols for sewer condition assessment. For this, sewer defect scoring methods were comparatively analyzed and reviewed for four international condition assessment protocols, which are established based on WRc manual. As a result, we proposed a new protocol for sewer condition assessment, in which characteristics of sewer pipes are considered by segment. In reference to the PIM-3, the extent of ground subsidence was adopted to be of importance, and renewal scores increased in accordance with weighting of defects causing structural backfill materials. Also, defect grades of ‘Hole’ were extended to 5 levels of the grading, and ‘Surface Damage’ was excluded in defect assessment. The addition of ‘Buckling’ resulted in reduction of weights in ‘Surface Damage’ and ‘Lining Defects’.

Sewer condition assessment involves the determination of defective points and status of aged sewers by a CCTV inspection according to the standard manual. Therefore, it is important to establish a reliable and effective standard manual for identifying the sewer defect. In this study, analytic reviews of the CCTV inspection manuals of the UK, New Zealand, Canada and South Korea were performed in order to compare the defect codes and the protocols of condition assessment. Through this, we also established the standardized method for defect code and revised the calculation method of assigning the condition grade. Analyses of the types and frequencies of sewer defects that obtained by CCTV inspection of 7000 case results, showed that the joint defect and lateral defect were the most frequent defects that occurred in Korea. Some defect codes are found to be modified because those did not occur at all. This study includes a proposed new sewer defect codes based on sewer characteristics.

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

This study was conducted to develop a handy earth auger for use in sloppy and rugged forest terrains in order to reduce labor cost which comprises a major part of the production costs in forest afforestation projects. The first prototype is developed consist of two parts, the soil-digging screw and the battery power source. The specifications of the first prototype screw are: length of 170㎜, a top diameter of 60㎜, bottom diameter of 47㎜, 23° angle for each helix, and a 50㎜ awl-head tip. The use of a single line of screw was selected for reduced weight. In addition, a power source of rotary DC Motor(WD-6G2425, WONILL, Korea) with a maximum torque of 30㎏ f-㎝, rotation of 20-30rpm, K6G30C decelerator with a reduction ratio of 30:1 which could be used with no load for 48 was operated. In consideration of its weight, a lithium battery was utilized in line with the goal of developing a lightweight auger. In order to evaluate the performance of the first prototype, test sites were selected as 6 areas. The rotational force was found to be highest in area A(Solid area), followed by areas F(Mounted slope 40° area) and E(Mounted slope 30° area). It was also observed that in general, the rotational force increased along with the increase in soil depth with the maximum rotational force recorded at 10㎝.

In this study, the RDII predictions were compared using two methodologies, i.e., the RTK-based and regression methods. Long-term (1/1/2011~12/31/2011) monitoring data, which consists of 10-min interval streamflow and the amount of precipitation, were collected at the domestic study area (1.36 km2 located in H county), and used for the construction of the RDII prediction models. The RTK method employs super position of tri-triangles, and each triangle (called, unit hydrograph) is defined by three parameters (i.e., R, T and K) determined/optimized using Genetic Algorithm (GA). In regression method, the MovingAverage (MA) filtering was used for data processing. Accuracies of RDII predictions from these two approaches were evaluated by comparing the root mean square error (RMSE) values from each model, in which the values were calculated to 320.613 (RTK method) and 420.653 (regression method), respectively. As a results, the RTK method was found to be more suitable for RDII prediction during extreme rainfall event, than the regression method.

우리나라에서 개미가 종자를 분산시키는 반기생 한해살이풀 며느리밥풀속 식물종의 서식지, 전파체 특성과 관련 개미를 밝히고자, 2012년 5월부터 2015년 11월까지 며느리밥풀속 3종의 서식지 특성, 열매 수집, 전파체 특성 및 급여시험을 실시하였다. 며느리밥풀속 서식지는 약산성의 토양층이 비교적 얕은 남향사면 수관층이 열린 숲 가장자리 였다. 공통적으로 출현한 식물종은 신갈나무를 포함한 4수종과 대사초를 포함한 4종의 초본식물이었다. 이들 식물종들 이 며느리밥풀속의 숙주식물일 가능성이 높다고 사료된다. 며느리밥풀속 전파체의 모양은 타원형의 종자 한 쪽에 백색의 지방체가 모자처럼 붙어있는 형태였다. 전파체 중량은 새며느리밥풀이 10.6mg으로 가장 무거웠고, 알며느리밥 풀이 8.0mg, 꽃며느리밥풀 7.2mg의 순으로 나타났다. 지방체 중량은 알며느리밥풀이 1.2mg으로 가장 무거웠고, 새며 느리밥풀 1.0mg의 순이였으며, 꽃며느리밥풀이 0.8mg으로 가장 가벼웠다. 며느리밥풀속 서식지에서 전파체를 활발히 물어가는 개미는 두마디개미아과(Myrmicinae)에 속하는 3속 4종의 몸집이 작은 개미들로 코토쿠뿔개미, 항아리뿔개미, 가시방패개미와 일본장다리개미로 확인되었다. 반기생 한해살이풀이며 개미가 종자를 산포하는 며느리밥풀속 식물체 들은 개체의 생육상태에 따라서 변이가 크며, 환경조건의 변화에 민감하므로 많은 연구가 필요하다고 사료된다.

딸기잎선충(Aphelenchoides fragariae)에 감염된 딸기(Fragaria x ananassa Duch.) cv. 장희에서 부위별로 감염 증상을 조사하였다. 감염주 전체의 딸기잎선충 밀도는 최고 23,293마리였고 감염된 딸기주는 정상포기에 비하여 속잎이 위축되게 나타났다. 특히 감염주의 꽃대 길이는 정상주에 비해 26%로 현저히 짧았으며, 심하게 감염된 포기로부터 꽃대에는 기형과가 형성되었다. 크라운, 잎자루, 잎, 꽃대, 꽃받침, 열매 등 부위별 딸기잎선충의 밀도를 조사한 결과 꽃받침에서 가장 높은 밀도(403마리/g)를 나타냈다.