• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1907-1910
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• 2003

Miniaturized machine tool can be used to produce 3D features based on CNC and PC-NC technology in the micro/meso scale. Wide applications of CNC technology are developed and there are lots of know-hows in the cutting process and their CNC application. It helps micro/meso scale structure to machine components, which can be used directly for practical applications. In the present research, as the machine tool is miniaturized, the manufacturing machine tools costs less when compared to the equipment used in other micromachining technologies. Moreover, with advancement of micro tool technology, the cutting process can be used to produce micro/meso scale parts. In conclusion, the proposed system can reduce the cost by utilizing the current machining technology, and as a result, complex micro/meso parts can be produced efficiently with high productivity.

• 한국환경생태학회지
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• 제12권3호
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• pp.279-289
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• 1998

상록활엽수림의 식생구조 변화를 모니터링 하기 위하여 완도수목원에 20개의 고정시험구를 1996년에 설치했다. 20개의 고정시험구는 10개의 시험구와 대조구로 구분했으며, 시험구는 적정밀도로 택벌한 후 상록활엽수를 식재했다. 시험처리전 20개 고정시험구의 식생구조는 붉가시나무, 붉가시나무와 개서어나무, 소나무 등이 우점하였고, 소나무군락과 낙엽활엽수군락에서 붉가시나무군락으로 천이되는 식생구조를 나타냈다. 시험처리시험구는 붉가시나무와 소나무가 우점하는 식생구조로 바뀌었고, 관목층과 지피층의 출현종수, 개체수, 피도 등이 증가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.599-602
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• 2002

A novel rapid prototyping (RP) process, an automated transfer type variable lamination manufacturing process (Automated VLM-ST) has been developed. In Automated VLM-ST, a vacuum chuck and linear moving system transfer the plate type material with two pilot holes to the rotation stage. A four-axis synchronized hotwire cutter cuts the material twice to generate Automated Unit Shape Layer (AUSL) with the desired width, side slopes, length, and two reference shapes in accordance with CAD data. Each AUSL is stacked on the stacking plate with two pilot pins using the pilot holes in AUSL and the pilot pins. Subsequently, adhesive is supplied to the top surface of the stacked AUSL by a bonding roller and pressure is simultaneously applied to the bottom surface of the stacked AUSL. Finally, three-dimensional shapes are rapidly fabricated. This paper describes the procedure for generating the cutting path data (AUSL data) f3r automated VLM-ST. The method for the generation of the Automated Unit Shape Layer (AUSL) in Automated VLM-ST was practically applied and fabricated for a various shapes.

• Asian-Australasian Journal of Animal Sciences
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• 제33권8호
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• pp.1242-1251
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• 2020

Objective: The 3×3 factorial arrangement was used to investigate if either high water-soluble carbohydrates (WSC) cultivars or suitable time of day that the grass cut could improve nutrient values and in vitro fermentation characteristics. Methods: The 3 cultivars were mowed at 3 diurnal time points and included a benchmark WSC ryegrass cultivar 'Premium', and 2 high WSC cultivars AberAvon and AberMagic, which contained, on average, 157, 173, and 193 g/kg dry matter (DM) of WSC, and 36.0, 36.5, and 34.1 g/kg DM of N during 7th regrowth stage, respectively. The fermentation jars were run at 39℃ with gas production recorded and sampled at 2, 5, 8, 11, 14, 17, 22, 28, 36, and 48 h. The rumen liquid was collected from 3 rumen fistulated cows grazing on ryegrass pasture. Results: High WSC cultivars had significantly greater WSC content, in vitro DM digestibility (IVDMD) and total gas production (TGP), and lower lag time than Premium cultivar. Methane production for AberMagic cultivar containing lower N concentration was marginally lower than that for AberAvon and Premium cultivars. Grass cut at Noon or PM contained greater WSC concentration, IVDMD and TGP, and lower N and neutral detergent fiber (NDF) contents, but CH₄ production was also increased, compared to grass cut in AM. Meanwhile, the effects of diurnal cutting time were influenced by cultivars, such as in vitro CH₄ production for AberMagic was not affected by cutting time. The IVDMD and gas production per unit of DM incubated were positively related to WSC concentration, WSC/N and WSC/NDF, respectively, and negatively related to N and NDF concentrations. Conclusion: These results imply either grass cut in Noon or PM or high WSC cultivars could improve nutrient values, IVDMD and in vitro TGP, and that AberMagic cultivar has a slightly lower CH₄ production compared to AberAvon and Premium. Further study is necessary to determine whether the increase of CH₄ production response incurred by shifting from AM cutting to Noon and/or PM cutting could be compensated for by high daily gain from increased WSC concentration and DM digestibility.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.322-329
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• 2009

Machinability of LAM(Laser Assisted Machining) has been studied for ceramics such as $Al_2O_3$, $Si_3_N4$ and $ZrO_2$ by $CO_2$ laser. It was possible to remove ceramics by PCBN tool because material became softening and deterioration by local laser beam irradiation. The advantage of LAM is the ability to produce larger material removal rates and tool life. But, for cutting of $Al_2O_3$ and $ZrO_2$, stage of laser power control was needed owing to thermal shock with high temperature of workpiece by laser power. And when $Si_3N_4$ was machined by LAM, $N_2$ gas spouted from surface of one cause of high temperature. Characteristics of LAM were analyzed using pyrometer, dynamometer, SEM and EDS to measure temperature of workpiece surface, cutting force, variation of machining surface and structure of lattice respectively. As the result of this study, it was found that machinability of LAM for ceramics in $CO_2$ laser and mechanism of LAM was different according to the kind of ceramics because of properties of materials.

• 한국작물학회지
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• 제32권1호
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• pp.34-39
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• 1987

페피노(Solanum muricatum AIT)의 증식을 위한 삽목방법과 착과진행을 위한 지베레린(GA$_3$)의 처리시기를 구명하기 위하며 시험한 결과를 요약하면 다음과 같다. 1. 삽목용 상토로는 피트모스(50%)+질석(50%)의 혼합상토가 모래나 일반상토보다 발근수와 발근장이 모두 좋았다. 2. 발근을 위한 생장조절제로는 NAA 1,000ppm 침지처리가 삽목 15 일 후에 발근수와 발근장이 많아 타처리보다도 효과가 컸다. 3. 착과증진을 위한 GA$_3$(50ppm )의 처리시기는 개화기가 좋았고 처리부위는 화기가 좋았다. 4. 지베레린의 처리는 착과효과 이외에도 단위결과를 유도할 수 있었다.

• 한국물환경학회지
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• 제23권3호
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• pp.348-355
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• 2007

We investigated temporal changes of composition, habitat area, growth rate and elements content of hydrophytes at the artificial vegetation island (AVI) in Kyungan Stream within Lake Paldang. We also assessed nutrient removal rate through cutting off the emergent part of hydrophytes. The kinds of hydrophytes have increased from four species (P. australis, P. japonica, T. angustifolia and the Z. latifolia) at initial stage of installation to more than 29 species for 6-year operation. P. japonica was most dominant species at the AVI in 2006. The habitat area of have increased about 2.5 times compared to the initial planting area, occupying 63% of AVI's vegetation area. The incoming species of S. fluviatilis and B. frondosa have adapted successively and expanded habitat area in the AVI. The relative growth rate of P. japonica and P. australis was highest in spring sprouting period. Their hights and weights have increased until summer, by the time they were cutting off the emergent part. They started regrowth immediately after cutting and continued to grow until September and withered away in November. The carbon contents of P. japonica and P. australis have increased during growth phase, on the contrary, the nitrogen and phosphorus contents have decreased. By cutting off and removing the emergent part (leaves and branches) of hydrophytes twice from AVI, $17.6gN/m^2/y$ of nitrogen and $1.3gP/m^2/y$ of phosphorus was removed from AVI in 2006.

• 대한기계학회논문집
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• 제19권8호
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• pp.1832-1843
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• 1995

Tool interference is one of the most critical problems in sculptured surface machining. When machining cavities and concaves, the tool frequently overcuts the portions of the surface, which cause inaccuracy in machining. So tool interference-free paths must be generated for rough cutting more efficiently. In this paper a software using SSI(Surface/Surface intersection) algorithm is developed for eliminating tool interference which occurs in an offset surface in 3-dimensional free form surface modeling. this work consists of two stages : using the offset data, the intersection curves are rapidly checked by this algorithm at the first stage. CL(cutter location) data are obtained by deleting the loop section of intersected offset patches at the second stage. This algorithm can reduce the amount of memory required to store machining data and also easily check region which have the possibility of intersection. Also, This software is verified to be useful in machining a curved object on a DNC milling machine.

• 한국정밀공학회지
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• 제12권9호
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• pp.115-125
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• 1995

부품가공에 있어서 생산성향상을 위하여 버제거를 위한 고도의 기술이 더욱 중요하게 되었다. 특히 CIM 체제에서는 버제거의 자동화를 위하여 가공중에 발생하는 버형성과 파단현상을 정량적으로 예측할 필요성이 더욱 커졌다. 이미 연구된 2차원절삭에서의 버형성 모델을 실제적인 3차원절삭에 적용하기 위하여 기존의 모델을 수정하는 작업이 이루어졌다. 3차원 절삭모델로는 절삭인선에 수직한 면에서의 칩과 공구의 상대운동에 의해서 결정된다고 하는 Rubenstein의 가정이 사용되었다. 본연구에서 다루에되는 롤오버(roll-over) 버는 항상 공구진행방향으로 발생하기 때문에 3차원절삭에서의 버형성을 공구진행방향의 평면내에서의 2차원 절삭의 집합 으로 가정하였다. 공구의 기울림각(inclination angle)이 커질수록 버형성의 크기나 파단면의 크기가 감소하였다. 두종류의 파단이 버형성중에 관찰되었다. 하나는 가공물 끝면에 평행하게 파단면이 발생하였으며 다른 하나는 이에대하여 기울어진 파단이 일어났다. 가공물 끝면에 평행한 경우는 수정된 모델로부터 등가초기공구위치( equivalent initial tool distance)로부터 예측이 가능하며 기울어진 경우는 이결과와 공구의 기울림각으로부터 파단위치를 예측할 수 있다.

• 한국초지조사료학회지
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• 제25권1호
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• pp.33-42
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• 2005

A field experiment was conducted to evaluate growth characteristics, forage production and crude protein yield according to cutting time of Soghum ${\times}$ Sudangrass Hybrid, and decide ideal harvesting time for use of soiling and silage. Experiment design was arranged with 7 different treatment T1(150 m), T2(200 cm), T3(boot), T4(heading), T5(milk), T6(dough) and T7(yellow stage), as a randomized block design. The results were as fellows : Cutting times of utilization during the course of a year was 4 times at T1 and T2, 3 times at T3 and T4, and 2 times at T5, T6 and T7. Accumulative plant length was the highest at T2(666cm), but T3 was the lowest as 402 cm. Mean Leaf length was the highest at T5(82.1 m) and lowest at T7(T1.8 m). Mean leaf width was the highest at T2 and lowest at T6. Stem diameter was orderly ranked as T3(10.7 mm)>T1(9.5)>T2, T5(9.3>T6(8.9)>T7(8.6)>T4(8.5). Stem hardness was orderly ranked as $T7(3.2 kg/cm^2$>T5, T6(2.3)>T3, T4(1.5)> T2(0.6)>T7(8.6)>T1(0.5). Mean of leaf number and leaf ratio was the highest at $T3(8.1\%)$ and $T2(45.3\%)$, respectively. The highest yield of fresh and dry matter was obtained at T4 and T6 as 113,246 and 24,249 kg/ha, respectively(P<0.05), and e lowest at T7 and T1 as 82,675 and 13,006 kg/ha, respectively(P<0.05). Crude protein yield was highest at T6(1.456 kg/ha) and lowest at T3 as 1,189 kg/ha. As mentioned above the result T1, T2 and T3 could be recommended as use of soiling, and T5, T6 and T7 as silage.