• Elastomers and Composites
• /
• 제43권3호
• /
• pp.183-190
• /
• 2008

본 연구에서는 polypropylene 복합재료의 내스크래치성을 향상 시키기 위한 연구를 수행하였다. 내스크래치성 개선을 위하여 PP의 분자량이 다른 두 종류의 PDMS계 M/B를 제조하여 각각의 함량에 따른 기계적 물성과 내스크래치성을 평가 하였다. 더 좋은 물성을 보인 마스터배치를 선택하여 grain pattern에 따른 내스크래치성을 평가 하였다. UTM과 편광현미경을 통하여 기계적 물성과 스크래치성을 평가 하였다. Color 3D laser Scanning microscope로 표면 grain pattern 형상을 관찰하였다. 마스터배치의 분자량과 함량에 따른 기계적 물성의 차이는 비교적 적은것으로 평가 되었으며 내스크래치 평가에서는 고분자량의 M/B를 첨가함에 따라 내스크래치성이 향상 되는 것으로 나타났다. Grain pattern에 따른 스크래치 평가에서는 grain pattern이 깊이가 깊고 불규칙하며 그 형태도 크고, 둥근형일 때 내스크래치성이 우수한 것으로 나타났다.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권12호
• /
• pp.1544-1553
• /
• 1999

Recently, ultrasonic testing techniques have been widely used in the evaluation of the quality of metal. In this experiment, six heat-treated temperature of specimen have been considered : 0, 1200, 1250, 1300, 1350 and 1387$^{\circ}C$. As heat-treated temperature increases, the grain size of stainless steel also increases and then, eventually make it destroy. In this paper, a pattern recognition method is proposed to identify the heat-treated temperature of metals by evidence accumulation based on artificial intelligence with multiple feature parameters; difference absolute mean value(DAMV), variance(VAR), mean frequency(MEANF), auto regressive model coefficient(ARC), linear cepstrum coefficient(LCC) and adaptive cepstrum vector(ACV). The grain signal pattern recognition is carried out through the evidence accumulation procedure using the distances measured with reference parameters. Especially ACV is superior to the other parameters. The results (96% successful pattern classification) are presented to support the feasibility of the suggested approach for ultrasonic grain signal pattern recognition.

• 한국농공학회지
• /
• 제17권3호
• /
• pp.3878-3884
• /
• 1975

This study was carried out to develop the throw-in type thresher with its size as small as possible. Developing the smallest possible size of the throw-in type thresher has been very important to increase mobility and to reduce the machine price. The thresher that developed for this purpose was tested as to threshing and separation performance for the samples collected in eight catch boxes under the concave while threshing. The amount of grain collected in each compartments was measured and the threshing and separating pattern along the total span of the threshing drum was determined. The performance of separating and threshing units of the test thresher and threshing loss was evaluated by use of the developed grain separating apparatus and the method for measuring the grain separating performance of threshers. The results are summarized as follows; 1. The unthreshed grain (drum losses) and semi-threshed grain did not appeared at all throughout the treatments. 2. When threshed by making use of the developed throw-in type thresher, the threshing grain loss at about 25 per cent grain moisture was about one-half when threshed at about 18 per cent grain moisture. 3. And its grain separating loss in higher feed rate was decreased in comparison with that of lower feed rate. These results suggests that the throw-in type thresher may be suitable for wet threshing and for higher feed rate of threshing. 4. Above 60 per cent of total grain passing through concave fell through the screen within a scant 30 cm from the feeding inlet. This threshing pattern may suggest that major threshing action may be finished before about one third of cylinder length. The required separating load extended over the whole drum span is so defferent that separating elements should be redesigned so as to accomodate this variable pattern of separation load. 5. It was apparent from the experiment that the length of the threshing drum of the throw-in type thresher could be reduced from 1285mm to about 1050mm without increasing grain separation loss greatly.

• 한국의류산업학회지
• /
• 제10권6호
• /
• pp.989-996
• /
• 2008

The purpose of this study is to provide the basic knowledge for the pattern development of a flared skirt. Two flat pattern (FP) methods, the concentric circle method and the corrected concentric circle method, and a draping were used for pattern making. Using these patterns, skirts were made with lengthwise grain in the centerline. The influence of pattern making method on the silhouette of the flared skirt was evaluated by the hemlines formed at the skirt worn in a dress form. Moreover, the combined influence of pattern making method and cutting direction on the silhouette of the flared skirt was examined with the draping pattern (DP) skirt and a FP skirt with $45^{\circ}$ bias grain in the centerline. The DP skirt had more uniform nodes and formed a stable wave form than the FP skirts throughout the whole hemlines. The number of nodes was reduced with lining in the two FP skirts, whereas the number of nodes was not changed in the DP skirt. The unit wave form of all the skirts by three patterns showed long loop form, and the slope angles of the unit wave form of the two FP skirts were higher than that of the DP skirt. The silhouette of the flared skirt was highly influenced by the shape of the waist circumference line in patterns. The DP skirt with lengthwise grain in the centerline showed good silhouette with uniform nodes and high marking efficiency, compared to the FP skirt with $45^{\circ}$ bias grain in the centerline.

• Fisheries and Aquatic Sciences
• /
• 제2권2호
• /
• pp.210-217
• /
• 1999

Chemical oxygen demand (COD), phytoplankton cell number and chlorophyll-a concentration (Chl-a), sediment mean grain size and ignition loss were studied to determine their temporal trends in the study area. Historical data of COD, cell number and Chl-a were gathered from the late 1960s or early 1980s to 1997, and trends in temporal domain were obtained from a simple regression. Sediments for grain size and ignition loss (as organic contents in sediments) were sampled from the Chokchon macrotidal flat bimonthly from September 1990 to November 1996, and were analyzed using the decomposition method of time series analysis. In general, the first three data showed increasing trends based on regression analysis. The trends of sediment grain size fluctuated in a neutral pathway while those of ignition loss yielded no increasing pattern. In contrast with the suggestions from Ahn and Choi (1998) who reported a coarsening variation in sediment grain size to be a cause of the directional and remarkable changes of macrofaunal communities in this area, we could not find such a corresponding variation pattern from our samples. In diagnosing eutrophication, a paradoxical phenomenon was encountered between the trends in water column (COD, cell number and Chl-a) and sediment (ignition loss) data. In this paper, we inferred the possible processes that produce the discrepancy. Some explanations and biological responses to eutrophication were predicted and discussed.

• 한국지형학회지
• /
• 제26권1호
• /
• pp.15-26
• /
• 2019

In this study, we investigated the grain size, lithological type, and shape of coarse bed materials in the upper and middle reaches of Gongneungcheon River. For this purpose, 11 sampling points were selected along the river. For 100 samples of the coarse bed materials at each point, three axes (long, intermediate, and short) of samples were measured, and their lithological types were also identified. By measuring grain size, the sphericity and flatness of samples were calculated. Finally, every particle was classified into four shape categories: sphere, disc, blade and rod. We found that the grain size in incised meandering reach is the largest. This is mainly due to the supply of coarse materials from steep valley sides along the meandering channel. According to the lithological analysis, all samples were identified as granite, gneiss and schist, and quartz. The proportion of granite decreased, whereas the proportion of gneiss and schist increased downstream. These patterns indicate that the bedrock distribution within the study area accounts for the downstream lithological variation of coarse bed materials. With regard to the grain shape, sphericity gradually decreased while flatness gradually increased downstream. In the case of the shape classification, unlike the general downstream pattern of grain shape, the proportion of the sphere type decreased and the proportion of the blade type increased downstream. Such a reversal change in the downstream direction turns out to be determined by the lithology (such as foliation, bedding and the pattern of weathering) of coarse bed materials.

• 한국잡초학회지
• /
• 제30권2호
• /
• pp.68-83
• /
• 2010

Weedy rice (Oryza sativa L.) occurred sympatrically with other weeds and the rice crop in Malaysian rice granaries. We conducted field surveys in 2006-2008 seasons in 7 farm blocks of Selangor's North West Project, Malaysia to enlist the new biotypes of weedy rice (NBWR) and assess their spatio-temporal pattern of distribution based on quantitative and dispersion indices. No less than 16 accessions of NBWR were identified based on their special traits, viz. panicle type, pericarp colour, presence or absence of awn, seed type and degree of grain shattering. The NBWR accessions exhibited a combination of morphological traits from open panicle, grain with awns, red pericarp, short grain type, and degrees of grain shattering. Others mimic commercial rices with close panicle, awnless grains, white pericarp, long or short grain-type. Invariably, the NBWRs mimic and stand as tall as cultivated rice namely MR219, MR220, or MR235 and these NBWR accessions stand among equals morphologically vis-a-vis the commercial rice varieties. Most accessions displayed varying degrees of grain shattering in excess of 50%, except Acc9 and Acc12. The seasonal dynamics of on the prevalence of dominant NBWR accessions were also displaying significant differences among farm blocks. While Bagan Terap farm block, for example, did not record any measurable changes in the dominant NBWR accessions over seasons, the Sungai Leman farm block recorded measurable season-mediated changes in the dominant NBWR accessions. Sungai Leman started with NBWR Acc3, Acc4, Acc5, Acc7, Acc8, and Acc12 in season 1 of 2006/2007, but no measurable records of Acc3 and Acc5 were shown in season 2 of 2007. In season 3 of 2007/2008, only Acc8 and Acc12 prevailed in the farm block. In Sawah Sempadan farm block, season 3 of 2007/2008 showed much reduced prevalence of NBWRs leaving only Acc8 and Acc12. Most accessions registered clump or under-dispersed spatial distribution pattern based on quantitative indices: variance-to-mean ratio (VMR) and Lloyd's patchiness values. The dynamics on the extent of infestation and prevalence of dominant NBWR accessions registered both season- and farm-block mediated differences. Most accessions showed VMR >1 thus indicative of having a clump or clustered spatial distribution, as exemplified by Acc3, Acc4, Acc7, Acc8 and Acc12 in all farm blocks throughout three seasons. Some accessions have either random or uniform distribution in a few farm blocks. The Acc8 has the highest population counts based on important value index, followed by Acc12, and both were the most dominant accession while Sawah Sempadan was the worst farm block infested by NBWR compared to other farm blocks. These results were discussed in relation with the current agronomic and weed management practices, water availability and extension services in the granary.

• 한국초전도ㆍ저온공학회논문지
• /
• 제19권2호
• /
• pp.9-13
• /
• 2017

This study presents a simple method to control the seed orientation which leads to the various growth characteristics of a single grain REBCO (RE: rare-earth elements) bulk superconductors. Seed orientation was varied systematically from c-axis to a-axis with every 30 degree rotation around b-axis. Orientations of a REBCO single grain was successfully controlled by placing the seed with various angles on the prismatic indent prepared on the surface of REBCO powder compacts. Growth pattern was changed from cubic to rectangular when the seed orientation normal to compact surface was varied from c-axis to a-axis. Macroscopic shape change has been explained by the variation of the wetting angle of un-reacted melt depending on the interface energy between $YBa_2Cu_3O_{7-y}$ (Y123) grain and melt. Higher magnetic levitation force was obtained for the specimen prepared using tilted seed with an angle of 30 degree rotation around b-axis.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2001년도 추계학술발표대회 개요집
• /
• pp.220-222
• /
• 2001

The average grain size, the grain-size distribution, the morphology and the microstructure are fundamental characteristics of a spraying powder. Now that the significance of the grain size for the pattern of properties of the powder has been recognised, greater consideration is also being given to it in standards and regulations. However, unfortunately, the processes according to which the grain size and the grain-size distribution must be determined are specified in the rarest of cases. The contribution therefore dealt with the comparison of different particle-size measuring techniques, such as diffraction spectroscopy, sedimentation, sieving and microscopic measurement. The comparability of the measured results was investigated on twelve plasma spraying powders with different compositions, nominal sizes and morphologies.

• 한국식생활문화학회지
• /
• 제10권4호
• /
• pp.235-239
• /
• 1995

After 1960, staple food consumption pattern of Korea underwent a significant change from the former rice-barley pattern to the present rice-wheat pattern. Therefore the present staple food consumption pattern of Korea may be defined as a mixture of grain and flour consumption.