• International Journal of Aeronautical and Space Sciences
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• 제6권2호
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• pp.33-45
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• 2005

The 1/9-scale model of a fighter-type configuration was tested in the Micro-Craft 8ft ${\times}$ 12ft wind tunnel facility. An abrupt lift dump was found at a certain range of angle of attack under the pre-scheduled approach configuration. To avoid a probable unsatisfactory flight behavior due to the lift dump, various aerodynamic devices were suggested. Extensive tests applying the cutoff leading edge flaps, boundary layer fences, saw tooth and vortex generators were performed with flow visualization as well as force and moment measurements. Test results showed that the origin of the lift dump was caused by the secondary boundary layer flow separation generated from the strong interaction between wing and flap. Various solutions for avoiding the unfavorable feature were suggested with the merits and demerits.

• Journal of Magnetics
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• 제16권3호
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• pp.216-219
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• 2011

Mn doped ZnO films were prepared on Si (100) substrates using sol-gel method. The prepared films were annealed at $550^{\circ}C$ for decomposition and oxidation of the precursors. XRD analysis revealed the presence of ZnMnO hexagonal wurtzite phase along with the presence of small quantity of $ZnMn_2O_3$ secondary phase and poor crystalline nature. The 2D, 3D views of magnetic domains and domain profiles were obtained using magnetic force microscopy at room temperature. Rectangular shaped domains with an average size of 4.16 nm were observed. Magnetic moment measurement as a function of magnetic field was measured using superconducting quantum interference device (SQUID) magnetometry at room temperature. The result showed the ferromagnetic hysteresis loop with a curie temperature higher than 300 K.

• 한국지구과학회지
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• 제34권5호
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• pp.381-392
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• 2013

Socheong island is a unique island containing Precambrian stromatolites in South Korea. Most of Socheong stromatolites are domes and columns, occurring as 10 cm to 1 m thick stromatolite beds. Lower parts of the stromatolite beds are predominantly composed of domes, but columns increase toward the upper level of stromatolite beds. In many of the stromatolite beds, inclined columns are easily identifiable, which is generally considered as a result of heliotropism. From general lithology, sedimentary structures, inclined angles and distributional pattern, and structural deformation of sedimentary rocks of Socheong island, the inclination of Socheong stromatolites could be better interpreted as a secondary structural deformation probably after formation of stromatolite columns, rather than as a result of heliotropism. However, at this moment, we do not clearly reject heliotropism interpretation for inclined columns of Socheong stromatolites. This is because the original position of stromatolite columns could have been lost if structural deformation had affected the whole sedimentary rocks of Socheong island.

• 한국작물학회지
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• 제14권
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• pp.111-115
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• 1973

대맥재배에 있어서 재식밀도와 시비량의 차이가 간의 형태적, 생리적 특성의 변화와 수량에 미치는 영향을 구명코저 시험한 결과를 요약하면 다음과 같다. (1) 시비량에 있어서는 표준시구보다 배비구에서 간 내, 외경, 간 벽후가 두꺼우며 단위간 건물중이 높고, 간장이 다소 커지며 수중, 수수가 많았다. (2) 재식밀도에 있어서는 소식일수록 도복에 견딜수 있는 방향으로 변화되었으나, 수량면을 고려하면 $5{\times}$5cm, $10{\times}$10cm 구가 알맞은 편이고 $15{\times}$15cm구와 $20{\times}$20cm구는 거의 비슷하였다. (3) 좌절하중, 좌절시 Bending moment, 단면2차 moment, 단면계수등은 표준비구보다 배비구가 높아 도복에 강하며, 재식밀도면에서는 소식일수록 전기형질의 수치가 높았다. (4) 도복지수는 밀식일 경우는 표준비구가 높으며 $10{\times}$10cm구 이상 소식일 때는 시비량과 재식거리에 따른 도복지수의 차이는 없었다. (5) 수량면에서는 배비가 좋으며, 안전다수를 위한 재식거리는 $5{\times}$5cm구가 가장 좋았다.

• 한국작물학회지
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• 제14권
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• pp.117-121
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• 1973

대맥의 생육시기별로 질소비료를 추비하여 맥체의 형태적, 물리적 특성에 미치는 영향을 검토코져 시험을 실시한 결과를 요약하면 다음과 같다. 1. 질소 추비에 따른 대맥의 형태적 특성변화의 추이를 보면, 도복과 관련이 깊은 형질, 중, 3월 추비구가 제 3-5절간장이 짧아지고, 지상부 생체중, 단위간 건물중이 많으며, 간 외경, 내경이 굵고 간 벽후가 두꺼워 내도복성인 소질을 보였다. 2. 생리적 특성변화의 추이를 보면, 저항성을 표시하는 좌절하중, 좌절시 Bending moment가 3월 추비구가 가장 높아 도복저항성이 강하였다. 3. 간의 만곡난이를 나타내는 단면계수, 단면 2차 moment등이 3월 추비구가 극히 높아 만곡이 되지 낳고 도복의 종합적인 표시방법인 도복지수가 낮아 도복의 저항성 및 강도가 가장 강하였다. 4. 3월 추비구는 수중이 높고 주당수량이 높아 적전추비기로 구명되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3068-3073
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• 2007

Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the performance study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and shadow graph. Numerical simulation was also performed to study flow characteristics and interactions between ramp tabs. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5464-5468
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• 2011

본 연구는 채혈바늘에 의해 발생하는 2차 감염을 방지하기 위한 안전 랜싯(Lancet)을 설계 개발하고, 연속하여 채혈하는 경우에 쉽게 그리고 편리하게 사용할 수 있도록 무선 전동방식 채혈기의 설계 제작을 목적으로 한다. 안전랜싯은 채혈침과 보호캡이 일체형으로 설계되어 채혈 순간을 제외하고는 채혈침이 항상 보호캡 속에 있도록 하여 채혈바늘에 의한 사고를 방지하도록 하였다. 전동 채혈기는 충전건전지를 전원으로 하고 솔레노이드의 작동으로 랜싯을 타격하여 채혈하도록 설계되었으며, 연발타격 또는 단발타격의 기능을 선택하도록 설계 제작되었다. 또한 타격봉에 의한 충격력과 사용된 배터리의 수명 등이 측정되었다. 이 채혈기는 한방병의원의 사혈기로도 사용되도록 제작되었다.

• 한국실내디자인학회논문집
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• 제17권4호
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• pp.92-101
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• 2008

A new paradigm of design lays stress on the world of metaphysical concepts, and various attempts are being made to give meaning to psychological values. Hotel is a memorable place to remind of a special moment in one's life such as travel, marriage, meeting and so on. It also contains even more symbolism than other spaces as it is the place where the most primary and private act takes place apart from one's residence. As a result, it is also possible to communicate the message which a designer intends to convey through the user's recognition in the form of various symbolic expressions in space design. The designer communicates a meaning into a space through a symbolic system and creates a mutual consensus by means of the understanding structure of "designer-space-user". The user's diverse interpretations through a symbol are based on epistemology and consist of the primary, the secondary and the tertiary recognition structure system in the aspect of their contents. The primary structure depends on sensual perception, impressive idea and transcendental recognition based on metaphysical and perceptional association. The secondary structure includes casualty, continuous deduction and rational(integral) recognition. Finally, the tertiary structure is sublimation to the transcendental mental world beyond the boundary of emotion and it is classified into fundamental recognition structure on an object and archetypical recognition structure on an ego. These characteristics can derive systematic understandings and diverse interpretations on the symbol from the space of a hotel through the frame of analysis based on the artistic form of monosemous, polysemous and multidimensional frameworks and symbols. The framework of this analysis includes all the cases, and various methods which haven't been attempted in practice are presented. Therefore this study is not just a simple analysis of space but rather it will serve as a methodological tool for design that allows for various attempts of symbolic design concepts in the recognition structure system.

• Imaging Science in Dentistry
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• 제53권2호
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• pp.109-115
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• 2023

Purpose: The aim of this study was to evaluate changes in the trabecular bone through texture analysis and compare the texture analysis characteristics of different areas in patients with medication-related osteonecrosis of the jaw (MRONJ). Materials and Methods: Cone-beam computed tomographic images of 16 patients diagnosed with MRONJ were used. In sagittal images, 3 regions were chosen: active osteonecrosis(AO); intermediate tissue (IT), which presented a zone of apparently healthy tissue adjacent to the AO area; and healthy bone tissue (HT) (control area). Texture analysis was performed evaluating 7 parameters: secondary angular momentum, contrast, correlation, sum of squares, inverse moment of difference, sum of entropies, and entropy. Data were analyzed using the Kruskal-Wallis test with a significance level of 5%. Results: Comparing the areas of AO, IT, and HT, significant differences (P<0.05) were observed. The IT and AO area images showed higher values for parameters such as contrast, entropy, and secondary angular momentum than the HT area, indicating greater disorder in these tissues. Conclusion: Through texture analysis, changes in the bone pattern could be observed in areas of osteonecrosis. The texture analysis demonstrated that areas visually identified and classified as IT still had necrotic tissue, thereby increasing the accuracy of delimiting the real extension of MRONJ.

• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.844-853
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• 2003

In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solutions are obtained for the equations of motion of the reciprocating mechanism and the time-dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and for the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the Gumbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism.