• 치과방사선
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• 제16권1호
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• pp.59-68
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• 1986

The purpose of this investigation was to locate the central plane of the image layer on the panoramic machine relative to a specific point on the machine. In the study of the central plane of the image layer of panoramic radiograph, using the Morrita Company PANEX-EC a series of 33 exposures were taken with the 4-5 experimental pins placed in the holes of the plastic model plate, then evaluated by human eye. The author analyzed the central plane of the image layer by Mitutoyo-A-221 and calculated horizontal and vertical magnification ratio in the central plane of the image layer determined experimentally. The results were as follows: 1. The location of the central plane of the image layer determined experimentally was to lateral, compared with manufactural central plane. 2. Horizontal magnification ratio in the central plane of the image layer determined experimentally was 9.25%. 3. Vertical magnification ratio in the central plane of the image layer determined experimentally was 9.17%.

• 천문학회지
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• 제34권1호
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• pp.47-57
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• 2001

In this paper we have reconstructed an armillary sphere based on the Method of an Armillary Sphere Making described in the Volume 1 of The Collection of Writings on the Scientific Instruments-Uigijipsol (儀器輯說, two volumes) edited in the 1850's by Nam Byong-Chul (南秉哲, 1817-1863) who was a famous Korean states-man-scientist. Nam achieved convenience and accuracy in the measurements of stellar positions in the manner of selective setting the equatorial, ecliptic and horizontal poles by adding a pole axis exchange ring called Jaigeukkwon (載極圈) between the Three Arrangers of Time and Four Displacements. We made use of 3-dimensional graphic software for modelling Nam's armillary sphere which consisted of five layers-eight rings. Results of simulation showed that the pole axis exchange ring functioned properly in setting the equatorial, ecliptic and horizontal coordinates simply by exchange of positions of specified holes on the ring. We ascertained that the invention of Jaigeukkwon solved inherent problems in the conventional Chinese armillary sphere in computation of real ecliptic coordinates. It was revealed that Nam Byong-Chul made great contributions in the East Asian history of armillary sphere making.

• 한국강구조학회 논문집
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• 제20권3호
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• pp.445-454
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• 2008

철골모멘트접합부에 관한 이전의 연구에 의하면 RHS 기둥과 기존의 스캘럽을 가진 접합부실험체의 변형능력은 매우 열등했고, 보단부의 응력집중은 보에서 기둥으로 전달되는 모멘트의 전달효율에 영향을 받는다는 사실을 실험이나 해석적으로 밝혔다. 본 연구는 보강된 RBS 접합부와 용접수평스티프너를 사용한 효고현남부지진 이전에 지어진 모멘트 접합부를 내진보강하는데 주안점을 두었다. 이러한 내진보강은 시공성과 경제성을 고려하여 보의 하부플랜지에만 실시하였다. 접합부의 내진보강방법을 발견하고 이를 향상시키기 위해서 비선형유한요소해석을 통해서 다양한 변수를 바탕으로 한 파라메타 연구를 실시하였다.

• 설비공학논문집
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• 제11권4호
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• pp.448-456
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• 1999

Variations of thickness and effective thermal conductivity of frost forming on the horizontal] cylinder with respect to time were measured under cross flow. The local heat flux around the cylinder was determined by measuring the radial temperature distribution in the cylinder having small holes drilled axially in which T-type thermocouples were inserted, then by using one dimensional cylindrical heat conduction equation. The thickness and the surface temperature of the frost layer around the cylinder were measured periodically while developing the frost. Each experiment was peformed by varying the Reynolds number, the temperature, and the humidity condition. Specially the dew point temperature of the most cases was below the freezing point. Experimental data showed that the frost layers on the front and the rear surface were thicker than those on the top and the bottom one which was near the separation point. The thickness and effective thermal conductivity of the frost layer were affected by inlet air velocity, temperature, and humidity. Moreover, the effective thermal conductivity and the effective thermal resistance increase with respect to time.

• 치과방사선
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• 제21권1호
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• pp.119-125
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• 1991

In the study of magnification of image in the focal trough of panoramic radiography, (Yoshida company Panoura - Eight - s), a series of 63 x-ray films were taken with the 8-19 metal pins placed in the holes of the plastic plate, measured and evaluated by 4 observes. The author analyzed the vertical and horizontal magnification rate in the corrected focal trough. Results were as follows: 1. For vertial measurements, magnification rates were minimum 10% maximum 36% and the magnification for image of medial side was larger than that of image of lateral side from image layer. 2. For horizontal measurements, magnification rates were minimum-14% maximum 46% and images of medial side from focal trough were magnified and images of lateral side from focal trough were retrenched. 3. When moved 10㎜ downward occlusal layer, interspace was somewhat narrow between the pins and upper sides of pins were horizontally magnified but images of the end parts of pins showed tapered form. 4. When moved 10㎜ downward from the occlusal layer, opposite images showed overlapping.

• 한국결정성장학회지
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• 제15권4호
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• pp.135-140
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• 2005

Thermal-fluid analysis was performed to understand the thermal behavior in the horizontal CVD reactor thereby to design a susceptor which has a uniform deposition rate during silicon EPI growing. Four different types of susceptor designs, standard (no hole susceptor), hole $\sharp$1 (240 mm), hole $\sharp$2 (150 mm) and hole $\sharp$3 (60 mm), were simulated by CFD (Computational Fluid Dynamics) tool. Temperature, gas flow, deposition rate and growth rate were calculated and analyzed. The degree of flatness of EPI wafer loaded on the susceptor was computed in terms of silicon growth rate. The simulation results show that the temperature and thermal distribution in the wafer are greatly dependent on inner diameter of hole susceptor and demonstrate that the introduction of hole in the susceptor can degrade wafer flatness. Maximum temperature difference appeared around holes. As the diameter of the hole decreases, flatness of the wafer becomes poor. Among the threes types of susceptors with the hole, optimal design which resulted a good uniform flatness ($5\%$) was obtained when using hole $\sharp$1.

• 한국안전학회지
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• 제28권4호
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• pp.58-65
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• 2013

Transportation and further expansion of social infrastructure was needed along the development of urbanization and population concentration. To use the underground space due to the lack of availability of land, it is inevitable to intersect between present structure and tunnel during construction. Soil grouting is one of the ground improvement methods to reinforce weak soil around the underground structures by injection of grouting liquid. Some of central columns of an upper structure are damaged during injection of grouting liquid by injection pressure. To investigate and improve the stability of the tunnel, three dimensional analysis are performed with full construction stages which includes the construction of present underpass, damaging columns of the underpass, reinforcing the columns by H-pile and shear walls, and excavation and construct tunnel. The arrangement of grouting holes such as curtain and horizontal type affects largely to the stability of upper structure and horizontal arrangement diminish the shear forces which is the cause of damage of central columns. The liquid injection type of reinforcement for tunnel is not recommended while the presence of upper structure with columns. Wall type reinforcing is utilize for permant support of upper structures which is affected by grouting injection pressure. H-pile is utilize for temporary support, but not for permanent since the sharing of shear forces is not much to shear wall during tunnel construction.

• Geomechanics and Engineering
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• 제36권6호
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• pp.527-543
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• 2024

In the implementation of most civil structures, especially underground, deep excavations with a vertical slope are required. Using flexible retaining walls is applied as one of the ways to stabilize vertical holes. Therefore, it is necessary to know the parameters affecting the performance of such walls in reducing their horizontal movement. In this research, by building a suitable laboratory model, the parameters of the amount of flexibility, the embedment depth of the wall, the type and number of tieback in the wall were investigated for 42 static laboratory models. The purpose of this research is to study the flexible retaining wall with helical tieback compared to simple tieback at different heights, which shows the best performance in terms of reducing horizontal displacement in proportion to increasing or decreasing flexibility. On the other hand, one of the parameters affecting the flexibility of the wall, which is its bending stiffness, was extracted by numerical software outputs and studied on the results such as relative flexibility, stiffness, safety and numerical stability of the wall.The results of this study show that among the parameters, in the first place, the effect of the type of tieback is inhibited and in the second place, the ratio of thickness to wall height is known as the most important parameter. the best performance for walls with the helical tiebacks in reducing their horizontal displacement can be economically, flexibly and stability assigned to a wall that tiebacks is in the range of H2/t to H4/t and its flexibility ratio is 2/3.

• 한국결정학회지
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• 제7권1호
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• pp.44-56
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• 1996

CuInTe2 다결정은 수평전기로에서 합성하고, CuInTe2 단결정은 수직 Bridgman 방법으로 성장하여 결정구조를 조사하고, Hall 효과를 30K에서 293K의 온도영역에서 측정하였다. CuInTe2 다결정 및 단결정은 정방정계였다. 다결정의 격자상수는 a=6.168Å, c=12.499Å 그리고 c/a=2.026이었고, 단결정의 격자상수는 a=6.186Å, c=12.453Å, 그리고 c/a=2.013이었다. CuInTe2 단결정의 성장면은 Laue 배면반사 사진으로부터 구하였으며 (112)면이었다. CuInTe2 단결정의 Hall 효과는 van der Pauw 방법으로 측정하였다. 상온에서 측정된 c축에 수직한 시료의 운반자농도 p는 2.14×1023holes/m3, 전기전도도 δ는 739.58Ω-1m-1 그리고 이동도 μ는 2.16×10 m2/V·s 이었다. c축에 평행한 시료의 운반자농도 p는 1.51×1023holes/m3, 전기전도도 σ는 717.55Ω-1m-1 그리고 이동도 μ는 2.97×10-2 m2/V·s이었다. c축에 수직 및 평행한 시료의 Hall계수가 양의 값이어서 CuInTe2 단결정은 p형 반도체임을 알 수 있었다.

• Applied Biological Chemistry
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• 제41권8호
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• pp.583-586
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• 1998

Porous ceramic cups are used for monitoring ion concentration in soil solutions in various time course and depth. A soil solution sampler was constructed in laboratory by inserting pliable perfluoroalkoxy(PFA) tubings into porous cup through holes in PVC rod segment which plugged top opening of the porous cup. The system was installed in drip irrigated soil in a vertical position, and nitrogen movement below the drip basin was monitored. To collect soil solution, vacuum in the cup was applied with a hand vacuum pump. The samples obtained were sufficient enough to run quantitative analyses for a number of chemicals. Nitrogen transformation and movement could be well defined, and the system seemed to be relevant to the other soil solution samplers in monitoring chemical movement in soil. Although this system has general deficiencies found in the other samplers using ceramic cup, it could be easily constructed at a low cost. Since the tubing was pliable, the cups could be installed in horizontal position, and this allows installations of the cups at more precise depth increments and also more precise samplings of soil solution at each depth.