• 한국초지조사료학회지
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• 제5권1호
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• pp.84-89
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• 1985

1. Alfalfa의 조단백질(粗蛋白質)은 채취시기가 경과함에 따라 1회(回) 19.64%에서 4회(回) 12.37%로 낮아졌으며, 조섬유, CWC, Cellulose도 낮아지는 경향을 보였다. Orchard grass도 조단백질(粗蛋白質)은 1회(回) 13.79%에서 2,3회(回) 12.97, 12.85%로 낮아졌으며 4회(回) 14.72%로 다소 상승하였다. 그밖에 조섬유, CWC는 채취시기가 진행됨에 따라 낮아졌으며 Cellulose는 시기에 다소 증가하였으나 그후 감소하였다. 2. Alfalfa와 Orchard grass의 DM과 Cellulose 소화율(消化率) Alfalfa의 채취시기별 DM 소화율은 1, 2, 3회(回) 51.80, 51.86, 52.92%로 별반 차이가 없었으나 4회(回) 59.52%로 가장 높았고 점차적으로 채취시기가 경과함으로써 증가하는 경향을 보였다. Cellulose 소화율은 3회(回) 시기에 감소하였다가 4회(回)에 약간 상승하였다. Orchard grass의 DM소화율은 1,2,3,4회(回)에 62.21, 66.10, 60.95, 66.32%로 2회(回) 채취초기에 소화율이 높아졌고 3회(回)에 다소 감소하였다가 4회(回)에 증가하였다. Cellulose 소화율은 Alfalfa와 마찬가지로 3회(回) 시기에 감소하였다가 4회(回)에 약간 상승하였다. 3. Alfalfa와 Orchard grass의 발효율(醱酵率) 및 발효속도(醱酵速度) 측정(測定) Alfalfa의 채취시기별로 볼 때 DM의 시간당 발효율은 1회(回)가 0.83%로 가장 높았으며 3, 4회(回)는 별반 차이가 없었다. 또한 Cellulose의 발효율(醱酵率)도 1회(回) 시간당(時間當) 1.29%로 가장 높았고 2,3회(回)에 감소하였다가 4회(回)에 다소 증가하였다. Orchard grass의 DM 소화속도(消化速度)는 1회(回)에서 4회(回) 1.42, 1.58, 1.60, 1.57%로 2.3회(回) 채취시에 빠른 경향을 보였으며 Cellulose는 2회(回)에 1.77%로 가장 높았다.

• 한국정밀공학회지
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• 제25권6호
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• pp.40-46
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• 2008

Ultraprecision cutting of steels with geometrically defined single crystal diamond tools is handicapped by excessive tool wear. This paper presents a new approach to suppress the wear of single crystal diamond tool in cutting of steels. In general, it is said that the wear of diamond tool is caused by chemically reactive wear under high temperature and high pressure conditions. In order to suppress such chemical reactions, the time of contact between the diamond tool and the steel work in cutting was controlled by employing the intermittent cutting method such as fly-cutting. Series of intermittent cutting experiments have been carried out to control the tool-work contact time by changing one cycle of cutting length and cutting speed. The experimental results were shown that the tool wear was much dependent on the contact time regardless of the cutting speed, and that the wear was much suppressed by reducing the tool-work contact time. It is expected that the steels can be successfully cut with a single crystal diamond tool by controlling the contact time.

• 한국생산제조학회지
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• 제26권1호
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• pp.13-19
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• 2017

In modern industry, the machining process is very important for manufacturing various products. More than 80% of machining processes apply rough cutting. The target of this study is to establish the optimal condition of rough cutting using trochoidal motion for improving productivity. For research, the range of cutting conditions is defined by trochoidal motion. The cutting time and tolerance are measured and evaluated according to the cutting conditions of machining. Experimental data are utilized for comparing trochoidal motion and contouring. It is found that the cutting time of trochoidal motion is two times less than that of contouring with optimal cutting conditions. To conclude, trochoidal motion for rough cutting under appropriate cutting conditions improves productivity and shortens processing time significantly.

• 한국초지조사료학회지
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• 제7권1호
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• pp.18-24
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• 1987

This experiment was carried out to investigate the effects of the final cutting time and cutting height on the winter survival, regrowth, and carbohydrate reserves in stubble, and early spring yield of orchardgrass-dominated pasture before and after the winter season. The experiment was conducted at the experimental field of the Livestock Experiment Station, in Suwon, from October 1985 to early 1986. The results obtained are summarized as follows: 1. Regrowth of plant after the final cut increased significantly (P<0.05) with plot of the early cutting time (Oct. 10) and high cutting height at the final. For winter survival, cut plant should regrow over 15cm in plant height. Therefore limit cutting time and cutting height were forced to be on Oct. 25 and at 6-9cm, respectively. 2. Total water soluble carbohydrate (TSC) content in stubble after the final cut was not significantly changed by different cutting time and cutting height. 3. The percentage of dead plant after wintering was found to be high with plot of the late cutting time and low cutting height at the final cut (P<0.05). And the correlation between the percentage of dead plant after wintering and final plant height before wintering was significantly negathe (r = -0.728**). 4. Fresh and DM yield at the early spring after wintering were increased in the plot of the early cutting time and high cutting height (P<0.05) at the final cut. And significantly positive correlation was observed between the early spring yield and final plant height before wintering (r = 0.720**).

• 한국정밀공학회지
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• 제15권11호
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• pp.9-20
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• 1998

In recent manufacturing process, the increase of productivity has been attempted by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage and have a bad effect on both manufacturing machine and workpiece. Thus, it is necessary to estimate and control the cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real-time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. Since the actual cutting force follow the reference force, resulting the reducing of the machining time the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without sensor and applied to several workpieces. Experiments show that the suggested method is effective to cutting force control of a CNC machining center.

• 한국기계가공학회지
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• 제12권1호
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• pp.84-89
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• 2013

Titanium used in industry has been widely applied for aerospace engine, structures and spacecraft exterior, etc. because the titanium is higher in strength compared to the steel and light in weight compared to the steel. This study is to investigate the effect of cutting depth and cutting time on the spindle speed and feed rate of vertical machining center as a parameter to find the rough cutting time and cutting depth in the medium speed cutting machining of the titanium alloy. It is found that the cutting machining heat are increased as the cutting depth, feed rate, cutting time and spindle speed are raised.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.660-663
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• 1997

In recent manufacturing process, the increase of productivity is required by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage, and have a bad effect on both the manufacturing machine and the workpiece. Thus, it is necessary to estimate and control cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. By reducing the machining time resulting from making the actual cutting force follow the reference force, the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without the force sensor, applied to several workpieces. Experiments show that the suggested method is superior to the conventional method operated by constant feedrate.

• 한국기계가공학회지
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• 제12권5호
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• pp.129-134
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• 2013

Titanium used in industry has been widely applied for aerospace important parts and automobile important parts, etc. because the titanium is higher in strength compared to the steel and light in weight compared to the steel. This study is to investigate the effect of cutting tool cooling method and cutting time on the spindle speed and feed rate of vertical machining center as a parameter to find the rough cutting time in the medium speed cutting machining of the titanium alloy. It is found that the cutting machining heat are increased as the feed rate, cutting time and spindle speed are raised.

• Journal of Welding and Joining
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• 제30권4호
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• pp.44-48
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• 2012

H-beam used for stiffening the upper structure of ocean plant is cut in the various shapes. The cutting process of the H-beam is done manually and requires a long time and high cost. Therefore, automation of H-beam cutting is an important task. This research aims to develop a 3-D simulator to build the automatic H-beam cutting system and to determine the optimal cutting method. The automatic H-beam cutting system composes of 6 robots including 2 cutting robots hang to a crane and 1 conveyer. The appropriate system layout for covering the various sizes and types of H-beam was tested and determined using the simulator. The H-beam cutting system uses a hybrid type of plasma and gas cutting because of special cutting shapes of H-beam. The cutting area of each cutting method should be properly divided according to the size and shape of H-beam to shorten the total cutting time. Additionally the collision between a robot and a robot or a robot and H-beam should be avoided. The optimal cutting method for the shortest cutting time without the collision could be found for the various cutting conditions by use of the simulator. 2 simulation samples shows the availability of the simulator to find the optimal cutting method.

• 한국유기농업학회지
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• 제3권1호
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• pp.71-78
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• 1994

This experiment was conducted to investigate the effects of mixed application of earthworm cast and N-fertilizer on dry matter(DM) yield in orchardgrass(Dactylis glomerate L.). Experimental plot were designed by a randomized block design with 3 replications of six different treatments-Control(0:0), 100% earthworm cast(0:100), 3 levels of mixed application(25:75:, 50:50, 75:25) of earthworm cast and N-fertilizer, and 100% N-fertilizer(100:0)based on content (%) of nitrogen. The experiment was carried out from March to October, 1993, on the forage experimental field of Kon-Kuk Univ. in Seoul. The results obtained are summarized as follows: 1. Annual dry matter yield was significantly increased according to increasing of N-fertilizer 2. Dry matter yield for each treatment as cutting time was passing was decreased. However, dry matter yield was slightly increased at 75%, 50%, and 25% mixed application of earthworm cast at the third cutting time than the second cutting time(p<0.05). 3. concerning each treatment per cutting time, dry matter yield was higher at 100% N fertilizer than the other treatments at the first, second, and fourth cutting time except the third cutting time only(p<0.05). And according to decreasing of mixing ratio of N fertilizer, dry matter yield was decreased, too. 4. Dry matter yield of 100% earthworm cast was significantly higher than control at the fourth cutting time(p<0.05).