• Polymer(Korea)
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• v.31 no.3
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• pp.206-214
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• 2007

The theoretical study is developed for predicting the thermal expansion changes of composites which include complex inclusion, which is used three-dimensional ellipsoid model ($a_1>a_2>a_3$), which has two aspect ratios (the primary aspect ratio, $\rho_{\alpha}=a_1/a_3$ and the secondary aspect ratio, $\rho_{\beta}=a_1/a_2$). We can predict the feature of general thermal expansion factors by theoretical approach of matrix with aligned ellipsoidal inclusion using the Eshelby's equivalent tensor. The coefficients of longitudinal linear thermal expansion ${\alpha}_{11}$ decrease to those of inclusions, ${\alpha}_f$, as both aspect ratios increase. The coefficients of transverse linear thermal expansion of composites ${\alpha}_{33}$ initially increase and show the parabolic corves with maximum values, as the concentrations of filler increase. The coefficient of thermal expansion, ${\alpha}_{22}$ in the transverse direction decreases, as $\rho_{\alpha}$ increases, however, ${\alpha}_{22}$ increases as $\rho_{\beta}$ increases. The coefficient of linear thermal expansion of composites, ${\alpha}_{33}$ in the normal direction increases, as $\rho_{\alpha}$ increases, while ${\alpha}_{33}$ decreases as $\rho_{\beta}$ increases.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.141-155
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• 2018

Recently, the number of ground subsidence resulting from underground cavity has been increased. Accordingly, the importance of restoration of stress release zone around the underground cavity has been emphasized. The stress release zone is composed of low density soils having extremely low stiffness and degree of compaction, which can lead to additional cavity expansion and collapse of overlying ground. Therefore, in this study, the suitability of restoration method of underground cavity using expansive material for reinforcement of stress release zone around the cavity is verified. The basic physical properties and expansion characteristics of the expansive material were examined. The experiment equipment capable simulating of stress release zone was developed and is used to investigate the effect of expanding material on stress release zone. The stress release zone was simulated using the spring in numerical analysis. The factors of the volume ratio of the underground cavity to the expansion material, the degree of stress relaxation, and the shape of the cavity were varied in numerical simulations, and the behavior of stress release zone was analyzed based on the numerical analysis results. Analysis variables are factors that affect each other. Also, filling of underground cavity and capacity of restoration of stress release zone were confirmed when the expansive material was inserted into underground cavity.

• Journal of Gastric Cancer
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• v.4 no.4
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• pp.213-218
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• 2004

Purpose: The superficial spreading type of early gastric cancer has different clinicopathologic features from other types of early gastric cancer in terms of its invasiveness and lymph-node metastases. Therefore, we attempted to elucidate the pathological features, surgical procedures and patients prognoses. Materials and Methods: Clinical information was reviewed for patients who had undergone a gastrectomy for gastric cancer during an 8-year period ($1995\~2002$) at Dankook University Hospital and Ulsan University, with an average follow-up of 48 months. Three hundred (300) superficial spreading lesions were analyzed with respect to macroscopic type, lymph-node (LN) metastasis, recurrent pattern, survival rate and method of surgical operation. In addition, the clinicopathological features of the superficial spreading type were compared with those of 739 other patients with small-sized cancer. Results: In both groups, the IIc-type macroscopic lesion, the elevated subtype to be more specific, occurred most frequently. There was no significant difference in the method of surgery between the groups. The submucosal invasion was $39.8\%$ in small-sized cancer, and $61.7\%$ in superficial spreading cancer (P=0.005). The incidence of LN metastasis was $11.3\%$ in early gastric cancer, $7.8\%$ in small-sized cancer and $20.0\%$ in superficial spreading cancer (P=0.005). The incidence of lymphatic invasion was $4.6\%$ in small-sized cancer and $13.0\%$ in superficial spreading cancer (P=0.009). The incidence of recurrence was $1.4\%$ in small-sized cancer and $3.6\%$ in superficial spreading cancer. The overall 5-year survival rate was $84.8\%$ in superficial spreading cancer and $93.0\%$ in small-sized cancer (P=0.052). The 5-year diseasefree survival rate was $94.7\%$ in superficial spreading cancer and $87.5\%$ in small-sized cancer (P=0.053). Conclusion: The superficial spreading type of early gastric cancer tends to be more invasive and to show a higher incidence of lymph-node metastasis than small-sized early gastric cancer. A wide resection with extensive lymph-node dissection seems to be an appropriate treatment for a superficial spreading type of early gastric cancer.

• Journal of the Korean Geographical Society
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• v.26
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• pp.15-51
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• 1982

이 글에서는 다음의 내용을 다루었다. 1. 마산의 입지조건과 합포.마산포의 형성, (1) 마산의 입지조건, (2) 합포와 포산포의 형성 2. 신마산의 등장과 단일욱시의 성립, (1) 신마산의 등장, (2) 단일욱시의 성립 3. 마산의 인구팽창과 동마산의 성장, (1) 마산의 인구팽창, (2) 동마산의 성장, (3) 마산시의 입체경관(skyline)

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.24.2-24.2
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• 2005

• Landscaping Tree
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• v.80 no.5_6
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• pp.21-26
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• 2004

인류문명이 고도의 산업사회로 접어들면서 도시의 성장은 팽창을 거듭하여 더 많은 인구를 수용하고 더 넓은 면적을 차지하는 경향은 지금도 변함없이 진행되고 있다. 따라서 도시의 팽창은 그 만큼의 자연을 잠식하는 당연한 결과를 가져오고 인구 또한 생활터전을 찾아 도시로 집중하게 되어 자연과는 접할 수 있는 기회가 점점 멀어지고 있다. (중략)

• Journal of Industrial Technology
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• v.8
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• pp.71-80
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• 1988

높은 전압으로 충전된 Capacitor를 순간적으로 원통형 coil에 방전하면 순간적으로 강한 전자장 impulse가 발생한다. 이때 coil를 둘러 싼 금속 tube는 radial 방향의 힘을 얻어 팽창한다. 본 논문은 이때 tube내의 전자장분포와 tube 벽의 움직임을 integral equation method를 사용하여 해석하였다.

• The Science & Technology
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• v.33 no.7 s.374
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• pp.16-18
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• 2000

예산의 5%에 해당하는 4~5조원을 과학기술 분야에 투입하겠다는 정부의 발표는 고무적인 소식이다. 그러나 걱정이 되는 것은 급격한 팽창이 오히려 투자의 효과를 떨어뜨려 연구비 증대가 오히려 낭비로 끝나게 될 수도 있기 때문이다. 연구는 자발적이고 다양해야 하기 때문에 투자의 집중화를 막아야하겠고 또 대학이 좀 더 중요한 역할을 할 수 있도록 연구비의 물꼬를 대학으로 틀어주어야 하겠다.

• Journal of Korea Foundry Society
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• v.42 no.5
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• pp.307-313
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• 2022

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.803-810
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• 2007

An analytical method capable of predicting various stress-strain responses in axially loaded concrete confined with FRP (fiber reinforced polymers) composites in a rational manner is presented. Its underlying idea is that the volumetric expansion due to progressive microcracking in mechanically loaded concrete is an important measure of the extent of damage in the material microstructure, and can be utilized to estimate the load-carrying capacity of concrete by considering the corresponding accumulated damage. Following from this, an elastic modulus expressed as a function of area strain and concrete porosity, the energy-balance equation relating the dilating concrete to the confining device interactively, the varying confining pressure, and an incremental calculation algorithm are included in the solution procedure. The proposed method enables the evaluation of lateral strains consecutively according to the related mechanical model and the energy-balance equation, rather than using an empirically derived equation for Poisson's ratio or dilation rate as in other analytical methods. Several existing analytical methods that can predict the overall response were also examined and discussed, particularly focusing on the way of considering the volumetric expansion. The results predicted by the proposed and Samaan's bilinear equation models correlated with observed results with a reasonable degree, however it can be judged that the latter is not capable of predicting the response of lateral strains correctly due to incorporating the initial Poisson's ratio and the final converged dilation rate only. Further, the proposed method seems to have greater benefits in other applications by the use of the fundamental principles of mechanics.