• Korean Journal of Radiology
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• v.25 no.9
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• pp.788-797
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• 2024

Objective: To investigate the potential association among preoperative breast MRI features, axillary nodal burden (ANB), and disease-free survival (DFS) in patients with early-stage breast cancer. Materials and Methods: We retrospectively reviewed 297 patients with early-stage breast cancer (cT1-2N0M0) who underwent preoperative MRI between December 2016 and December 2018. Based on the number of positive axillary lymph nodes (LNs) determined by postoperative pathology, the patients were divided into high nodal burden (HNB; ≥3 positive LNs) and non-HNB (<3 positive LNs) groups. Univariable and multivariable logistic regression analyses were performed to identify independent risk factors associated with ANB. Predictive efficacy was evaluated using the receiver operating characteristic (ROC) curve and area under the curve (AUC). Univariable and multivariable Cox proportional hazards regression analyses were performed to determine preoperative features associated with DFS. Results: We included 47 and 250 patients in the HNB and non-HNB groups, respectively. Multivariable logistic regression analysis revealed that multifocality/multicentricity (adjusted odds ratio [OR] = 3.905, 95% confidence interval [CI]: 1.685-9.051, P = 0.001) and peritumoral edema (adjusted OR = 3.734, 95% CI: 1.644-8.479, P = 0.002) were independent risk factors for HNB. Combined peritumoral edema and ultifocality/multicentricity achieved an AUC of 0.760 (95% CI: 0.707-0.807) for predicting HNB, with a sensitivity and specificity of 83.0% and 63.2%, respectively. During the median follow-up period of 45 months (range, 5-61 months), 26 cases (8.75%) of breast cancer recurrence were observed. Multivariable Cox proportional hazards regression analysis indicated that younger age (adjusted hazard ratio [HR] = 3.166, 95% CI: 1.200-8.352, P = 0.021), larger tumor size (adjusted HR = 4.370, 95% CI: 1.671-11.428, P = 0.002), and multifocality/multicentricity (adjusted HR = 5.059, 95% CI: 2.166-11.818, P < 0.001) were independently associated with DFS. Conclusion: Preoperative breast MRI features may be associated with ANB and DFS in patients with early-stage breast cancer.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.67-71
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• 2024

A smart window based on a retarder can transmit or block polarized lights by overlapping two smart windows. In the study, tests were conducted to evaluate the performance of blocking solar heat using smart windows with a size of 300×300 mm². Solar heat gain coefficient (SHGC) values were derived through simulation using transmission and reflectance data of the smart windows. As a result of the simulation, it showed that SGHC is effective in blocking solar heat by obtaining values of 0.722 and 0.615 in transmission and blocking mode of smart windows, respectively. The test boxes were fabricated in order to verify the effect of suppressing temperature rise when applying smart windows, the inside temperature in test boxes, which are installed bare glass (reference) and two smart windows with transmission and blocking mode, were measured at 10 minutes-interval for 7 days. As of 1 p.m., the inside temperature of the test boxes with the smart windows applied showed lower temperature compared to the reference. In particular, on the day when the temperature of reference box was the highest at 66.1℃, the temperature of the test box with the smart window applied showed 61.0℃, which was lowered by 5.1℃.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.250-262
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• 2008

In order to assess the feasibility of the dipole-dipole electric method to the investigation of metallic ore deposit, both field data simulation and inversion are carried out for several simplified ore deposit models. Our interest is in a vein-type model, because most of the ore deposits (more than 70%) exist in a vein type in Korea. Based on the fact that the width of the vein-type ore deposits ranges from tens of centimeters to 2m, we change the width and the material property of the vein, and we use 40m-electrode spacing for our test. For the vein-type model with too small width, the low resistivity zone is not detected, even though the resistivity of the vein amounts to 1/300 of that of the surrounding rock. Considering a wide electrode interval and cell size used in the inversion, it is natural that the size of the low resistivity zone is overestimated. We also perform field data simulation and inversion for a vein-type model with surrounding hydrothermal alteration zones, which is a typical structure in an epithermal ore deposits. In the model, the material properties are assumed on the basis of resistivity values directly observed in a mine originated from an epithermal ore deposits. From this simulation, we can also note that the high resistivity value of the vein does not affect the results when the width of the vein is narrow. This indicates that our main target should be surrounding hydrothermal alteration zones rather than veins in field survey. From these results, we can summarize that when the vein is placed at the deep part and the difference of resistivity values between the vein and the surrounding rock is not large enough, we cannot detect low resistivity zone and interpret the subsurface structures incorrectly using the electric method performed at the surface. Although this work is a little simple, it can be used as references for field survey design and field data Interpretation. If we perform field data simulation and inversion for a number of models and provide some references, they will be helpful in real field survey and interpretation.

• Journal of Chest Surgery
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• v.30 no.5
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• pp.479-485
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• 1997

We investigated changes of the size of neoaortic annulus, root, and aortic anastomosis after arterial switch operation for complete transposition of the great arteries performed in infancy. A total of 23 patients were included in this study. Age ranged from 6 to 153 days. Body weight averaged 3.9$\pm$0.8kg and 17 patients were male. The preoperative angiocardiographic dimensions of the pulmonary annulus, the pulmonary root, and the sinotubular junction, standardized to the diameter of descending aorta at the level of diaphragm, were compared to the size of postoperative measurements of the neoaortic annulus, the neoaortic root, and the aortic an stomosis at a mean interval of 17.2$\pm$ 9.4 months. Mean dimensions of the neoaortic annulus and the neoaortic root were significantly increased postoperatively(n=23, annulus; p<0.01, root; p<0.01), however, those of the aortic anastomosis did not reveal significant change(n=23, p=0.06). There were no significant differences in changes of diameters of the neoaortic annulus, the root, and the aortic anastomosis between patients with(n=8) and without(n=15) postoperative neoaortic regurgitation(annulus; p=0.32, root; p=0.29, anastomosis; p=0.86). Postoperative dimensions of the neoaortic root and annulus between patients with ventricular septal defect(n: 10) and without ventricular septal defect(ni 13) were not significantly changed compared to the preoperative measurements(annulus; p=0.09, root; p=0.07) but mean diameters of the aortic anastomosis decreased significantly after operation in patients with ventricular septal defect(p=0.04). This study revealed that the site of the aortic an stomosis grows in proportion to patient's somatic growth after arterial switch operation. Although we could not demonstrate the relation between the aortic root dilatation and the postoperative neoaortic regurgitation in this study, a continuous close follow-up might be necessary to detect a possible progression of the aortic root dilatation and the resulting significant aortic valve regurgitation.

• Clinics in Shoulder and Elbow
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• v.13 no.1
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• pp.20-26
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• 2010

Purpose: To evaluate clinical features and surgical results for rotator cuff tear secondary to shoulder dislocation in middle-aged and elderly patients. Materials and Methods: We reviewed 19 patients over 50 years of age who had rotator cuff tears combined with shoulder dislocation between October 2004 and October 2008. There were 7 males and 12 females with a mean age 64.7 years (range, 50 to 78 years). The average follow-up duration was 22 months (range, 8 to 56 months). We investigated the number of dislocations, the size of the cuff tear, the presence of Bankart lesions and the time interval from dislocation to surgery. We also investigated the ASES score, UCLA score, SST score, and shoulder range of motion before and after surgery. We analyzed clinical outcomes and contributing factors. Results: ASES scores improved from 30.2 preoperatively to 72.3 postoperatively; UCLA scores improved from 12.9 to 26.5; SST scores improved from 2.4 to 7.3. Range of motion improved significantly: forward flexion, abduction, external rotation and internal rotation were, respectively, $110.8({\pm}39.3)^{\circ}$, $107.7({\pm}40)^{\circ}$, $22.5({\pm}17.6)^{\circ}$ and L5 level preoperatively; postoperatively they were $153.6({\pm}20.6)^{\circ}$, $152.1({\pm}20.8)^{\circ}$, $36.4({\pm}22.7)^{\circ}$ and L1 level. Age, the presence of Bankart lesions and the number of dislocations were not correlated with clinical outcomes. But the size of the cuff tear was correlated with clinical results. Also, the duration from dislocation to surgery was correlated with postoperative UCLA and SST scores (p=0.039, p=0.038). Conclusion: For shoulder dislocation, it is important to achieve early diagnoses of rotator cuff tears in middle-aged and elderly patients. If these injuries are both present, early rotator cuff repair should be performed for better clinical results.

• Radiation Oncology Journal
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• v.14 no.2
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• pp.149-158
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• 1996

Purpose : To get an accute steepness of dose gradients at outside the target volume in intracranial lesion and a less limitation of beam selection avoiding the high dose at normal brain tissue, this Photon Knife Radiosurgery System was developed in order to provide the three-dimensional dose distribution through the reconstruction of CT scan and the combined stereotactic trans-multiarc beam mode based on linear accelerator photon beam. Materials and methods : This stereotactic radiosurgery, Photon Knife based on linear accelerator photon beam was provided the non-coplanar multiarc and trans-multiarc irradiations. The stereotactic trans-multiarc beam mode can be obtained from the patient position in decubitus. This study has provided the 3-dimensional isodose curve and anatomical structures with the surface rendering technique. The dose distribution from the combined two trans-multiarcs (2M 2TM) was compared to that of four non-coplanar multiarcs (4M) with same collimator size of 25 mm in a diameter and total gantry movements. Results : In this study, it shows that the dose distributions of stereotactic beam mode are significantly depended on the selected couch and gantry angle in same collimator size. Practical dose distribution of combined stereotactic trans-multiarc beam has shown a more small rim thickness than that of the non-coplanar multiarc beam mode in axial, sagittal and coronal plane in our study. 3-Dimensional dose line displayed with surface rendering of irregular target shape is helpful to determine the target dose and to predict the prognosis in follow-up radiosurgery. Conclusions : 3-Dimensional dose line displayed with surface rendering of irregular target shape is essential in stereotactic radiosurgery. This combined stereotactic trans-multiarc beam has shown a less limitation of the selection couch and gantry beam angles for the target surrounding critical organs. It has shown that the dose distribution of combined trans-multiarc beam greatly depended on the couch and gantry angles. In our experiments, the absorbed dose has been decreased to $27%$ / mm in maximum at the interval of $50\%$ to $80\%$ of isodose line.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.3785-3791
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• 2016

Background: Previous studies have assessed the association between the Cytotoxic T-lymphocyte Antigen-4(CTLA-4) polymorphism with the risk of malignant bone tumor, but the conclusions were inconsistent. We aimed to clarify association of cytotoxic T-lymphocyte antigen-4 polymorphisms with malignant bone tumors risk by performing a meta-analysis. Materials and Methods: The databases including PubMed, EMBase databases and the Cochrane Library were searched to identify the eligible studies prior to January 30 2016. Odds ratio (OR) with 95% confidence interval (95%CI) were used to estimate the strengths of the association between the CTLA-4 polymorphism and the malignant bone tumor risks. The meta-analysis was performed by STATA 12.0. Results: Four individual studies with a total of 1003 cases with malignant bone tumor and 1162 controls were included in our meta-analysis. The results of meta-analysis on those data demonstrated that CTLA-4 +49G>A polymorphism was associated with the risk of Ewing's sarcoma and osteosarcoma strongly (A vs. G: OR=1.36, 95%CI:1.20-1.54, p=0.000; AA+AG vs. GG: OR=1.35, 95%CI:1.14-1.61, p=0.001; AA vs. GG: OR=2.24, 95%CI:1.67-2.99, p=0.000; AA vs. AG+GG: OR=2.00, 95%CI:1.53-2.62, p=0.000), but CTLA-4 -318C/T polymorphism was not associated with the risk of malignant bone tumor (C vs. T: OR=0.76, 95%CI:0.76-1.08, p= 0.262; CC+CT vs. TT: OR=0.70, 95%CI:0.41-1.20, p= 0.198; CC vs. TT: OR=0.69, 95%CI:0.40-1.19, p= 0.183; CC vs. CT+TT: OR=0.92, 95%CI:0.75-1.13, p= 0.419). Subgroup analysis showed that there are significantly positive correlations between CTLA-4 +49G>A polymorphism and increased risks of malignant bone tumors in large size of sample (A vs. G: OR=1.347, 95%CI: 1.172,1.548, p=0.000; AA vs. GG: OR=2.228, 95%CI: 1.608,3.085, p=0.000), Ewing's Sarcoma or Osteosarcoma (A vs. G: OR=1.361, 95%CI: 1.201,1.540, p=0.000; AA vs. GG: OR=2.236, 95%CI: 1.674,2.986, p=0.000), and PCR-RFLP or Sequencing(A vs. G: OR=1.361, 95%CI: 1.201,1.540, p=0.000; AA vs. GG: OR=2.236, 95%CI: 1.674,2.986, p=0.000), but CTLA-4 -318C/T polymorphism was not associated with the risk of malignant bone tumors in diagnosis, genotype method, and sample size (all p>0.05). Conclusions: CTLA-4 +49A/G variant was associated with an increased risk of developing the malignant bone tumors, such as Ewing's sarcoma and osteosarcoma. However, it failed to show the association between CTLA-4 -318C/T polymorphism and the risk of malignant bone tumors. Future large-scale studies remain to be done to confirm our conclusions.

• Management & Information Systems Review
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• v.23
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• pp.41-74
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• 2007

In Korea, corporate merger activities were activated since 1980, and nowadays(particuarly since 1986) the changes in domestic and international economic circumstances have made corporate managers have strong interests in merger. Korea and America have different business environments and it is easily conceivable that there exists many differences in motives, methods, and effects of mergers between the two countries. According to recent studies on takeover bids in America, takeover bids have information effects, tax implications, and co-insurance effects, and the form of payment(cash versus securities), the relative size of target and bidder, the leverage effect, Tobin's q, number of bidders(single versus multiple bidder), the time period (before 1968, 1968-1980, 1981 and later), and the target firm reaction (hostile versus friendly) are important determinants of the magnitude of takeover gains and their distribution between targets and bidders at the announcement of takeover bids. This study examines the theory of takeover bids, the status quo and problems of merger in Korea, and then investigates how the announcement of merger are reflected in common stock returns of bidding firms, finally explores empirically the factors influencing abnormal returns of bidding firms' stock price. The hypotheses of this study are as follows ; Shareholders of bidding firms benefit from mergers. And common stock returns of bidding firms at the announcement of takeover bids, shows significant differences according to the condition of the ratio of target size relative to bidding firm, whether the target being a member of the conglomerate to which bidding firm belongs, whether the target being a listed company, the time period(before 1986, 1986, and later), the number of bidding firm's stock in exchange for a stock of the target, whether the merger being a horizontal and vertical merger or a conglomerate merger, and the ratios of debt to equity capital of target and bidding firm. The data analyzed in this study were drawn from public announcements of proposals to acquire a target firm by means of merger. The sample contains all bidding firms which were listed in the stock market and also engaged in successful mergers in the period 1980 through 1992 for which there are daily stock returns. A merger bid was considered successful if it resulted in a completed merger and the target firm disappeared as a separate entity. The final sample contains 113 acquiring firms. The research hypotheses examined in this study are tested by applying an event-type methodology similar to that described in Dodd and Warner. The ordinary-least-squares coefficients of the market-model regression were estimated over the period t=-135 to t=-16 relative to the date of the proposal's initial announcement, t=0. Daily abnormal common stock returns were calculated for each firm i over the interval t=-15 to t=+15. A daily average abnormal return(AR) for each day t was computed. Average cumulative abnormal returns($CART_{T_1,T_2}$) were also derived by summing the $AR_t's$ over various intervals. The expected values of $AR_t$ and $CART_{T_1,T_2}$ are zero in the absence of abnormal performance. The test statistics of $AR_t$ and $CAR_{T_1,T_2}$ are based on the average standardized abnormal return($ASAR_t$) and the average standardized cumulative abnormal return ($ASCAR_{T_1,T_2}$), respectively. Assuming that the individual abnormal returns are normal and independent across t and across securities, the statistics $Z_t$ and $Z_{T_1,T_2}$ which follow a unit-normal distribution(Dodd and Warner), are used to test the hypotheses that the average standardized abnormal returns and the average cumulative standardized abnormal returns equal zero.

• Clinics in Shoulder and Elbow
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• v.15 no.1
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• pp.8-15
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• 2012

Purpose: The object of this study was to investigate the difference in torque and pullout strength between the standard anchor insertion (5.0 mm) with a small awl (3.7 mm) and larger anchor insertion (6.5 mm), with a standard awl (5.0 mm) in osteoporotic humeral head. Materials and Methods: The embalmed 24 paired cadaveric shoulders were assigned to either Group A or B. After measuring the bone mineral density (BMD) of the ROI (region of interest) in the humeral head, 5.0 mm suture anchors were inserted using a 3.7 mm awl in Group A1, and the same 5.0 mm anchors were inserted using a 5.0 mm awl in Group A2. The 5.0 mm anchors were inserted using a 5.0 mm awl in Group B1, and 6.5 mm anchors were inserted using a 5.0 mm awl in Group B2. We measured the torques at the time of the anchor insertion and pullout strengths. Results: There was no significant difference in the BMD between the groups. The torque of A1 (20.6 $cN{\cdot}m$) was significantly higher than that of A2 (13.2 $cN{\cdot}m$), and the torque of B2 (20.8 $cN{\cdot}m$) was significantly higher than that of B1(12.1 $cN{\cdot}m$). However, the difference in the increased torque between group A and B was not significant. The pullout strength of A1 (204.2 N) was significantly higher than that of A2 (152.9 N), and the pullout strength of B2 (210.9 N) was significantly higher than that of B1 (149.5 N). However, the difference in the increased pullout strength between Group A and B was not significant. Conclusion: In severe osteoporosis, the use of a larger suture anchor with a standard awl increased the torque and pullout strength significantly, in comparison to the use of the same sized suture anchor and awl. If there is an inadequate interval between the anchors on the greater tuberosity, the use of a 3.7 mm awl and 5.0 mm anchor will be beneficial compared to that of a 5.0 mm awl and 6.5 mm anchor, considering that an increase in the pullout strength does not depend on the awl size.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.135-144
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• 2010

Purpose: The purpose of this study is that through production of phantom for respiration gated radiotherapy, assessing appropriacy of exposure dose for the therapy using RPM (Real-time Position Management). Materials and Methods: We located measurement object on the phantom for respiration gated radiotherapy made of 2 linear actuator, acrylic panel, stanchion, iron plate ets. to drive (up, down, front, back). Using 4D CT scan, we analyzed patient's respiration and reproduced the movement by computer. On the phantom, we located a 2D-Array (PTW) and an White water phantom (4.5 cm) and used DMLC (interval 2 cm) in the field size $10{\times}10\;cm$, then exposed 21EX X-ray 100 MU, in the case of phantom was (1) static (2) moving (3) gated using RPM respectively gantry $0^{\circ}$ and $90^{\circ}$ We measured with a 0.125 CC ionization chamber (PTW) on the phantom (7.5 cm) in the same condition. Results: Ionization chamber: There were within 0.3% of error with gating respiration and approximately 2% of error without gating in the same condition. 2D-Array: Gantry $90^{\circ}$, field size $10{\times}10\;cm$, using DMLC. There were within 3% of error with gating respiration and approximately 16% of error without gating. Conclusion: The phantom for respiration gated radiotherapy makes plans considering patient's movement, quantitative analysis of exposure dose and proper assessment therapy for IMRT patients using RPM possible.