This study aimed to develop an optimal greenhouse model for strawberry seedling during the summer high-temperature period based on the results of field surveys. We conducted a survey on the structure types of 46 strawberry seedling farms nationwide, including width, ridge height, eaves height, ventilation method, seedling bed width, and spacing. Based on the survey results, we derived the optimal greenhouse model by considering various factors. The greenhouse width was set at 14 meters to maximize the efficiency of seedling beds and overall space. The height was determined at 2 meters, taking into account ventilation during the summer season. To reduce stress on the supporting structure due to snow loads, we established a reinforcement installation angle of 50 degrees. We analyzed two different models that use support beams with dimensions of φ48.1×2.1t and φ59.9×3.2t, respectively, to ensure structural safety against meteorological disasters, considering regional design wind speeds and snow accumulation. We utilized these developed greenhouse model to conduct strawberry seedling experiments, resulting in a high survival rate of average 93.2%. These findings confirm the usefulness of the strawberry seedling greenhouse in improving the seedling environment and enhancing overall efficiency.

This paper proposes a method to evaluate the structural safety of a large wide-width greenhouse structure against wind load caused by a typhoon through a fluid structure interaction analysis technique. The conventional method consisted of roughly estimating the wind load based on the relevant laws and regulations, and determining safety through structural analysis. However, since the wind load changes nonlinearly according to the wind speed distribution and wind direction around the greenhouse and the external shape of the structure, there are many uncertainties in the existing structural safety evaluation method, and it is difficult to accurately determine the design margin. In this study, a systematic method was developed to accurately calculate the wind load acting on a greenhouse structure and evaluate structural safety by considering the characteristics of wind through a fluid structure interaction analysis using coupled computational fluid dynamics and computational structural mechanics. Using the proposed method, it is possible to significantly reduce the manufacturing cost because it is possible to obtain an optimal design that reduces the over-conservative design margin while securing the structural strength of the greenhouse.

In this study, a high speed planing boat with 7.2 meters in length is developed as the beam larger about 10% by comparing with the general planing boat. The design speed of a boat is 30 knots (about 15.4 m/s) by using 150 hp outboard engine and the main material is FRP. The resistance performance related to the free running attitude as trim and sinkage is discussed and the wave patterns are observed to clear the relationship between the performance and wave characteristics by model test. The turning circle is estimated by Lewandowski´s equation. The results show that not only the wave pattern but also the free running attitude of the boat have the strong influence on a resistance performance. The boat needs smaller engine power and has more stable running attitude because of large sinkage and small variation of trim due to the large area for the lift force and light weight.

One simple way of increasing the heat transfer for a fin-and-tube heat exchanger is to increase the fin surface area. In this study, a series of tests were conducted on wide slit fin heat exchangers having an increased fin area (Pl/Pt = 0.87), and the results were compared with those of standard slit fin heat exchangers (Pl/Pt = 0.6). Thermal performances of wide silt-finned samples were superior to those of standard slit fin samples. For one row configuration, the j factor of the wide slit fin sample was 11% larger, and the f factor was 33 % smaller than those of the standard slit fin sample. The difference decreased as the number of tube row increased, although wide slit fin sample always yielded superior performance, The reason was attributed to the many narrower slits formed on the wide fin sample. Furthermore, the effect of fin pitch on j and f factor was not significant, and j factor decreased with the increase of the number of tube row.

The EMI shield material with narrow width has some deficiencies in shielding capability and this deficiencies are caused by the inconsistent relationship between the inductance and temperature after heat treatment. This study is performed to develop a nano crystal magnetization heat treatment process technology and design a EMI shielding material with wide width up to 350mm. As a result, the performance of the developed wide EMI shield material satisfies all the objects of this study such as the inductance, thickness, permeability, ribbon productivity, lamination productivity. Also, we find that this wide EMI shield material can be used effectively for the EMI shield room, large medical equipment and so on.

포스트텐션 콘크리트 포장(PTCP: Post-Tensioned Concrete Pavement)을 한방향 4차로로 타설 시 2 차로 선타설 이후 나머지 2차로를 후타설하게 된다. 선타설된 슬래브는 후타설을 수행하기까지 긴장력 도입과 건조수축에 의한 변형이 발생하게 되며, 선타설 슬래브의 변형이 일정정도 진행된 이후 후타설 슬래브가 타설된다. 후타설 슬래브는 긴장력과 건조수축에 의한 변형이 발생한 선타설 슬래브와 맞추어 시공 되기 때문에 후타설 슬래브가 긴장력과 건조수축에 의해 슬래브가 수축하게 되면 타이바로 연결된 선타설 슬래브와 후타설 슬래브는 상호간의 수축차로 인해 추가적인 인장·압축응력이 발생하게 된다. 그림 1(a) 는 선타설 이후 약 21일 후 후타설 슬래브를 타설하였을 경우에 대하여 건조수축과 긴장력을 도입하였을 경우의 응력분포와 변형을 나타낸 것으로 긴장력이 도입되었음에도 일정부분에서는 인장응력이 발생하는 것을 알 수 있다. 그림 1(b)는 철근깊이에서의 종방향길이에 따른 종방향응력을 나타낸 것으로 타이바와 콘크리트 접촉부에는 매우 큰 인장응력이 발생하여 슬래브의 파손 가능성이 큰 것으로 나타났다. 타이바에 의한 긴장응력 억제를 완화하기 위하여 본 연구에서는 두 가지 대안에 대하여 분석하였다. 첫 번째 방안으로는 타이바의 유동공간을 확보하여 긴장과 건조수축 시 타이바와 콘크리트 접촉부의 응력을 완화하는 방법으로 유동공간을 크게 할수록 접촉부에서의 인장응력은 작게 발생하지만 타이바에 의한 손실이 여전히 큰 것으로 나타났다. 두 번째 방법은 긴장부에서의 타이바 제거를 통해 타이바에서의 변형량이 작아지도록 하는 방법으로 120m PTCP에서 양단 20m 부분의 타이바를 제거하는 방안이다. 이 방안 또한 슬래브에 발생하는 응력은 작아지지만 여전히 슬래브의 파손이 우려되는 응력이 발생하는 것으로 나타났다. PTCP를 포함하여 다른 포장형식 또한 한방향 4차로 포장의 경우 타설 시기 차이로 인한 건조수축 등의 거동으로 인해 타이바에 따른 응력이 발생할 수 있으며 이에 대한 추가적인 연구가 필요하다.

Background : This study was conducted to develop sustainable and safe ginseng cultivation facilities to cope with climate change and to save labor due to the decrease of labor force in rural areas. Methods and Results : In 2017, we designed the wide-shading facility which was unmanned and labor saving to cope with climate warming and decreasing labor force in farming area for stable and sustainable production of ginseng. The developed model is called model Ⅰ(Slope-shading facility, Gyeongsangbuk-do ARES), model Ⅱ (Slope-shading facility, Gyeonggi-do ARES) and Model Ⅲ (Roof-type shading facility, RDA, NIHHS, Department of Herbal Crop Research). The tested varieties were stem-violet variant, and the transplanting was done by using the 2-years-old seedlings on April 3, 2017 and the planting density was 90 plant/1.62㎡. A thermometer, a light meter, and a rain gauge were installed in the center of the facility on April 13, 2017 to measure the micro-weather in the facility. Micro-weather observations were made from April 14 to October 10, measuring temperature, humidity, light intensity, soil moisture content, water leakage, and wind speed. Surveys were carried out on June 20 and September 29, respectively. The maximum temperature in the facility was 2 to 3℃ lower than the outside, but the relative humidity was 2 - 3% higher in the facility than in the outside. Soil moisture did not show a clear trend among the models. The light transmittance was 5 - 10% and it was the highest in model I, where the height of the shading facility was the highest. Rain leakage was 10 - 36%, the most in model Ⅱ. The amount of leaks increased with the amount of precipitation per hour. In all models, ginseng stem and leaf were damaged due to excessive water leakage. On July 10, stem and leaf were grown well only in wide-shading facility where leakage was adequately blocked with double-sided film. The average wind speed was less than 1.6 m/s during the survey period. The maximum wind speed was 8.8 m/s or less, which did not affect the deformation of the wide-shading facility. In all models, there was no difference in growth of aboveground part and root. Conclusion : As a result, in order to grow ginseng continuously and stably using wide-shading facilities, it is considered that the amount of leakage should be minimized by using material that can prevent leakage in cope with rainfall or heavy rain rather than wind-resistance.

Background : Rural communities were facing labor difficulties due to old age and increasing number of women in the labor force. These factors have caused decrease in effectivity and productivity of ginseng production. Also, due to repetitive ginseng cultivation, salt accumulation in soil becomes more evident. When too much salt is present, ginseng plants appeared to have red colored roots and this caused the fall down of marketability of ginseng. In this study, we tested the use of wide shade facilities to enhance the growth traits of ginseng. Wide shade facilities can also reduce the working expenses of transfer cultivation and replacement by around 1,500,000 won/10a. In addition, this might also reduce the consequences of continuous cropping, thus obtaining a stable and safe field. Methods and Results : We set up 3 kind of facility as wide shade, supply type wide shade and conventional shade in Ginseng & Medicinal Plant Research Institute, Chungnam Agricultural Research & Extension Services. Wide shade facility used three different types of shade material, black, red, and blue films. Supply type wide shade facility and conventional shade used polyetylene (PE4 + PE2) film. The planting size were 10 ㎝ × 18 ㎝ (9 × 10 plants), planting number: 90 plants/3.2㎡ in wide shade (include supply type wide shade) and 10 ㎝ × 18 ㎝ (8 × 10 plants), planting number: 80 plants/3.2㎡ in conventional shade. Our results showed that temperature was lower (-0.5℃) in wide shade facility than in supply type and conventional shade. conventional shade was lower (-0.5℃) or similar than in supply type shade. We investigated growth of Korean ginseng 3-years-old root for each facility. Results showed that total growth such as root weight, length was higher in supply type facility than in wide shade and conventional shade facility. Root rot was lower in supply type facility. Conclusion : Wide shade facilities was shown in low temperature than in supply type and conventional shade. Supply type was good for root growth and root rot disease. These finding could be used for place fixed cultivation for ginseng using wide shade facility.

Background : This study researches on the microclimate, photosynthesis and growth characteristics for the development of shading materials proper for the wide and inclined ginseng cultivation facility which can respond to climate change and save labor. Methods and Results : The wide shading facilities were installed on the area of 1,000 ㎡ in 2014 and 4 facilities were installed on the test ginseng cultivation area. On Mar. 29, 2017, 2 blue shading nets [with the sun blocking rate of 85% (200 g/㎡) and 90% (220 g/㎡)] were installed each for 4 facilities. On June 26, 2017, the aluminum screen and black shading net (with the sun blocking rate of 40% each) were installed during the period of high temperature (30℃ or higher) for each facility. The maximum light intensity under the shading facility was high with blue shading net 85% and PE black shading net 40%, or blue shading net 85% and aluminum screen 40%, higher than other treatments. They were higher by 4.8 - 7.3%, 5.3 - 7.8% each in July and August. Among the coating materials for reducing the high temperature, the aluminum screen coating had less water leakage in early July, late July, mid-August and late August when the precipitation was more than 100 ㎜. The death of the aerial part of ginseng occurred less until October. The growth of the aerial part of 4-year ginseng was better in blue shading net 85% and PE black shading net 40%, blue shading net 85% and aluminum screen 40% or blue shading net 90% and PE black shading net 40% than in blue shading net 90% and aluminum screen 40% The photosynthesis rate was the highest in June with 3.67 μmol CO2/㎡/s under the blue shading net 90% and aluminum screen 40% and with 3.55 μmol CO2/㎡/s under blue shading net 85% and PE black shading net 40% for K-1. As for the land races ginseng, it was the highest with 3.55 μmol CO2/㎡/s under the blue shading net 85% and PE black shading net 40%. For the growth of the underground part of the 4-year ginseng, the blue shading net 85% + PE black shading net 40% or the blue shading net 85% + aluminum screen 40% was the best with respect to the growth of the ground part of the ginseng such as the length of root, the length of main root, diameter of root and weight of root than other treatment. Conclusion : Best coating materials for the wide shading facilities are the blue shading net 85% and aluminum screen 40%.

아스팔트 콘크리트 궤도(ACT)의 변형을 최소화하고 구조적 안전성을 확보하기 위해서는, 열차 하중을 분산 및 저감시킬 수 있고 아스팔트 도상의 노출을 줄일 수 있는 광폭 형태의 콘크리트 침목이 필요하다. 본 연구에서는 형상 설계를 통해 아스팔트 콘크리트 궤도용 광폭 PSC침목을 개발하였으며, 유한요소해석을 통해 레일 좌면부 및 침목 중앙부에 대한 구조 안전성을 검토하였다. 또한 아스팔트 콘크리트 궤도용 광폭 PSC침목의 설계 적합성을 검증하기 위하여, EN 13230-2에 의거 침목 주요 위치별로 정적 휨 강도 시험, 동적 휨 강도 시험 및 피로 시험을 수행하였다. 성능 시험 결과, 아스팔트 콘크리트 궤도용 광폭 PSC침목은 균열 하중, 파괴 하중, 및 균열 확대 여부 등 유럽 표준에서 요구되는 성능 기준을 모두 충족하였다.

Background : The study is designed to establish the standard of wide-shading facilities for the energy-saving and labor-free system in response to the shortage of manpower in rural areas by introducing North American style Ginseng cultivation facility. Methods and Results : This study was carried out at the Income & Resources Research Institute, Gyeonggi Agricultural Research & Extension Services, located in Shinseo-myeon, Yeoncheon-gun, Gyeonggi-do in 2015 in order to establish the standards for wide-shading facilities for energy-saving and labor-free system in response to Korea's climate and lack of manpower in rural area. The shading materials used were blue shading net made with coolaroo fabric, aluminum screen (shading rate 40%) and black shading net (shading rate 40%). As for the installation of additional shading materials, the blue shading nets (200 g/㎡ and 220 g/㎡) were installed on Apr. 1, and then the aluminum screens and black shading net were installed on Jun. 1 when it was hot (with the outside temperature of 30℃ or above. To determine the suitability of the shading materials, the growth environment in the shading facilities such as temperature and humidity, light quantity, and water leakage were measured. The growth was investigated for the above-ground part and underground part of the plants in accordance with the research standards of the Rural Development Administration (RDA). As for the temperature in the shading facilities, the temperature in the aluminum screen was higher than that of the black shading net, and the humidity in the aluminum screen was lower than that of the black shading net. The light intensity and transmittance were higher in the aluminum screen than those in the black shading net. The water leakage was absent on aluminum screen, but it was 8.1 - 11.5% in the black shading net. Although the growth of shoots above the ground showed no difference between shading materials, the growth of the shoot underground was better in the black shading net than in the aluminum screen in high temperature. In particular, the weight of Ginseng root increased by 19.1% in the black light shade compared to that of the aluminum screen. Conclusion : The results of the study showed that the combination of shading materials suitable for wide shading facilities in Korea in response to the lack of manpower in rural areas due to climate change and rural aging is the combination of "blue shading net + black shading net".