• Radiation Oncology Journal
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• 제26권3호
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• pp.189-194
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• 2008

목 적: 본 연구팀은 사지에 발병한 카포시육종의 방사선치료를 위하여, 물볼루스를 사용할 수 있는 기구를 고안하였고, 쌀볼루스 사용시와 비교하여 유용성을 평가하고자 하였다. 대상 및 방법: 환자가 앙와위 자세에서 하지를 삽입 할 수 있는 폴리스틸렌 상자를 만들고 비닐 재질의 진공비닐을 집어 넣어 물이 누수 되지 않도록 결합하였으며, 진공비닐안에 하지와 물 사이의 공기를 없애기 위해 진공 밸브와 진공 펌프를 연결하여 공기를 제거하였다. 본 연구에서 제작한 물기반 볼루스의 선량 균질도를 비교 평가하기 위해 진공비닐에 하지 팬텀을 삽입한 후 폴리스틸렌 상자에 직접 쌀을 채운 경우, 비닐봉지에 쌀을 담아서 넣은 경우, 그리고 물을 직접 채운 경우에 대해 전산화단층촬영을 시행하였다. 방사선치료계획시스템을 사용하여 공기층의 부피에 의한 밀도의 변화를 분석하였다. 또한 선형가속기를 사용하여 전산화단층 모의치료기와 동일한 셋업에서 하지 팬텀에 필름을 감고, 열형광선량계 6개를 조사야 안에 균등하게 붙여서, 대향이문 조사하여 선량의 균질도 및 선량 값을 측정하였다. 결 과: 각 세 종류 실험의 밀도 측정결과 물볼루스를 기준으로 쌀을 직접 넣은 경우는 14% 감소했으며, 쌀을 비닐 봉지에 나누어 넣은 경우는 18% 감소하였다. 필름의 분석 결과 물볼루스가 쌀볼루스보다 균질도가 $4{\sim}4.4%$ 정도 우수한 것으로 나타났다. 열형광선량계 측정 평균값 분석결과 물볼루스를 기준으로 쌀을 직접 넣은 경우는 3.4% 증가했으며, 쌀을 비닐봉지에 나누어 넣은 경우는 4.3% 증가하였다. 결 론: 자체 제작한 물볼루스 기구는 육안으로 치료 조사야를 확인할 수 있어 셋업의 정확성을 높였으며, 진공 밸브와 진공 펌프를 사용하여 공기층을 감소시켜 치료의 정확성을 높이는 동시에 목적 종양에 균질도가 높은 선량을 부여 할 수 있는 좋은 방안이라 할 수 있다.

• 천문학회보
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• 제40권1호
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• pp.63.1-63.1
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• 2015

In this study, we determine coronal electron density distributions by analyzing DH type II radio observations based on the assumption: a DH type II radio burst is generated by the shock formed at a CME leading edge. For this, we consider 11 Wind/WAVES DH type II radio bursts (from 2000 to 2003 and from 2010 to 2012) associated with SOHO/LASCO limb CMEs using the following criteria: (1) the fundamental and second harmonic emission lanes are well identified; (2) its associated CME is clearly identified in the LASCO-C2 or C3 field of view at the time of type II observation. For these events, we determine the lowest frequencies of their fundamental emission lanes and the heights of their leading edges. Coronal electron density distributions are obtained by minimizing the root mean square error between the observed heights of CME leading edges and the heights of DH type II radio bursts from assumed electron density distributions. We find that the estimated coronal electron density distribution ranges from 2.5 to 10.2-fold Saito's coronal electron density models.

• 대한기계학회논문집
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• 제17권5호
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• pp.1150-1160
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• 1993

본 연구에서는 보압과정시 급속한 압력구배에 의한 관성항의 영향을 고려하기 위해 수정된 Hele-Shaw 모델과 압축열 발생항, 온도와 압력의 변화에 따른 수지의 밀 도 이완현상에 대한 모델의 도입 및 유한요소법을 이용한 수치해석적 방법을 제시하여 정확한 잔류압력을 구하고 성형조건 및 물성치에 따른 수지의 거동을 살펴보고자 한다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권1호
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• pp.57-73
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• 1999

Baroclinic hydraulic model experiments on the time-varying states of the flow pattern and water exchange in Sagami Bay were carried out based on quasi-steady state experiments on the flow pattern. For the model experiments, density changes as well as time changes in the volume transport of the upper layer were executed to investigate the flow response of the bay in the case of a sudden inflow of low density water and variable volume transport into the Sagami Bay. The results of the model experiments showed that when the volume transport was increased frontal eddies or frontal wave streamers from the Kuroshio Through Flow were transferred to the inner part of the bay along with cyclonic circulation in the bay. In addition, density boundary currents appeared and flowed along the eastern boundary of the bay. As the upper layer density decreased, frontal eddies, frontal streamers and coastal boundary density currents occurred and proceeded along the eastern boundary of the bay at a high speed.

• 대한기계학회논문집A
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• 제21권8호
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• pp.1241-1249
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• 1997

The problem of structural topology optimization can be relaxed and converted into the optimal density distribution problem. The optimal density distribution must be post-processed to get the real shape of the structure. The extracted shape can then be used for the next process, which is usually shape optmization based on the boundary movement method. In the practical point of view, it is very important to get the optimal density distribution from which the corresponding shape can easily be extracted. Among many other factors, the presence of checker-board patterns is a powerful barrier for the shape extraction job. The nature of checker-board patterns seems to be a numerical locking. In this paper, an efficient algorithm is presented to suppress the checker-board patterns. At each iteration, density is re-distributed after it is updated according to the optimization rule. The algorithm also results in the optimal density distribution whose corresponding shape has smooth boundary. Some examples are presented to show the performance of the density re-distribution algorithm. Checker-board patterns are successfully suppressed and the resulting shapes are considered very satisfactory.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2158-2167
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• 2018

This paper analyzed the magnetic field produced by the cylindrical stator coils of permanent magnet spherical motor (PMSM). The elliptic equations about the vector magnetic potential were given. Given that the eddy current effects are neglected, the magnet field of the PMSM is regarded as irrotational field, which can be calculated by scalar magnetic potential. The current density of cylindrical stator coil was proposed based on the definition of current density. The expression of current density of stator coil was obtained according to the double Fourier series decomposition and spherical harmonic functions. Then the magnetic flux density for scalar magnetic potential was derived. Further, the influence of different parameters on radial flux density was also analyzed. Finally, the results by the analytical method in this paper were validated by finite element analysis (FEA).

• Journal of the Korean Wood Science and Technology
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• 제17권4호
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• pp.77-82
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• 1989

In this study the oxygen index method was used to compare the duration of flaming and the rate of weight loss at the level of 6 and 9mm panel thicknesses among solid wood, plywood, particleboard, and medium density fiberboard. The obtained results were as follows: 1. In 9mm-thick panels, the combustibility was the largest in lauan solid wood followed by medium density fiberboard. particleboard. and plywood. 2. Medium density fiberboard was burned more easily than plywood in 6mm-thick panels and the higher oxygen concentration was needed as the panel thickness increased. 3. The oxygen indices of 9mm-thick panels were 29.0 in lauan solid wood, 31.4 in medium density fiberboard, 33.0 in particleboard, and 33.4 in plywood and those of 6mm-thick panels were 28.3 in medium density fiberboard and 29.7 in plywood. 4. The rate of weight loss was the largest in lauan solid wood followed by medium density fiberboard, plywood, and particleboard.

• Journal of Ginseng Research
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• 제22권2호
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• pp.96-101
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• 1998

This paper describes the determination of bulk density and the discrimination of internal structure of red ginseng by nuclear magnetic resonance (NMR). The 102 red ginseng roots were tested for bulk density. The NMR properties measured by NMR parameters such as spin-lattice relaxation time ($T_1$) and spin-spin relaxation time ($T_2$) were determined using the low field proton NMR analyzer. Bulk density of red ginseng root showed a highly negative significant correlation (r=-0.8934) with the value of $T_1$, but a highly positive significant correlation (r=0.7672 and 0.5909) with the value of T21 (short T2) and T22 (long T2), respectively. Multiple regression equation, Y=-0.0069.$T_1$+0.3044.$T_{21}$-0.0156.$T_{22}$-0.6368, using the MNR parameter values of 80 red ginseng roots can effectively predict the bulk density of 22 red ginseng roots with the correlation coefficient of 0.9396 and the standard error of 0.086. The differences in the internal structure of normal and inside white part of red ginseng were easily found by the signal intensity of NMR image based on magnetic properties of proton nucleus.

• 한국초전도ㆍ저온공학회논문지
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• 제21권4호
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• pp.29-33
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• 2019

2G HTS wire with high engineering current density is desired for applications where compact, high power density superconducting equipment is important. We have succeeded in enhancing engineering current density of commercial SuperOx 2G HTS wire based on GdBCO by increasing the HTS layer thickness without fast degradation of the HTS film microstructure. This was possible after improving the temperature uniformity along the HTS film deposition zone. In particular, the wire engineering current density was increased from 700-770 A/㎟ (for a 65 ㎛-thick wire without stabilisation) or 430-480 A/㎟ (for a 105 ㎛-thick stabilised wire) at the beginning of this study to almost 1200 A/㎟ (for a 67 ㎛-thick wire without stabilisation) or 770 A/㎟ (for a 107 ㎛-thick stabilised wire) at completion of this study.

• Journal of Electrochemical Science and Technology
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• 제4권1호
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• pp.27-33
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• 2013

The consequences of electrode density and thickness for electrochemical performance of lithium-ion cells are investigated using 2032-type coin half cells. While the cathode composition is maintained by 90:5:5 (wt.%) with $LiCoO_2$ active material, Super-P electric conductor and polyvinylidene fluoride polymeric binder, its density and thickness are independently controlled to 20, 35, 50 um and 1.5, 2.0, 2.5, 3.0, 3.5 g $cm^{-3}$, respectively, which are based on commercial lithium-ion battery cathode system. As the cathode thickness is increased in all densities, the rate capability and cycle life of lithium-ion cells become significantly worse. On the other hand, even though the cathode density shows similar behavior, its effect is not as high as the thickness in our experimental range. This trend is also investigated by cross-sectional morphology, porosity and electric conductivity of cathodes with different densities and thicknesses. This work suggests that the electrode density and thickness should be chosen properly and mentioned in detail in any kinds of research works.