• 한국유기농업학회지
• /
• 제3권1호
• /
• pp.71-78
• /
• 1994

This experiment was conducted to investigate the effects of mixed application of earthworm cast and N-fertilizer on dry matter(DM) yield in orchardgrass(Dactylis glomerate L.). Experimental plot were designed by a randomized block design with 3 replications of six different treatments-Control(0:0), 100% earthworm cast(0:100), 3 levels of mixed application(25:75:, 50:50, 75:25) of earthworm cast and N-fertilizer, and 100% N-fertilizer(100:0)based on content (%) of nitrogen. The experiment was carried out from March to October, 1993, on the forage experimental field of Kon-Kuk Univ. in Seoul. The results obtained are summarized as follows: 1. Annual dry matter yield was significantly increased according to increasing of N-fertilizer 2. Dry matter yield for each treatment as cutting time was passing was decreased. However, dry matter yield was slightly increased at 75%, 50%, and 25% mixed application of earthworm cast at the third cutting time than the second cutting time(p<0.05). 3. concerning each treatment per cutting time, dry matter yield was higher at 100% N fertilizer than the other treatments at the first, second, and fourth cutting time except the third cutting time only(p<0.05). And according to decreasing of mixing ratio of N fertilizer, dry matter yield was decreased, too. 4. Dry matter yield of 100% earthworm cast was significantly higher than control at the fourth cutting time(p<0.05).

• 한국표면공학회지
• /
• 제20권4호
• /
• pp.144-153
• /
• 1987

In the case of dipping the Ni-Resist cast iron into molten aluminum with iron content, the thickness of intermetallic compound was remarkably increased with increasing iron content. The thickness was shown by following equation in the range of 1-3% iron content; $x=22.5t^{1/2}+4.47{\cdot}t{\cdot}(Fe%)$. where, x is thickness(${\mu}m$), t the time (minute), Fe% the iron w/o. When the Ni-Resist cast iron was dipped into the molten aluminum containing zinc content, the intermetallic compound thickness was also increased with increasing zinc contents. And thickness was represented by the following equation in the range of 2-10% zinc content; $x=3.46t^{1/2}+0.27{\cdot}t{\cdot}(Zn%)$. However, in the case of dipping the Ni-resist cast iron into molten aluminum with silicon content, the thickness of intermetallic compound was decreased with increasing silicon content, as shown in the following equation; $x=7.17t^{1/2}-0.15{\cdot}t{\cdot}(Si%)$. The intermetallic compound formed onto Ni-Resist cast iron was identified to be $FeAl_3\;and\;Fe_3Al$. As the result of hardness measurement, the peak hardness appeared in the intermetallic compound at near interface of the cast iron and the compound.

• Structural Engineering and Mechanics
• /
• 제19권2호
• /
• pp.173-184
• /
• 2005

For reducing construction cost, two-plate-girder bridges are getting popular in Japan. This type of bridge employs a PC slab, which is often cast-in-place. In such a case, concrete is not usually cast over the whole slab at one time: some portions are constructed earlier than the rest. Therefore, a construction joint is inevitably created. Due to the drying shrinkage of concrete, tension stress may occur in concrete slab. High tensile stress can be expected near the construction joint where concretes with different ages meet. Moreover, prestressing is not applied over the whole length of slab at one time. This may also serve as a source of tensile stress in the slab. Thus there is a chance that cast-in-place PC slab, especially near the construction joint, may be subjected to tensile cracking. In the present study, stress states near the construction joint in the cast-in-place PC slab of a two-plate-girder bridge are investigated numerically. The finite element method is employed and the three-dimensional analysis is conducted to see the influence of dry shrinkage and prestressing. The stress states in the PC slab thus obtained are discussed. The simplified model of a plate girder for this class of analysis is also proposed.

• 한국재료학회지
• /
• 제31권8호
• /
• pp.433-438
• /
• 2021

In this study, microstructural characteristics and constituent elements of fiberglass splint and cast are examined using a scanning electron microscope and an energy dispersive X-ray spectrometer. As observed by the scanning electron microscope, fiberglass splint and cast had a porous structure with many bundles of fiberglass textures well assembled. Spaces between bundles of the fiberglass splint are triangular or elliptical shaped and the long-axis diameter is measured at about 1 mm. The thickness of fiber bundles covered with plaster is measured at 600 ㎛ and the diameter of a single strand of fiberglass is up to 10 ㎛. The thickness of the fiberglass bundle of the fiberglass splint is measured at about 700 ㎛. Spaces between bundles are formed in the shape of triangles with gentle edges and long-axis diameter of up to 1.4 mm, which is larger than that of the splint. The thickness of a single strand of fiberglass of the plaster-coated cast is 11.5 ㎛, which is thicker than that of fiberglass of the splint. As a result of analyzing constituent elements of the fiberglass cast and the splint with an energy dispersive X-ray spectrometer, Ca, Si, and Al components are identically detected. This result shows that the fiberglass cast has a smoother surface with hardened plaster than the fiberglass splint. The thickness of the fiberglass bundle and the thickness of a single strand of the fiberglass are also larger than those of the fiberglass splint.

• 대한간호학회지
• /
• 제24권4호
• /
• pp.517-528
• /
• 1994

The purpose of this study was to compare the circumference, skinfold thickness and strength of the normal and casted lower limb prior to casting and following removal of the cast. The subjects for the study were nine orthopedic patients who had had long and short leg casts due to a tibial, fibula, or calcaneus fracture, or to a lateral collateral ligament rupture. Circumference, skinfold thickness, and strength of the normal and casted lower limb following removal of the cast were compared with those prior to the application of the cast. Measurements were made before cast application and after removal of the cast. Skinfold thickness was measured by fat caliper, circumference was measured by tape and strength was determined by measuring the length of time the leg was held elevated at 45$^{\circ}$. The results can be summarized as follows 1. There was no change in the normal limb in the circumference of the midthigh and midcalf after casting as compared to before cast application. 2. In the casted limb the circumference of the midthigh decreased by 3.23% and that of the midcalf decreased significantly by 7.49% during the period of casting. 3. In the normal limb skinfold thickness of the quadriceps decreased and that of gastrocnemius increased by 20.63% during the period of cast application. 4. In the casted limb skinfold thickness of the quadriceps decreased significantly by 12.37% and that of gastrocnemius decreased by 10% during the period of cast application. 5. Strength of the normal lower extremity decreased significantly by 48.37% and that of casted lower extremity decreased remarkably by 73.07% during the period of cast application. 6. Circumference of the midthigh and the midcalf decreased significantly by 7.6% and 9.4% respectively on the casted side as compared to the normal side. Skinfold thickness of the quadriceps and the gastrocnemius on the casted side decreased by 6.12% and 18.55% respectively as compared to the normal side and strength in the lower extremity on the casted side decreased significantly by 44.32% as compared to the nor-mal side. From these results, it may be concluded that muscle atrophy occurs in the casted lower limb and muscle strength of the normal lower limb are also reduced during the period of application of a leg cast.

• 유기물자원화
• /
• 제2권1호
• /
• pp.65-73
• /
• 1994

본 연구는 지렁이 분립의 혼합비율이 고추 플러그묘의 생육에 미치는 효과를 조사하기 위하여 수행되었다. 본 연구에서는 지렁이의 분립은 20,30,40,50%로 투입하고 나머지는 peatmoss와 vermiculite로 보충하여 배합하였다. 얻어진 결과는 다음과 같다. 1. 엽수, 엽면적, 건물수량등에서 차이가 있었으며 (0.1%의 통계적 유리성), 지렁이 분립의 혼합비율에 있어서는 엽수, 엽면적 및 경중에서 1%와 엽중, 근중 및 생물학적 건물수량에서는 5%의 유의성이 인정되었다. 2. 지렁이 분립을 혼합한 상토가 국내 시판중인 상토 보다 조사후기에 접어들수록 많은 엽수와 엽면적의 증거를 나타내었다. 3. 지렁이 분립을 처리한 상토에서 대조구보다 전 육묘기간을 통해 엽중, 경중 및 근중 등이 전반적으로 높았는데, 이러한 경향은 지렁이 분립의 비율이 40% 이상에서 현저하였다. 4. 조사시작 후 3주째까지는 엽중이 경중보다 높았지만 4주째 부터는 경중이 더 높았으며, 또한 육묘후기에는 지렁이 분립을 혼합한 처리에서 대조구 보다 경중이 더 높았다. 5. 생물학적 건물수량은 조사초기에는 처리간 차이가 없었으나 후기에는 지렁이 분립을 혼합한 처리구가 대조구 보다 높았다.

• 한국산학기술학회논문지
• /
• 제21권12호
• /
• pp.434-439
• /
• 2020

최근, 치과 산업에서 레이저를 열원으로 합금을 제조하는 선택적 레이저 용융법(Selective laser melting, SLM)이 소개되고 있다. 하지만 SLM으로 제작된 금속-세라믹 수복물에 대한 연구가 부족한 실정이다. 따라서 본 연구의 목적은 SLM 그리고 CAST(casting)에 의해 제조된 Co-Cr 합금의 금속-세라믹(metal-ceramic) 결합 강도(bond strength)를 평가하는 것이다. SLM 그리고 CAST 방법을 사용하여 Co-Cr 시편을 제조하고 세라믹을 소결하여 시료를 제작하였다. 연구의 실험은 표본 준비 및 분석을 통해 2020년 1월부터 6월까지 수행되었다. 금속-세라믹 결합 강도는 만능 시험기에 의해 측정되었다. 부착 세라믹의 면적분(The area fraction of adherence ceramic, AFAC)은 SEM/EDS로 시편의 Si 함량을 측정하였다. 금속-세라믹 결합 강도 및 AFAC 결과는 t-test를 사용하여 분석하였다(α = .05). SLM 그리고 CAST Co-Cr 합금 사이의 결합 강도에 대해서는 유의한 차이가 발견되지 않았다(P>.05). SLM은 CAST 그룹보다 많은 세라믹 부착성(ceramic adherence)을 나타냈다(P<.001). 세라믹과 합금의 결합 강도는 제조 방법엥 영향을 받지 않았다. 그러나 SLM은 더 우수한 세라믹 부착성을 보였다. 이는 향후 임플란트 상부 보철물 제작에도 SLM으로 제작한 합금이 사용 가능한 것을 시사한다. CAST 방식의 단점을 극복하고 시간과 비용을 절약할 수 있을 것으로 기대된다.

• 한국재료학회지
• /
• 제7권4호
• /
• pp.310-316
• /
• 1997

The effects of carbide and matrix structures on the abrasion wear resistance of multi-component white cast irons with 3.0 mass%C have been studied in this paper. Four different heats were poured in order to obtain the specimens with different combinations of the carbide structures: a basic iron(3.0 mass%C-5.0 mass%Cr-5.0 mass%V-5.0 mass% Mo-12.5mass%W)for M$_{6}$C and M$_{7}$C$_{3}$ carbides, and a Cr free iron(3.0 mass%C-5.0 mass%V-2.5mass%Mo-12.5 mass%W) for MC and M6C carbides. A conventional high Cr free free iron(3.0 mass%C-5.0 mass%V-2.5 mass%Mo-12.5 mass%W) for MC and M6C carbides. A conventional high Cr white cast iron was also poured to compare its wear resistance with those of the multi-component white cast irons. In the as-cast condition, the range of abrasive wear rate(Rw=mg/min) was from 4.15 to 5.98 . The lowest Rw, which means the highest wear resistance, was obtained in the basic iron with nodular MC, lamellar M$_{2}$C and cellular M$_{7}$C$_{3}$ carbides. On the other hand, the Rw of the high Cr white cast iron ranked between the basic iron and the Mo and W free iron. In each alloy, the Rw of air hardened or tempered specimen was lower than that of the as-cast one because of the change of matrix structures by the heat treatments. The Rw of the hear treated speci-mens increased in the order Mo and W free iron, basic iron, Cr free iron, high Cr iron, and V free iron.n.n.n.

• 한국주조공학회지
• /
• 제10권4호
• /
• pp.299-308
• /
• 1990

Ductile cast iron has a good ductility and ductility and toughness than those of gray cast iron, because the shape of graphite is spheroidal. It has been reported that the strengthening and toughening of the ductile cast iron was resulted from the good modification of various matrix structures obtained by the heat treatment or addition of alloying elements. This study aims to investigate the effect of various special heat treatment(Cyclic Heat Treatment, Intermediate Heat Treatment, Step Quenching), austempering and alloying element(Ni) on the strength and toughness of ductile cast iron. The results obtained from this study are summarized as follows. 1) With addition of Ni, the amount of pearlite or bainite were increased and the morphologies of pearlite or bainite became finer by special heat treatments. 2) As the Ni added and not added ductile cast iron were treated by austenitizing at $900^{\circ}C$ and $840^{\circ}C$, in the latter the austenite was mostly formed in the vicinity of eutectic cell boundary, but in the former on the whole matrix. 3) In cyclic heat treatment, the volume fraction of pearlite was increased and the shape of pearlite was fined with increase of the number of cycle. 4) The shape of pearlite was mostly bar type in the intermediate heat treatment, but spheroidal type in step quenching. 5) The mechanical properties of ductile cast iron containing 1.5%Ni austempered at $400^{\circ}C$ for 25min. after austenitizing at $900^{\circ}C$ for 15min. were a good value of hardness 105(HRB), impact energy 12.5(kg.m), tensile strength 112($kg/mm^2$) and elongation 6.8(%).

• The Korean Journal of Physiology and Pharmacology
• /
• 제13권6호
• /
• pp.491-496
• /
• 2009

Skeletal muscle atrophy is a common phenomenon during the prolonged muscle disuse caused by cast immobilization, extended aging states, bed rest, space flight, or other factors. However, the cellular mechanisms of the atrophic process are poorly understood. In this study, we investigated the involvement of mitogen-activated protein kinase (MAPK) in the expression of muscle-specific RING finger 1 (MuRF1) during atrophy of the rat gastrocnemius muscle. Histological analysis revealed that cast immobilization induced the atrophy of the gastrocnemius muscle, with diminution of muscle weight and cross-sectional area after 14 days. Cast immobilization significantly elevated the expression of MuRF1 and the phosphorylation of p38 MAPK. The starvation of L6 rat skeletal myoblasts under serum-free conditions induced the phosphorylation of p38 MAPK and the characteristics typical of cast-immobilized gastrocnemius muscle. The expression of MuRF1 was also elevated in serum-starved L6 myoblasts, but was significantly attenuated by SB203580, an inhibitor of p38 MAPK. Changes in the sizes of L6 myoblasts in response to starvation were also reversed by their transfection with MuRF1 small interfering RNA or treatment with SB203580. From these results, we suggest that the expression of MuRF1 in cast-immobilized atrophy is regulated by p38 MAPK in rat gastrocnemius muscles.