• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.209-217
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• 1991

We have carried out a preliminary study to search for the new fracture mechanics parameter which can effectively estimate the fatigue life. In this study, the distribution of local fatigue strains near a fatigue crack tip was detailedly revealed using by fine dot grid strain measurement method. From these results, a single parameter (.DELTA.A), which characterize local fatigue strain field, was nearly proposed by the authors.

• Journal of Ocean Engineering and Technology
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• v.5 no.2
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• pp.76-84
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• 1991

본 연구는 피로수명 평가를 위한 새로운 파괴역학적 parameter의 확립에 관한 연구이다. 실질적으로 피로파괴가 일어나는 피로 균열선단의 국소영역에서 변형분포를 미소원형격자측정법을 이용하여 실험적으로 명확히 밝혀내었다. 그리고 이 결과를 기초로 하여 국소피로 변형율장을 대표할 수 있는 피로변형율 확대계수 $\Delta$A를 제안하였다. 또한 새로운 parameter $\Delta$A의 유효성을 여러 피로조건에서 검토한 결과, 균열선단 국소 영역에서 피로 변형율 확대계수 $\Delta$A에 의하여 피로 균열전파 속도평가를 일의적으로 나타낼 수 있음을 확인하였다.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.339-353
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• 1998

In this paper, the previous damage models for structures and their components under seismic repeated loading were reviewed systematically. A failure criterion for steel members under severe cyclic excitations as in strong earthquakes was described. A new approach to seismic damage assessment for steel members was proposed. This method was based on a series of the experimental and numerical investigations for steel members under very low cyclic loading. In this study, very low cyclic loading means repetitive loading, 5 to 20 loading cycles, within the large plastic range. The proposed damage assessment method was focused on the local strain history at the cross-section of the most severe concentration of deformation.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.613-625
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• 2002

This paper aimed to investigate the damage process of steel parts experiencing failure under strong repeated loading. Likewise, a damage index using various factors related to the damage was proposed. An analysis method for evaluating the damage state was also developed. The damage assessment method focused on the local strain history at the cross-section of the heaviest concentration of deformation. Cantilever-type steel parts were analyzed under uniaxial load combined with a constant axial load, considering horizontal displacement history, Loading patterns and steel types were considered as the main parameters in analyzing the models. The effects of the parameters on the failure modes, deformation capacity, and damage process as seen from the analysis results were also discussed. Each failure process was compared as steel types. In addition, the failure of steel parts under strong repeated loading was determined according to loading. Results revealed that the state of the failure is closely related to the local plastic strain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.703-710
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• 1994

A nonlinear FEM analysis of steel members under very-low-cycle loading has been performed in conjunction with experimental works. This analysis is an FEM tracing toward cracking of steel members under cyclic loads such as a strong earthquake. After verifying the procedure by comparing global hysteretic behaviors from the analytical and experimental results, the local stress-strain hysteresis at critical sections for large cyclic deformations was traced by the numerical analysis. Local strain history was discussed in relation to cracking. Based on the experimental and analytical results, a new approach to seismic safety assessment for steel members was proposed in this paper.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.312-318
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• 2001

Purpose : To assess the locoregional recurrence rate, survival rate and prognostic factors after modified radical mastectomy and postoperative adjuvant radiation therapy with or with chemotherapy in high-risk breast cancer patients. Methods : Between $1984\~1995$, 48 patients underwent postoperative irradiation to the regional lymphatics and chest wall due to large tumor size $(\geq5\;cm)$ or small tumor size (<5 cm) with axillary lymph node involvement after modified radical mastectomy. The median age of the patients was 47 years (range, $31\~79\;years$). The clinical tumor size was <2 cm in 1 patient, $2\~5\;cm$ in 15 patients, and >5 cm in 32 patients. Thirty two patients had positive axillary lymph nodes. Forty two patients were irradiated to the chest wall and regional lymph node and 6 patients were irradiated in the chest wall only. Radiation dose to the chest wall and regional lymph node was 5040 cGy/28 fraction. The median follow-up time was 61 months. Results : Locoregional recurrence rate was $8\%$ and distant metastatic rate was $14\%$. The actuarial overall survival rate and disease-free survival rate was $53\%\;and\;62\%$ at 5 years, respectively. The median survival time was 57 months. Five-year overall survival rate by the stage is $70\%$ in IIB and $58\%$ in IIA. The significant prognostic factor for survival on multivariate analysis was the stage. Conclusion : Postoperative adjuvant radiation therapy in high-risk breast cancer can reduce the locoregional recurrence rate and increase the survival time by combined chemotherapy. The significant prognostic factor for survival rate was the stage.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.158-166
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• 2002

In this paper, we proposed a contour shape description method which use the CFR(contour fluctuation ratio) feature. The CFR is the ratio of the line length to the curve length of a contour segment. The line length means the distance of two end points on a contour segment, and the curve length means the sum of distance of all adjacent two points on a contour segment. We should acquire rotation and scale invariant contour segments because each CFR is computed from contour segments. By using the interleaved contour segment of which length is proportion to the entire contour length and which is generated from all the points on contour, we could acquire rotation and scale invariant contour segments. The CFR can describes the local or global feature of contour shape according to the unit length of contour segment. Therefore we describe the shape of objects with the feature vector which represents the distribution of CFRs, and calculate the similarity by comparing the feature vector of corresponding unit length segments. We implemented the proposed method and experimented with rotated and scaled 165 fish images of fifteen types. The experimental result shows that the proposed method is not only invariant to rotation and scale but also superior to NCCH and TRP method in the clustering power.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.636-642
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• 1989

In this paper, 3-dimensional fracture phenomena in the local area near the notch tip between the surface and the center of a composite bar which is consisted of two different materials were investigated by using embedded dyeing grids with the pitch of 50.8.mu. It was confirmed that the maximum strain near the notch tip occurred not at the notch front but at the curvature beginning point of the notch which is in the interior of z/W = 0.3 - 0.35 from the surface and a notch was initiated from that point. And that the strain near the notch front between the center and z/W = 0.65 - 0.7 toward the surface was in a state of compression.

• Radiation Oncology Journal
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• v.22 no.1
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• pp.17-24
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• 2004

Purpose: To evaluate the treatment outcomes after postmastectomy radiotherapy (PMRT) and chemotherapy in patients with breast cancer. Materials and Methods: The PMRT were retrospectively analyzed in 83 patients with stage II-III female breast cancer treated between 1989 and 1995. The median age was 46 years (range, 23-77): Seventy-seven patients had modified radical mastectomies, 5 radical mastectomies and 1 simple mastectomy. Three patients ($4\%$) had pathologically negative axillae, and the remaining 80 ($96\%$) had positive axillae. Eleven, 23, 44 and 5 patients had pathological stages IIA, IIB, IIIA, and IIIB, retrospectively. Eighty ($96\%$) patients were treated with hockey-stick fields. The median dose of PMRT was 50.4 ey, in 1.8 Gy fractions. Adjuvant systemic chemotherapy was given to 74 patients ($89\%$). CMF-based or doxorubicin-containing regimens were given to 54 patients ($55\%$). The median follow-up time was 82 months (range, 8-171) after the mastectomy. Results: The 5 and 10-year overall survival rates for all patients were 65 and $49\%$, respectively. The univariate and multivariate analyses of the factors affecting the overall survival revealed the stage to be the most significant prognostic factor (p=0.002), followed by the combination of chemotherapy. Thirteen patients $16\%$ developed a LRF, at an interval of 4-84 months after radiotherapy, with a median of 20 months. The only significant prognostic factor affecting LRF was the combination of chemotherapy, in both the univariate and multivariate analyses. With respect to the sequence of chemoradiation, the sequence had no saatistical significance (p=0.90). According to the time interval from mastectomy to the onset of radiotherapy, the LRFR of the patients group treated by RT within or after 6 month postmastectomy 6 months were 14 vs. $27\%$ respectively (p=0.24). One third of the pa41en1s (26/83) developed distant metastasis, in 2-92 months, after radiotherapy, with a median of 21 months. The most commonly involved site was bone in 13 cases. The pathological staging was the only significant prognostic factor in both the univariate and multivariate analyses that affected distant failure. Radiological finding of radiation pneumonitis on a simple chest x-ray was shown in $20\%$ (17/83), with a time interval ranging from 2 to 7 months post-radiotherapy, with a median of 3 months. The stable lung fibrosis settled in 11 patients ($65\%$). Conclusion: It was concluded through this analysis that the combination of PMRT with in chemotherapy resulted in better overall survival and local control than PMRT alone in patients needing PMRT.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.345-352
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• 2001

Purpose : To evaluate the treatment results and prognostic factors after radiotherapy in stage IIB uterine cervix cancer. Materials and methods : We retrospectively analyzed the records of 90 patients with stage IIB uterine cervix cancer who received radiotherapy between 9/94 and 12/99. Age was ranged from 28 to 79 years (median 57). Tumor size was $\geq4\;cm$ in 64 patients. Preteatment SCC level was measured in 75 patients. Twenty nine patients received conventional radiotherapy (QD) and the others received modified hyper-fractionated radiotherapy (BID). Only 7 patients in BID had tumor size <4 cm. All patients received high dose rate brachytherapy $(4\;Gy\times7\;or\;5\;Gy\times6)$. No Patient received concurrent chemotherapy during radiotherapy. Follow up period was ranging from 9 to 76 months (median 38). Results : The 5-year overall and disease free survival rates were $73.4\%\;and\;71.6\%$, respectively. Local recurrences occurred in $10\%$ of patients, and distant metastasis in $18.9\%$. There was a significant correlation between OS/DFS and tumor size $(<4cm;\;OS\;95.2\%,\;DFS\;91.4\%,\;\geq4cm;\;OS\;63.4\%,\;DFS\;63.4\%)$. Pretreatment SCC level was one of prognostic factors only in univariate analysis. Conclusion : With modified hyperfractionated radiotherapy, there was very low local recurrence rate $(6.6\%)$ and high 5-year overall and disease free survival rate $(75.4\%\;and\;70.5\%)$, which is comparable to results after concurrent chemoradiotherapy in bulky, locally advanced stage IIB uterine cervix cancer.