• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2811-2816
• /
• 2007

We conducted a numerical study of AC-electroosmotic (alternating current) effect on the fluid flow and mixing in a 3-D microchannel. The microchannel used as an efficient micro-mixer is composed of a channel and a series of pairs of electrodes attached in zigzag pattern on the bottom wall. The AC electric field is applied to the electrodes so that a steady flow current takes place around the electrodes. This current is flowing across the channel and thus contributing to the mixing of the fluid within the channel. We performed numerical simulations by using a commercial code to obtain a steady flow field. This steady flow is then used in evaluation of the mixing performance via the concept of mixing index. It was found that good combination of two kinds of electrode, which gave us a good mixing, is not simple harmonic. And when the length ratio of these two kinds of electrode is 2:1, we can get the best mixing effect.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2004년도 춘계학술발표회논문집
• /
• pp.177-182
• /
• 2004

This study presents the application of aerial photographs and KOMPSAT-1 Electro-Optical Camera(EOC) imagery in detecting the change of an urban area that has been rapidly growing. For the study, we used multi-time images which were acquired by two different sensors. For all of the images, the coordinate reference system and scale were first made identical through the 1st and 2nd geometric corrections and then image resampling were carried out to spatial resolution of 7m to detect changes under the same conditions. The Image Differencing was employed as a change detection technique. It was confirmed to be able to detect the changes of terrestrial surface like building, structure and road features from aerial photos and KOMPSAT EOC images with single band. The changes could be detected to some extent with the images acquired from different kinds of sensors as well as the same kinds of sensors.

• 한국연초학회지
• /
• 제18권1호
• /
• pp.12-20
• /
• 1996

The spermatogenesis and chromosome number were investigated in the pupal testes of Helicouerpa assulta Guenee by light microscopy. During the spermatogenesis, each bundle of P8(256) sperms developed by 6 mitotic and 2 meiotic spermatogonial divisions. From the early stage of spermatogenesis, it was distinguishable between two kinds of sperm differentiation, eupyrene and apyrene spermatogenesis, which are characteristic in Lepidoptera, by the differences in nuclear shape and cell distribution in immature spermatocyst. Through the followed spermiogenesis, the spermatocysts were developed into two kinds of mature cyst, a streamline-shaped eupyrene cyst with nucleated sperms of thready head or a long spindle-shaped apyrene cyst with anucleated sperms of cylindrical head. As the results off chromosomal analysis at metaphase of the spermatogonial mitosis and spermatocytic meiosis, the chromosome number were 2n=6a/n=31, respectively, and no variation between individuals.

• 한국생산제조학회지
• /
• 제8권4호
• /
• pp.93-98
• /
• 1999

Currently the technology of surface finishing is highly demanded in a wide range of industries. And many kinds of surface finishing technologies have been developed for each purpose. But it is still difficult to make a fine surface for the part which has three dimensional geometry. Now most of these kinds of complex parts are polished by hand by well skilled workers, This hand work process is inefficient and the production cost is high. Therefore it is desirable to develop a new finishing technology to solve problem In this study a new device was developed and tested in various test conditions.

• 가정과삶의질연구
• /
• 제4권1호
• /
• pp.49-69
• /
• 1986

This study aimed to fine out the rational quantity of kitchen utensils and appliances Questionnair was distributed to families of 469 of middle school students. I studied status of kitchen work centers, quantity and the kinds of kitchen utensils. The results were as follows. 1. the status of kitchen :1) The percentage of western style work centers was significantly higher than the average level of Seoul. 2) The length and the height of work centers were below standard. 3) Arrangement of work centers was relatively correct, however, the kinds of kitchen work centers were not fully equipped. 2. The quantity of kitchen utensils: The socio-economic status were the main factor of the quantity of kitchen utensils. Educational level, income level and floor space were strongly corrected to the quantity of kitchen utensils.

• 대한기관식도과학회지
• /
• 제10권2호
• /
• pp.5-8
• /
• 2004

Stenosing airway disease is classified as intraluminal obstruction, extrinsic compression, and malacia by the anatomical site of the lesion. Stenting therapy is indicated for symptomatic relief of life-threatening dyspnea caused by the last two types. Airway stents are made with metal mesh and/or silicone rubber, and currently more than 20 kinds of stent are available. Among many kinds of silicone stent, the Dumon stent is mostly widely used for benign and malignant airway stenoses, but general anesthesia and rigid bronchoscopy are needed for insertion. It can be removed when the stenosing airway disease subsides completely. In many clinical studies, most patients $(85-90\%)$ improved immediately after stenting, and procedure-related mortality was low $(<3\%)$ in experienced centers. Stent displacement, mucus impaction, and granulation tissue formation are potential complications. Stenting is one of many effective therapeutic modalities for stenosing central airway disease. Careful patient selection, experiences, and continuous development of new technology will bring better results.

• 한국통신학회논문지
• /
• 제19권11호
• /
• pp.2067-2080
• /
• 1994

최근, 디지털 이동 통신 시스템에서, Blind 등기화와 Carrier Recovery의 결합에 관한 관심이 점점 증가하고 있다. 본 논문에서는 변조된 QAM신호를 위한 Blind 등화기와 다양한 Carrier Recovery의 결합한 새로운 수신기를 제시하였다. Godard blind 등화기, Map estimation Costas loop, Generalized Costas loop, Leclert loop, Angular Form loop를 간단히 검토한 후, 등화기와 CR loop의 결합형태를 갖는 두가지 수신기 구조를 제시한다. 몬테 카를로 시뮬레이션 기법을 사용하여, 본 논문에서 제시한 두가지 수신기 구조가 정상상태에서 잘 동작 됨을 확인할 수 있다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 봄 학술발표회 논문집
• /
• pp.145-152
• /
• 1999

In the applying of the reinforced soil method, it would be possible to obtain reinforcement effect more than before in terms of economic if high water content clayey soils could be used as embanking material. Futhermore it would be possible to expect the expansion of the applying field of reinforced soil method too. In this study, the authors describe the analysis results on the behavior of 5 meter high walls reinforced with nonwoven geotextile having the permeability and woven geotextile or geogrid having large tensile strength on the soil ground. The behavior of the walls were investigated for about 100 days after construction and the deformations of reinforcements, lateral soil pressures, vertical and horizontal displacements of the walls were examined by automatical measuring system. It was found that this kinds of reinforcing system might effectively improve the performance of the steep walls by virtue of the reciprocal action between soil and reinforcements, and it might be concluded that construction of the clayey reinforced soil walls with three kinds of geotextiles could be done successfully even on the comparative weak ground.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 봄 학술발표회 논문집
• /
• pp.121-128
• /
• 1999

Recently, research of reinforcement mechanism in a sense of soil mechanics has been under way by many researchers with developing various kinds of geoteutiles. But it must be consider that reinforcement effect largely depends on used geotextile even if it is used on same in-site condition. As a matter of fact it is not necessarily that reinforcement effect appears in all the case of reinforced soil construction. It means that appropriate geotextile coincided with the intention has to be selected and adequate examination is needed. In this study, reinforcement effect with various kinds of geotextiles are compared through a series of direct shear tests. Based on the test results, shear strength characteristics and reinforced effects are investigated quantitatively and qualitatively considering the confining stress, reinforcement characteristics and number of reinforcement.

• 펄프종이기술
• /
• 제36권4호
• /
• pp.49-59
• /
• 2004

This study was carried out to obtain the basic data for producing higher functional coating agents for pulp mold by evaluating various kinds of starch derivatives. At that time, four kinds of starch derivatives were manufactured for making coating agents respectively. Physical properties of coated paperboards were tested. Conclusions obtained from this results were as follows. The water and oil resistance of hydroxypropylated, cyanoethylated and carboxymethy­lated starch were high when degree of molar substitution(DS) of propylene oxide, acrylonitrile and sodium monochloroacetate were 0.18, 0.07 and 0.009, respectively. Also, the those of crosslinked starch were high when degree of crosslinking of epichlorohydrin was 0.02. Consequently, $8\%$ solution of carboxymethylated starch made with DS 0.009 of monochloroacetate was the best among coating agents from starch derivatives men­tioned above.