• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.617-622
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• 2000

Concentration of pollutants and discharge were monitored regularly at paddy field area during irrigation periods. The amounts of irrigation water during irrigation water during irrigation periods in 1999 were 3690mm. The concentration of pollutants in ponded water are high during fertilizer application period. The ratio of discharge of direct runoff Q$\_$D/ to the total runoff is 9%. The ratios of the load of direct runoff L$\_$D/ to the total load L$\_$T/ are 6% for T-N, 16% for T-P and 16% for COD. It was found that the ratios of the concentration are 0.7 for T-N, 1.8 for T-P and 1.9 for COD. The unit load of T-N, T-P and COD during irrigation periods were 12.1kg/㏊, 0.42kg/㏊ and 85.7kg/㏊, respectively

• 전기의세계
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• v.16 no.1
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• pp.7-13
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• 1967

There are many kinds of motors operating by rated voltage which is constant. In this paper, the characteristics of separately excited direct current motor is analyzed when its terminal voltage is varied as its load current. As for this source, direct current generator of a series field is used, and it is driven at constant speed by a primemover. The induced voltage of the generator is propotional to its load current but it saturates as its load current is large. The charateristics of motor is studied by analog computer because of the nonlinearity of generator. The results are as follows: (1) The load current and the rotor speed of motor increase as the load of motor increases. But the speed of rotor decreases for the influence of the saturation of the iron of generator field when its load current is large. (2) Decreasing the inertia of motor and increasing the inductance of the armature circuit improve the stability of motor and the region of stable state. (3) By changing the field current of the motor, the speed and the direction of rotor can be controlled in wide range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.422-429
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• 2006

Resolved simulations are presented fur gravity current flows aiming at studying their spreading rate. The simulations are performed for two extreme configurations such as planar and cylindrical and for 3 different Grashof numbers: $10^5,\;1{\times}10^6\;and\;10^7$. Varying the size of the heavy fluid release, the study is performed for several phases of spreading, namely acceleration, slumping and inertial phases. For the simulations, efficient spectral multi-domain code is used. From the simulations results it is concluded that 2-D results predicts well the mean front velocity during the slumping phase, but fails to predict it during the inertial phase of spreading. It is also observed that the vortex dynamics of the flow is not reproduced well by the 2-D simulation.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.12
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• pp.1061-1066
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• 2014

Generally electrical circuits are fabricated as PCB(Printed Circuit Board) and mounted on a casing of the product. And it requires lots of other parts and some labor for assembly. Recently a molding technology is increasingly applied to embed simple circuits on a plastic casing. The technology is called as MID(Molded Interconnected Device). Therefore this paper introduces a new MID fabrication process by using direct 3D printing technology.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.1271-1276
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• 2006

DMB 데이터 표준화 위원회는 기존의 방송과 차별화 된 서비스를 제공하기 위하여 MPEG-4 BIFS Core 2D @ Level 1 을 지상파 DMB 데이터 표준으로 선택하였다. 그러나 MPEG-4 BIFS Core 2D @ Level 1 은 비디오 객체 위에 간단한 2D 도형을 오버레이하는 정도의 기능만을 제공하고 있어서, 아직은 DMB 데이터 표준에 3D 데이터 표현에 대한 내용을 포함하고 있지 않다. 따라서 본 논문에서는 향후 DMB 용 데이터 콘텐츠에서 3D 그래픽스를 활용한 멀티미디어 콘텐츠 개발이 가능하도록 3D 그래픽스 표현을 위한 프로파일을 제시하고자 한다. 방송의 새로운 영역인 모바일 환경에서의 BIFS 활용을 위하여 본 연구에서는 MPEG-4 BIFS 의 3D 노드들을 기반으로 모바일 환경에 적합한 노드들을 추려서 프로파일을 구성하였다. 이를 위해 콘텐츠 제작 시 노드 사용 빈도 및 각 노드별 리소스 사용 정도를 조사하였고, 모바일에서 그래픽스 객체 표현을 위한 언어인 OpenGL|ES, JSR184, Mobile Direct3D 등의 표준과 BIFS 표준을 비교 분석하였다. 이러한 조사 내용을 바탕으로 BIFS 3D 노드들 중에서 DMB 용 3D 콘텐츠 구현에 적합한 노드들을 분석하였으며 프로파일 검증을 위한 테스트 콘텐츠를 작성하였다. 향후 멀티미디어 콘텐츠는 다양한 3D 그래픽스 기술의 활용이 예상되므로 이와 같은 연구를 통해 DMB 환경에서도 3D 그래픽스를 객체를 표현이 가능하게 된다면, 다양한 데이터 콘텐츠 개발을 위한 발판이 되어 향후 데이터 방송 활성화에 기여할 수 있을 것이라 기대된다.

• Transactions of Materials Processing
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• v.25 no.3
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• pp.195-202
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• 2016

Direct laser melting(DLM) is an additive manufacturing process that can produce parts by solidification of molten metallic powder layer by layer. The properties of the fabricated parts strongly depend on characteristics of the metallic powder. Atomized powders having spherical morphology have commonly been used for DLM. Mechanical ball-milling is a powder processing technique that can provide non-spherical solid powders without melting. The aim of the current study was to investigate the effect of powder morphologies on the deposition quality in DLM. To characterize the morphological effect, the performances of spherical and non-spherical powders were compared using both single- and multi-track DLM experiments. DLM experiments were performed with various laser process parameters such as laser power and scan rate, and the deposition quality was evaluated. The surface roughness, cross-section bead shape and process defects such as balling or non-filled area were compared and discussed in this study.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1156-1165
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• 2018

This paper presents a detailed realization of direct torque controlled induction motor drive for elevator applications. The drive is controlled according to the well-known space vector modulated direct control scheme (SVM-DTC). As the elevator drives are usually equipped with speed sensors, flux estimation is carried out using a current model where two stator currents are measured and accurate instantaneous rotor speed measurement is used to overcome the need for measuring stator voltages. Speed profiling for a comfortable elevator ride and other supervisory control activities to provide smooth operation are also explained. The drive performance is examined and controllers' parameters are fine-tuned using MATLAB/SIMULINK. The blocks used for flux and torque estimation and control in the offline simulation are compiled for real-time using dSPACE Microlabox. The performance of the drive has been verified experimentally. The results show good performance under transient and steady state conditions.

• Journal of the Korean Society of Radiology
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• v.2 no.4
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• pp.41-46
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• 2008

Computed tomography (CT) is a medical imaging method employing tomography. CT is a 3-Dimensional (3-D) radiographic imaging technique, which is not suited for assessment of inflammation, but can be considered a reference method for assessment of bone damage, due to its direct 3-D visualization of calcified tissue. In this study of pathological joint changes in a rat model of adjuvant-induced arthritis (AIA) and quality analysis of bone destructions were performed by 3-Dimensional computed tomography images. These data demonstrate that the destructive progression of disease in a rat AIA model can be quantified using 3-D CT image analysis, which allows assessment of arthritic disease status and efficacy of experimental therapeutic agents.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.305-312
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• 1995

Weed communities in the dry-direct seeded rice(Oryza sativa L.), soybean(Glycine max(L.) Merr.), and dry-direct seeded rice-soybean rotation system from the transplanted rice field were investigated in order to identify a change in weed species by paddy-upland rotation. Echinochloa species was the most dominant species in the dry-direct seeded rice and their great increase was observed in the continued practices of dry-direct seeded rice. Echinochloa spp., Chenopodium ficifolium, and Digitaria spp. were identified as the major weeds in soybean cultivation in paddy field. Practice of soybean rotation in the dry-seeded rice reduced weed occurrence, particularly at the soybean after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr soybean compared to the continued cultures of rice or soybean. In addition, cultivation of dry-direct seeded rice or soybean culture in the paddy rice field seemed to be helpful for suppression of perennial weeds(Eleocharis kuroguwai, Cyperus serotinus, Scirpus juncoides) and aquatic weeds(Monochoria vaginalis, Sagittaria spp. Potamogeton distinctus).

• Archives of Pharmacal Research
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• v.22 no.4
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• pp.428-431
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• 1999

Seven known oleanolic acid glycosides (1-7) were isolated form the MeOH extract of Tiarella polyphylla. The structures were identified to be 3-O-($\beta$-glucopyranosyl) oleanolic acid (1), 3-O-[$\beta$-D-glucopyranosyl-(1 3)-$\beta$-D-glucopyranosyl] oleanolic acid (2), 3-O-D-[$\beta$-D-glucopyranosyl-(1 2)-$\beta$-D-glycopyranosyl] oleanolic acid (3), 3-O-[$\beta$-D-glucopyranosyl-(1 3)-$\beta$-D-glucopyranosyl] oleanolic acid 28-O-$\beta$D-glucopyranosyl ester (4), 3-O-[$\beta$-D-glucopyranosyl-(1 2)-$\beta$-D-glucopyranosyl] oleanolic acid 28-O-$\beta$-D-glucopyranosyl ester (5), 3-O-[a-L-rahmnopyranosyl-(1 3)-$\beta$-D-glucururonopyranosyl] oleanolic acid (6), and 3-O-[$\alpha$-L-rhamnopyranosyl-(1 3)-$\alpha$-D-glucuronopyranosyl] oleanolic acid 28-O-$\alpha$-D-glucopyranosyl ester (7) on the basis of physicochemical and spectral data. These triterpene glycosides were tested for the anti-complement activity and hemolytic activity. Bisdesmosidic saponins, 4, 5, and 7, showed anti-complement activity; in contrast, monodesmosidic saponins, 1-3, and 6, showed direct hemolytic activity. Methyl esterified monodesmosidic saponins showed anti-complement activity at a low concentration and hemolytic activity at a high concentration.