• Journal of Forest and Environmental Science
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• 제40권2호
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• pp.90-98
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• 2024

This study analyzes the characteristics of sound-absorbing materials made from forest by-products of the deciduous tree species Zelkova serrata (Z. serrata) by evaluating their sound absorption performance. Accordingly, sound-absorbing materials with varying sample thicknesses, leaf sizes, and drying conditions were fabricated. The sound absorption properties were measured using the impedance tube method via middle-type measurement tube (100 Hz-3,200 Hz). The sound absorption properties were evaluated using the average sound absorption coefficient (ASAC), which was calculated from the measured sound absorption coefficients at 250 Hz, 500 Hz, 1,000 Hz, and 2,000 Hz. The ASAC value significantly improved as the leaf size increased to 0.5×0.5 cm², 1.0×1.0 cm², and 2.0×2.0 cm². The ASAC values under the two drying conditions were similar. There was no significant difference in ASAC according to the leaf size under the air-dried leaf condition, with a thickness of 2.50 cm. The highest ASAC value according to the sound-absorbing material thickness was 0.47 at a thickness of 2.50 cm and leaf size of 2.0×2.0 cm² under the air-dried leaf condition. In addition, the variation in ASAC was 0.23, indicating that the sound absorption performance according to leaf thickness was more significant than the difference in absorption properties according to leaf size. A sound absorption coefficient (SAC) of 0.4 or higher was observed across the measurable frequency band (100 Hz-3,200 Hz). Furthermore, the SAC values with respect to leaf size and thickness were close to 1 in the high-frequency range above 2,000 Hz. Therefore, it is considered that sound-absorbing materials using Z. serrata leaves are advantageous in the field of absorbing noise in a high-frequency band of 2,000 Hz or more, and it is better to manufacture a thickness of 2.50 and 2.0×2.0 cm².

• 식물분류학회지
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• 제39권1호
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• pp.29-34
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• 2009

구절초 무리는 국내에 분포하는 국화속 중 흰색 또는 분홍색의 설상화를 가지는 특징으로 인해 다른 두 종과 구별되는데 외부형태학적 변이로 인하여 다양한 분류학적 견해가 제안되어 온 분류군이다. 본 연구에서는 지금까지 국화속의 종 및 종내 분류군을 인식하기 위해 이용되어 온 형태학적 형질 중 구절초 무리내의 종내 분류군을 인식하기 위한 특징의 일부로서 사용된 바 있는 잎의 두께에 주목하여 구절초 무리에 속하는 13개 집단과 근연종인 산국 및 감국의 4개 집단을 이용하여 잎의 구조적 특징을 확인하였다. 이를 위해 잎의 횡단절편을 제작하여 엽신의 두께와 세포층 수, 세포의 크기를 비교하였다. 잎의 두께를 확인해본 결과 산국, 감국, 구절초 무리 순으로 두꺼운 것으로 나타났으며 세 종 모두 9개 전후의 세포층으로 구성되어 있어 잎의 두께는 세포층 수가 아니라 세포 크기에 따라 달라지는 것으로 밝혀졌다. 구절초 무리 내에서는 집단 간에 잎의 형태 및 두께에서 다양한 변이를 보였는데 가는잎구절초, 바위구절초, 울릉구절초, 한라구절초 등 특히 제한적인 분포를 보이는 분류군들이 전국적인 분포를 보이는 분류군에 비해 상대적으로 두꺼운 잎을 가지는 것이 확인되었고, 이는 각 분류군이 고유의 서식환경에 적응한 결과로 생각된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.177-185
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• 2000

The characteristics of multi-leaf feil bearing are investigated. The Foil bearing is preloaded and has several leaf foils modeled by curved beams. An analysis of the air foil bearing was performed, considering effects of foil deflection and compressible lubrication equation simultaneously. A parametric study shows that the number of foils significantly affect the static characteristics of air foil bearings and describes what the minimum film thickness means. The results include pressure profile, load capacity, dimensionless torque and minimum film thickness in the foil bearing.

• 한국연초학회지
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• 제18권2호
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• pp.113-119
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• 1996

The ovipositional responses of two strains of the cigarette beetle, Lasioderma serricorne F., to thickness, of air- and flue-cured leaf tobacco were investigated. Eggs laid by the strains reared with wheatflour (95%) + yeast (5%) in the laboratory for several years were not different between air - and flue-cured tobacco leaves. There were negative correlations between grades of cured tobacco and ovipositional response, and the regression equation was Y(ovipositional response) : 58.22 - 10.15X(leaf grade). Adults of strains reared on tobacco leaves laid 161.00±80.29 eggs on the first grade of thick flue-cured leaves, and 7.67 ± 5.51 on the second grade of thin air-cured leaves. There was difference in ovipositional responses among different grades within variety, but significant differences were noted between thick and thin tobacco leaves. Key words : ovipositional response, cigarette beetle, Lasiodema sewicome F., tobacco.

• 한국연초학회지
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• 제3권1호
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• pp.66-74
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• 1981

This study was conducted to investigate the interaction between chemical compositions and agronomic characteristics of perique tobacco leaf. At the topping stage, the thickness of leaf was positively correlated with total sugar($\textrm{0.975}^{**}$), reducing sugar($\textrm{0.975}^{**}$), alkaloid($\textrm{0.518}^{*}$) and petroleum ether extract($\textrm{0.801}^{**}$) contents. The length of upper leaf was negatively correlated with its chemical contents. Total sugar contents of the harvested leaf showed a sigmoid pattern of distribution along the leaf stalk positions.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.335-335
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• 2017

Recently NERICA (New Rice for Africa) was developed by a crossing of African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.) in West Africa, and is considered to be drought resistant, but drought resistance of NERICA and differences between Asian rice are not clarified enough. In this research, NERICA (four cultivars and two lines), Asian rice (three cultivars and sativa parent of NERICA) and African rice (glaberrima parent of NERICA) were cultivated in the field in Shizuoka University under drought and traits of each cultivar and line relevant to drought resistance, stomatal conductance by porometer, soil water content of individual depths by TDR method, SPAD values by SPAD meter and leaf thickness by micrometer, were measured and compared with dry matter production and yield. Effects of compost were also compared among sativa parent, one NERICA cultivar and two NERICA lines. Glaberrima parent showed highest top dry weight. One NERICA line, one drought resistant Asian rice cultivar and sativa parent, showed higher top dry weight and yield (ear weight) than other Asian rice cultivars and NERICA cultivars and line tested. Compost tended to increase top dry weight and yield in one of NERICA line and sativa parent. But in one NERICA cultivar and line, top dry weight and yield were not increased. In one of Asian rice, one of NERICA line and sativa parent that showed high top dry weight and yield, stomatal conductance was high. On the contrary the glaberrima parent and in other NERICA cultivars and line it was low. In sativa parent compost increased stomatal conductance but in NERICA cultivar and lines it was not. Among cultivars and lines that showed high top dry weight and yield sativa parent and one of NERICA line SPAD value and leaf thickness were high but in one of Asian rice and glaberrima parent they were low. Cultivar and line differences in yield and top dry weight among Asian rice and NERICA were significantly correlated with those in stomatal conductance ($r=0.778^{**}$ and $r=0.654^*$, respectively) and those in leaf thickness ($r=0.600^*$ and $r=0.640^*$, respectively). In Asian rice cultivars average soil water content was significantly correlated with yield ($r=0.886^*$) but in NERICA cultivars and lines it was not significant correlated (r= -0.256). Cultivar and line differences in leaf thickness were significantly correlated with SPAD value ($r=0.773^{**}$). In Asian rice cultivars it was significantly correlated ($r=0.962^{**}$), but in NERICA cultivars and lines it was not significantly correlated (r=0.559). Asian rice cultivars tended to consume soil water to increase yield but in NERICA cultivars and lines the tendency was not clear. Correlation between SPAD value and leaf thickness was different between Asian rice and NERICA cultivars and lines, and in Asian rice cultivars it was significantly correlated but in NERICA cultivars and lines it was not significant. Importance of maintaining high stomatal conductance by high leaf thickness was clarified.

• Tribology and Lubricants
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• 제17권2호
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• pp.97-108
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• 2001

This paper describes the development of performance analysis technique for a leaf-type gas lubricated fail bearing. Stiffness coefficient and frictional damping due to the slip between all contacts of leaves are evaluated for various leaf structures. The fluid film thickness and pressure distribution are computed but it is not considered the elastic deformation by film pressure. The analysis results include the effects that the curvature radius and the length of leaf and the friction coefficient have on the static and dynamic characteristics of the foil bearings.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.229-235
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• 1996

The tapered leaf spring is regarded as the adequate tool to improve ride quality and to reduce vehicle weight of commercial vehicles. These effects are due to minimizing the contact area of each leaf by reducing the number of leaves and by optimizing the thickness profile of each leaf. But in adapting the tapered leaf spring to improve ride quality, we often have some problems of bad pitching and bouncing motion. This paper shows the basic properties of tapered leaf spring by rig tests and how to improve ride quality of a vehicle with tapered leaf springs, compared with multi-leaf spring. From the results of vehicle tests and rig tests it is concluded that the ride quality was effected by the dynamic spring rate and the friction of the tapered leaf spring.

• 한국작물학회지
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• 제48권3호
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• pp.248-251
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• 2003

콩의 입중에 따른 다수성 콩 품종육성의 엽형 모델을 찾고자 기존의 품종들을 대상으로 일의 형태 및 해부학적 특성과의 관계를 조사했는데. 그 결과를 요약하면 다음과 같다. 1. 엽신의 두께는 소립형 품종보다는 대립형 품종이 두꺼웠으며, 단위엽의 엽면적에서도 대립형 품종들이 큰 경향이었다. 2. 엽육조직의 관찰결과 소립 장엽형 품종과 대립 환엽형품종의 책상세포 및 해면세포가 두껍고 치밀하게 배열되어 있었다. 3. 단위엽면적당 $\textrm{CO}_2$ 흡수량, 주당 $\textrm{CO}_2$ 흡수량, 엽신 및 책상세포의 두께는 종실수량과 정의 상관이 인정되었으며, 단위엽의 엽면적과는 부의 상관을 보였다. 4. 따라서 품종간의 특성은 및 기능의 차이로서 인정할 수 있었으며 특히 $\textrm{CO}_2$ 동화량 및 엽육조직의 두께와 엽육세포의 치밀함 등은 품종간 특성차이를 나타내는데 크게 기여하였다.

• 한국환경과학회지
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• 제22권10호
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• pp.1345-1351
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• 2013

Leaf characteristics of two representative deciduous-tree species in Korean peninsula were compared to assess directional ridge effect on leaf traits of both species. Leaf mass per unit area (LMA) of Rhododendron schilippenbachii in south-facing ridge slope was significantly higher than that in north-facing ridge slope, while Quercus mongolica did not change LMA. Leaf mass of Q. mongolica was increased depending on leaf size irrespective of slope. However, leaf mass of R. schilippenbachii changed differently in responding to expansion of leaf area between both slopes resulting from retardation of leaf expansion in south-facing slope. R. schilippenbachii showed higher leaf nitrogen concentration per unit area (LNCA) in south-facing slope than that in north-facing slope, while Q. mongolica indicated no difference in LNCA between southand north-facing slopes. However, both species revealed no significant difference in leaf nitrogen concentration per unit mass (LNCM) between south- and north-facing slopes. LNCA of Q. mongolica was about two times higher than that of R. schilippenbachii. These results indicate that there is a difference in leaf characteristics including leaf thickness and nitrogen allocation between Q. mongolica and R. schilippenbachii, suggesting the difference of plasticity.