• 한국운동역학회지
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• 제28권2호
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• pp.87-92
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• 2018

Objective: The purpose of this study was to investigate the factors affecting two kinds of bat swing behavior through kinematic analysis. Method: A total of 32 high school baseball players participated in this study. The ball was placed on the tee-ball in a position where the subject could easily swing and the standard bat swing was performed as quickly and as accurately as possible using aluminum bats and wooden bats. Results: The aluminum bat showed a rapid swing speed of about 1.79 m/sec compared to the wooden bat. The speed of the batted ball was found to be significantly greater for the aluminum bat than for the wooden bat. In addition, although the difference between the shoulder-pelvis rotation angle according to the type of bat was not indicated, there was a statistically significant difference between the aluminum bat and the wooden bat in terms of the rotational angular velocity. Conclusion: Even though the results can explain the difference between the bat swing speed and the speed of the batted ball depending on the bat's material, it is difficult to explain the difference depending on the type of bat at the shoulder-pelvis rotation angle. However, shoulder-pelvic rotation angular velocity appears to be higher for the aluminum bat, and the differences in the type of bat is considered to be related to the batting swing factor.

• Journal of the Korean Wood Science and Technology
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• 제52권3호
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• pp.276-288
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• 2024

This study was conducted to reproduce the woodworking process of Baekje wooden storage facilities. Green timber of Quercus spp. was processed using ancient woodworking tools, and the tool-trace formed in this process were compared with the tool-trace of actual excavated artifacts. In the tool-trace analysis, the length and shape of the tool-trace were objectively recorded using a 3D Scan, and that were difficult to confirm with photograph were confirmed through stereoscopic microscope. As a result, there were two types of adze's tool-trace. One of them is minute straight Blade-top trace line when trimming the wood surface and the other is Plucked trace that appear when strongly chop at the wood. When a chisel bat was not used, a long and wide continuous shape blade trace was produced. And when the chisel head was struck with the chisel bat, a straight blade-top trace was regularly observed. Saw-trace was identified in several layers with fine straight stripes. Through this, it was found that the tool-trace of the woodworking tools, which is estimated to have been used in each process, and the tool-trace remaining in the Baekje wooden storage facility coincide.

• Journal of the Korean Wood Science and Technology
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• 제43권6호
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• pp.777-783
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• 2015

이방성 물질인 목재는 방향별로 나타나는 세포종류, 크기, 배열에 따라 경도, 성질, 치수변화등 서로 다른 성질을 나타낸다. 또한 사용용도에 따라 다양한 형태로 이용할 수 있는 재료이다. 그러나 동일수종의 목재 내에서도 변이성이 나타나기 때문에 각각의 고유성질과 용도에 대해 정확히 파악하고 이론 및 기술 등의 정립을 통해 재료 이용의 극대화를 위한 연구가 필요하다. 목재의 물리적 특성 및 밀도와 탄성계수의 관계에 관한 연구는 국내외로 다양하게 이루어져 왔으나 대부분 규격화된 시편으로 얻은 값을 통해 상관관계를 분석해왔으며 목재 완제품에 적용한 연구가 거의 없는 실정이다. 또한 야구배트에 대한 진동거동 및 타격에 관한 논문은 많이 있으나 목재 배트를 재료로서 물성을 분석한 연구가 미비한 실정이므로 이와 관련된 연구가 필요하다. 본 연구에서는 캐나다산 경단풍나무로 제작한 배트의 실제완제품을 이용하여 소재물성을 파악하고 주파수 비교를 통해 탄성계수를 분석하고자 한다. 소재물성 비교를 위해 배트의 연륜분포와 밀도 등 기초물성을 조사하였고 공진주파수와 관계식(ASTM C1259)을 통해 탄성계수를 산출하여 재료의 반발력을 산출하였다. 공진주파수 증가에 따른 연륜분포 비교에서 감소하는 경향을 나타냈다. 섬유방향에 따른 가진 각도별 비교에서 섬유방향과 수직한 $0^{\circ}$ 방향으로 가진할 때보다 수평한 $90^{\circ}$ 방향으로 가진할 때 탄성계수 값이 높게 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.493-508
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• 2023

Round timber materials of 600 mm length, cut from large-cross-section round timber of red pine (Pinus densiflora S. et Z.) of 450 mm width and 4.2 m length, were prepared as the target of kiln drying in this study. After treating the target materials through end sealing (ES), end sealing - kerfing (ES-K), lateral sealing - end sealing - boring (LS-ES-B), or lateral sealing - partial end sealing (LS-PES), the effects of the treatment on the incidence of drying defects were determined. The target materials with exposed lateral surface and sealed cross surface were steamed at the initial temperature of 65℃ above the official pest control temperature of 56℃, followed by kiln drying toward the final temperature of 75℃. The target materials with sealed lateral surfaces, on the other hand, were dried at the initial temperature of 90℃ at almost the maximum temperature of conventional kiln drying, as there is no risk of early check formation caused by surface moisture evaporation. The final temperature was set at approximately 100℃. The drying time, taken for the target materials with initial moisture content of 70%-80% to reach the target moisture content of 19%, varied across treatment conditions. The measured drying time was 1,146 hours (approximately 48 days) for the timber with sealed cross surface and 745 hours (approximately 31 days) for the timber with sealed lateral surface, until the moisture content reached the target level. The formation of surface checks could not be prevented in the control and ES groups, but a definite preventive effect was obtained for the LS-ES-B and LS-PES groups.

• 보존과학회지
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• 제36권1호
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• pp.15-27
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• 2020

The Main Hall of the Fengguo monastery in Yixian county, Liaoning province, China, is the best preserved and largest wooden Buddhist structure, typical of the Liao dynasty style, in China. However, some degradation to the timber frame of the Main Hall has been noted, and this is causing concern in terms of the long-term preservation of the structure. In this study, wooden pillars showing the degradation phenomena of whitening, for areas in contact with the stone floor, and extensive surface damage at higher locations(mostly above 1 m) have been examined. Samples taken from wooden pillar surfaces were analyzed using X-ray powder diffraction, Fourier-transform infrared spectroscopy(FTIR), ion chromatography, and pH measurements. With respect to the whitening phenomenon, we found inorganic calcium precipitates and oxalate ions, along with higher pH values. These symptoms indicated that chemical changes were taking place in response to alkaline conditions, suggesting that alkaline mixtures with calcium content in the foundations may be responsible. Regarding the upper surface-damaged areas, no valid evidence for chemical degradation was found using FTIR analysis, while damaged areas exhibited the presence of more bat guano-related materials than which were apparent in undamaged areas. The occurrence of this surface-damaged phenomenon has therefore been attributed to physical damage caused by bat activity over long periods of time.

• 대한가정학회지
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• 제29권2호
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• pp.87-120
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• 1991

The purpose of this study was to identify the design characteristics of the multi-leveled chest(jang) which was the main furniture of the master bedrom(anbang) in the Chosun Dynasty. The major findings and conclusions were: 1. The front view of the multi-leveled chest were composed of a protruded top panel(kaepan), drawers, folded doors, sectional panels(chwibyok kan and morum kan) and base stand(madae) in general. Variety in the front view found more frequently in single level chests than bi- or tir-level chests. 2. The overall dimensions of each type of chest increased with increase in number of levels, but the height of the sectional parts decreased. That is, the overall proportion of the single level chests were 10 : 9, bi-level chests were 5 : 6, and tri-level chests were 2 : 3. The proportion of 1 : 1, 4 : 5, 1 : 3, 1 : 4, 1 : 5 were found often in the sectional parts such as drawers, doors, chwibyok kans and morum kans. 3. In general, the surface treatments were subtle. Carved or inlayed ornamentation were seldom seen, and most chess were finished with clear lacquer to show the natural wood grain. There were no distinctive characteristics of surface ornamentation characteristic of any one type of chest. 4. The general patterns of the metal ornaments were spade(yowidu), round, bow, rectangular(yakgua), bat and flower shapes. The multi-level chests were decorated with more metal ornament types compared with the single-level chests. 5. In conclusion, there was more variety in all the design elements in the single level chests compared with the other types of chests. The bi-and tri-level chests were quite stylized in composition, size, proportion, surface treatment, and metal ornamentation.

• 헤리티지:역사와 과학
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• 제55권4호
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• pp.38-53
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• 2022

이 글에서는 삼국시대 토성을 중심으로 축조 기법과, 그 중에서도 판축기법을 둘러싼 개념과 용어를 정리, 검토해 보았다. 연구자별로 토성의 실체 및 축조 방법을 놓고 다양한 개념과 용어들을 사용하여 성격을 규정함으로써 혼란이 야기되고 있기 때문이다. 판축법은 성벽, 담장, 건물의 기단 등을 조성하기 위해 판으로 틀을 만들고 그 안에 흙이나 모래 등을 겹겹이 부어 공이 등으로 찧어서 견고하게 쌓아 올리는 전형적인 고대 토목기법 또는 건축 기법이다. 따라서 판축법으로 토성을 축조하였음을 입증하기 위해서는 성벽 내에서 판목(협판), 이를 고정하기 위한 기둥(고정주), 협판을 받치기 위한 횡장목과 종장목, 흙을 견고히 다진 달구질 흔적 등이 발견되어야 한다. 다만, 국내에서는 이와 같은 증거들이 온전히 발굴된 사례가 극히 적기 때문에 판축에 대한 기준을 얼마나 엄격히 적용할 것인지에 대해서도 합의가 필요한 실정이다. 토성 축조에 동원된 판축기법과 관련된 용어는 그 개념에 관한 용어를 필두로 판축 원리와 판축 단위, 그리고 구체적인 판축 기술과 관련된 용어로 구분하여 실제 사례를 통해 설명하였다. 특히 풍납토성에서는 고대 판축토성 축조에 이용된 전형적이고 다양한 기법들이 확인됨으로 해서 판축 기법의 원리와 기술을 이해할 수 있는 결정적인 자료들을 확보할 수 있었다. 향후 풍납토성 이외의 유적들에서 판축과 관련된 증거들이 더 많이 발견되어야 보다 보편적인 판축 기법의 이해가 가능할 것이다.