• Radiation Oncology Journal
• /
• 제7권1호
• /
• pp.45-50
• /
• 1989

From Feb.1985 to Feb.1988,76 patients with squamous cell carcinoma of the lung treated at the Department of Therapeutic Radiology in Kyungpook National University Hospital were available for the analysis of this study. All patients received radiation of 4000cGy-6600cGy with curative aim. The overall rate of complete response was 25.0% and partial response was 452.6% The complete and partial regression of tumor was 14.3% in patients treated with dose below 5000cGy and 84.1% in the group treated with dose above 5000cGy (p<0.01). The complete response was seen only in the group of patients received radiation at least 6000cGy. The patterns of failure were as follows. The rate of initial intrathoracic recurrence was 52.6% in patients with complete response. The overall rate of failure was 68.8%. Distant metastasis was found in 47.4% of patients. Bone, contralateral lung, and brain were common metastatic sites in decreasing order All of the distant metastases and 80% of local recurrences were found within the first year after treatment.

• 한국산학기술학회논문지
• /
• 제17권10호
• /
• pp.289-299
• /
• 2016

무기체계는 효율적인 전투준비태세를 갖추기 위해 개발단계의 신뢰성을 중요시하고 있다. 이미 제조업을 중심으로 다양한 분야에서 데이터 분석을 활용한 신뢰성 향상이 이루어지고 있다. 하지만 무기체계 개발단계는 보안의 중요성, 데이터의 부족 등으로 데이터 분석이 어려운 실정이다. 따라서 장기적인 무기체계 품질향상을 위해 전력화 이후의 장비 정보가 수집된 후속군수지원 데이터 분석을 수행하였다. 본 연구의 제안하는 방법론은 후속군수지원 데이터를 통해 목적변수인 고장발생기간을 중심으로 상관성 패턴을 파악하는 것이며, 절차는 다음과 같다. 첫 번째, 신뢰성에 영향을 미치는 주요 변수를 선택하고 고장발생기간을 중심으로 변수 간 상관성을 파악하였다. 두 번째, 범주형 데이터 특성을 갖는 데이터로부터 상관성 패턴을 파악하기 위해 대응분석 기법을 적용하여 분석을 수행하였다. 세 번째, 기여도와 표현력이 높은 범주들을 추출하고 시각화를 통해서 고장발생기간과 가장 관련이 높은 변수를 찾았다. 그리고 고장발생기간이 짧은 변수의 패턴을 선별하고 빈도분석을 통해서 신뢰성 저하 요인들을 파악하였다. 따라서 본 연구는 신무기 개발 시 신뢰성 저하 요인을 제거하여 군의 전투준비태세 강화에 도움이 될 것으로 기대한다.

• Advances in concrete construction
• /
• 제4권4호
• /
• pp.319-332
• /
• 2016

In most cases strengthening reinforced concrete columns exposed to high strain rate is to be expected especially within weak designed structures. A special type of loading is instantaneous loading. Rapid loading can be observed in structural columns exposed to axial loads (e.g., caused by the weight of the upper floors during a vertical earthquake and loads caused by damage and collapse of upper floors and pillars of bridges).Subsequently, this study examines the behavior of reinforced concrete columns under rapid loading so as to understand patterns of failure mechanism, failure capacity and strain rate using finite element code. And examines the behavior of reinforced concrete columns at different support conditions and various loading rate, where the concrete columns were reinforced using various counts of FRP (Fiber Reinforcement Polymer) layers with different lengths. The results were compared against other experimental outcomes and the CEB-FIP formula code for considering the dynamic strength increasing factor for concrete materials. This study reveals that the finite element behavior and failure mode, where the results show that the bearing capacity increased with increasing the loading rate. CFRP layers increased the bearing capacity by 20% and also increased the strain capacity by 50% through confining the concrete.

• Structural Engineering and Mechanics
• /
• 제74권3호
• /
• pp.407-423
• /
• 2020

The pre-peak cyclic shear mechanism of two-order asperity degradation of rock joints in the direct shear tests with static constant normal loads (CNL) are investigated using experimental and numerical methods. The laboratory testing rock specimens contains the idealized and regular two-order triangular-shaped asperities, which represent the specific geometrical conditions of natural and irregular waviness and unevenness of rock joint surfaces, in the pre-peak cyclic shear tests. Three different shear failure patterns of two-order triangular-shaped rock joints can be found in the experiments at constant horizontal shear velocity and various static constant normal loads in the direct and pre-peak cyclic shear tests. The discrete element method is adopted to simulate the pre-peak shear failure behaviors of rock joints with two-order triangular-shaped asperities. The rock joint interfaces are simulated using a modified smooth joint model, where microscopic scale slip surfaces are applied at contacts between discrete particles in the upper and lower rock blocks. Comparing the discrete numerical results with the experimental results, the microscopic bond particle model parameters are calibrated. Effects of cyclic shear loading amplitude, static constant normal loads and initial waviness asperity angles on the pre-peak cyclic shear failure behaviors of triangular-shaped rock joints are also numerically investigated.

• Earthquakes and Structures
• /
• 제20권4호
• /
• pp.417-430
• /
• 2021

Due to functional requirements, SRC column-RC beam abnormal joints with characteristics of strong beam weak column, variable column section, unequal beam height and staggered height exist in the Steel reinforced concrete (SRC) frame-bent main building structure of thermal power plant (TPP). This paper presents the experimental results of these abnormal joints through cyclic loading tests on five specimens with scaling factor of 1/5. The staggered height and whether adding H-shaped steel in beam or not were changing parameters of specimens. The failure patterns, bearing capacity, energy dissipation and ductile performance were analyzed. In addition, the stress mechanism of the abnormal joint was discussed based on the diagonal strut model. The research results showed that the abnormal exterior joints occurred shear failure and column end hinge flexural failure; reducing beam height through adding H-shaped steel in the beam of abnormal exterior joint could improve the crack resistance and ductility; the abnormal interior joints with different staggered heights occurred column ends flexural failure; the joint with larger staggered height had the higher bearing capacity and stiffness, but lower ductility. The concrete compression strut mechanism is still applicable to the abnormal joints in TPP, but it is affected by the abnormal characteristics.

• Computers and Concrete
• /
• 제19권1호
• /
• pp.99-110
• /
• 2017

In this paper, the effect of normal load on the failure mechanism of echelon joint has been studied using PFC2D. In the first step, calibration of PFC was undertaken with respect to the data obtained from experimental laboratory tests. Then, six different models consisting various echelon joint were prepared and tested under two low and high normal loads. Furthermore, validation of the simulated models were cross checked with the results of direct shear tests performed on non-persistent jointed physical models. The simulations demonstrated that failure patterns were mostly influenced by normal loading, while the shear strength was linked to failure mechanism. When ligament angle is less than $90^{\circ}$, the stable crack growth length is increased by increasing the normal loading. In this condition, fish eyes failure pattern occur in rock bridge. With higher ligament angles, the rock bridge was broken under high normal loading. Applying higher normal loading increases the number of fracture sets while dilation angle and mean orientations of fracture sets with respect to ligament direction will be decreased.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.282-285
• /
• 2006

This study is to examine bond strength of beam reinforced with GFRP rebar under 4-point bending test by adopting BRITISH STANDARD. The variables were made to have bonding length of 5times$(5d_b)$, 10times$(10d_b)$ and 15times$(15d_b)$ of the nominal diameter of GFRP rebar and were done to analyze the relationship between the bonding strength and the slip. In the result of the test, pull-out failure was dominant in the $5d_b$ and $10d_b$ specimen, both patterns of the pull-out failure and concrete splitting failure appeared in the $10d_b$. On the other hand, the $15d_b$ specimen showed only concrete splitting failure at the end of bonding length. Therefore, it was prove that available bonding length of the GFRP rebar under bending condition on static test is over $15d_b$ then farther research such as fatigue bending test, development of bonding model, FEM parameter study should be performed.

• Geomechanics and Engineering
• /
• 제35권4호
• /
• pp.333-366
• /
• 2023

Rock as a mass generally exhibits discontinuities, commonly witnessed in rock slopes and underground structures like tunnels, rock pillars etc. When these discontinuities experiences loading, a new crack emerges from them which later propagates to a macro scale level of failure. The failure pattern is often influenced by the nature of discontinuity, geometry and loading conditions. The study of crack growth in rocks, namely its initiation and propagation, plays an important role in defining the true strength of rock and corresponding failure patterns. Many researchers have considered the length of the discontinuity to be fully persistent on rock or rock-like specimens by both experimental and numerical methods. However, only during recent decades, there has been a substantial growth in research interest with non-persistent discontinuities where the crack growth and its propagation phenomenon were found to be much more complex than persistent ones. The non-persistence fractures surface is generally considered to be open and closed. Compared to open flaws, there is a difference in crack growth behaviour in closed or narrow flaws due to the effect of surface closure between them. The present paper reviews the literature that has contributed towards studying the crack growth behaviour and its failure characteristics on both open and narrow flaws subjected to uniaxial and biaxial compression loading conditions.

• Radiation Oncology Journal
• /
• 제32권2호
• /
• pp.63-69
• /
• 2014

Purpose: To find the applicability of adjuvant radiotherapy for extrahepatic bile duct cancer (EBDC), we analyzed the pattern of failure and evaluate prognostic factors of locoregional failure after curative resection without adjuvant treatment. Materials and Methods: In 97 patients with resected EBDC, the location of tumor was classified as proximal (n = 26) and distal (n = 71), using the junction of the cystic duct and common hepatic duct as the dividing point. Locoregional failure sites were categorized as follows: the hepatoduodenal ligament and tumor bed, the celiac artery and superior mesenteric artery, and other sites. Results: The median follow-up time was 29 months for surviving patients. Three-year locoregional progression-free survival, progression-free survival, and overall survival rates were 50%, 42%, and 52%, respectively. Regarding initial failures, 79% and 81% were locoregional failures in proximal and distal EBDC patients, respectively. The most common site was the hepatoduodenal ligament and tumor bed. In the multivariate analysis, perineural invasion was associated with poor locoregional progression-free survival (p = 0.023) and progression-free survival (p = 0.012); and elevated postoperative CA19-9 (${\geq}37U/mL$) did with poor locoregional progression-free survival (p = 0.002), progression-free survival (p < 0.001) and overall survival (p < 0.001). Conclusion: Both proximal and distal EBDC showed remarkable proportion of locoregional failure. Perineural invasion and elevated postoperative CA19-9 were risk factors of locoregional failure. In these patients with high risk of locoregional failure, adjuvant radiotherapy could be considered to improve locoregional control.

• 융합보안논문지
• /
• 제10권1호
• /
• pp.55-61
• /
• 2010

소프트웨어 제품을 개발하여 테스팅을 거친 후 사용자에게 인도하는 시기를 결정하는 일은 아주 실제적이고 흥미 있는 일이 된다. 이러한 문제를 소프트웨어 최적 방출시기라고 한다. 본 연구에서는 소프트웨어의 결함을 제거하거나 수정 작업 중에도 새로운 결함이 발생될 가능성이 있는 무한고장수를 가진 비동질적인 포아송 과정에 기초하고 고장간격 수명 시간의 형태에 따른 방출시간의 비교에 대하여 연구되었다. 소프트웨어 요구 신뢰도를 만족시키고 소프트웨어 개발및 유지 총비용을 최소화시키는 최적 소프트웨어 방출 정책이 된다. 본 논문의 수치적인 예에서는 모의실험 자료 즉, 강도함수가 일정한 경우, 증가하는 경우, 감소하는 경우를 적용하여 최적 방출시기를 추정하고 그 결과를 나열 하였다.