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Active and Passive Suppression of Composite Panel Flutter Using Piezoceramics with Shunt Circuits (션트회로에 연결된 압전세라믹을 이용한 복합재료 패널 플리터의 능동 및 수동 제어)

  • 문성환;김승조
    • Composites Research
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    • v.13 no.5
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    • pp.50-59
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    • 2000
  • In this paper, two methods to suppress flutter of the composite panel are examined. First, in the active control method, a controller based on the linear optimal control theory is designed and control input voltage is applied on the actuators and a PZT is used as actuator. Second, a new technique, passive suppression scheme, is suggested for suppression of the nonlinear panel flutter. In the passive suppression scheme, a shunt circuit which consists of inductor-resistor is used to increase damping of the system and as a result the flutter can be attenuated. A passive damping technology, which is believed to be more robust suppression system in practical operation, requires very little or no electrical power and additional apparatuses such as sensor system and controller are not needed. To achieve the great actuating force/damping effect, the optimal shape and location of the actuators are determined by using genetic algorithms. The governing equations are derived by using extended Hamilton's principle. They are based on the nonlinear von Karman strain-displacement relationship for the panel structure and quasi-steady first-order piston theory for the supersonic airflow. The discretized finite element equations are obtained by using 4-node conforming plate element. A modal reduction is performed to the finite element equations in order to suppress the panel flutter effectively and nonlinear-coupled modal equations are obtained. Numerical suppression results, which are based on the reduced nonlinear modal equations, are presented in time domain by using Newmark nonlinear time integration method.

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Clinical Analysis of Surgically Treated Thyroid Nodules (외과적 치료를 시행한 갑상선 결절의 임상적 고찰)

  • Chang Yong-Keun;Kim Kweon-Cheon
    • Korean Journal of Head & Neck Oncology
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    • v.15 no.1
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    • pp.70-75
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    • 1999
  • Objectives: This study was designed to evaluate the methods of diagnosis and treatment of thyroid nodules. Materials and Methods : We performed a clinical review of patients with thyroid nodules, who were surgically treated at the Department of Surgery, College of Medicine, Chosun University from January 1996 to December 1998. Results: 1) The patients were divided into two groups; 65 patients(80.2%) with benign nodular disease and 16 patients(19.8%) with malignant disease. 2) The sex distribution showed a preponderance of females with a ratio of 5.2:1 in benign nodular disease and 3:1 in malignant disease. Benign nodules were more prevalent in patients in their 40's as compared to malignant nodules in patients in their 50's and 60's. 3) The most common duration of illness was 3 months, occurring in 45.7% of the total cases. 4) The most prominent symptom and sign was a palpable nodule in the anterior aspect of the neck. 5) The location of the nodule was ; 41 cases in the right lobe, 29 cases in the left lobe, and 11 cases in both lobes. 6) Thyroid scanning of 40 patients revealed cold nodules in 90.6% of benign nodules and in all malignant disease. 7) Fine needle aspiration cytology were performed in 32 cases of the 81 patients. Comparing with postoperative pathological findings, the results were the same in 87.5% of 32 cases. 8) Intra-operative frozen section study was performed in 56 cases of the 81 patients. Comparing with postoperative pathological finding, the results were same in 96.4% of the 56 cases. 9) The histopathological classification revealed that adenomatous goiters were the most common benign disease and papillary carcinomas were the most common malignant disease. 10) The most frequently employed operation for benign nodules and malignant disease was unilateral total lobectomy. When the metastasis was confirmed, lymphadenectomy and radical neck dissection was performed in malignant disease. 11) Important postoperative complications were transient hoarseness, transient hypocalcemia, hypothyroidism, wound bleeding, and hoarseness. Conclusions: The results of this study suggest that palpable nodules in anterior aspect of neck is revealed cold nodule by thyroid scanning and malignancy by fine needle aspiration cytology, which should be removed surgically. There is no difference in complication and survival rate with type of operation and lymphatic dissection. Therefore, procedure of operation is dependent on the site of nodule and involvement of lymph node.

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Treatment of MFH(Malignant fibrous histiocytoma) in Extremity (사지에 발생한 악성섬유조직구종의 치료 경험)

  • Kang, Jong Hwa;Lee, Won Jai;Lew, Dae Hyun;Rah, Dong Kyun;Tark, Kwan Chul
    • Archives of Plastic Surgery
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    • v.35 no.4
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    • pp.439-445
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    • 2008
  • Purpose: Malignant fibrous histiocytoma(MFH) is the most common soft tissue sarcoma in adult. As to this date, tissue development, treatment and prognosis of the tumor has not been definitely clarified, however, it has been reported that wide surgical resection of the tumor along with the radiotheraphy and chemotheraphy is needed for treatment. In MFH with high recurrence rate, the reconstruction method and points to be considered for reconstruction in recurrent case were studied in 10 patients who were treated in our hospital. Methods: From August of 1991 to August 2007, location of tumor, initial mass size, 1st recurred period, lymph node metastasis, recurrence rate, treatment modality, complication, reconstruction in recurrent defect, and follow up period was studied in 10 patients who underwent reconstruction at our Plastic surgery department following wide excision. Results: The average age was 62.8(46 - 73) years old, average follow up period was 7.7(1 - 17) years. Various reconstructions has been performed for recurrent cases and postoperative chemotheraphy and radiotheraphy was done. As for reconstruction in recurrent cases, After wide excision, local flap was performed in 6 cases, and free flap in 2 cases. After radiotherapy, osteoradionecrosis was occurred in 4 cases. Recurrence rate was 1 - 5(2.6) times and reconstruction due to recurrence was 7 out of 10 cases(70%). Conclusion: The treatment modality of MFH is not yet defined. Due to it's high recurrence rate, radiotherapy and chemotherapy is commonly combined with surgery. Even still, additional excision and reconstruction may be required. Therefore, possibility of re-operation must be considered when performing every excision and reconstruction; in case a recurrence or osteoradionecrosis occurs. Free flap coverage should be left as the last resort, according to the principle of reconstruction. Nevertheless, if the defect is large or osteoradionecrosis is present, it will benefit greatly to the patient's quality of life.

High School Students' Understanding of Astronomical Concepts Using the Role-playing and Discussion in Small Groups (소집단 역할놀이와 토의를 통한 고등학생들의 천문개념 이해)

  • Jung, Nam-Sik;Woo, Jong-Ok;Jeong, Jin-Woo
    • Journal of The Korean Association For Science Education
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    • v.16 no.1
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    • pp.61-76
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    • 1996
  • The purpose of this study was to apply the instructional strategies for conceptual change prescribed by Posner et al(1982) to the astronomic content domain taught in the elementary and middle school and to analyze the characteristics of students' knowledge revealed in the test before, during and after the instruction. Also, it was to investigate the intercorrelation of cognitive levels, spatial ability and science achievement. The major findings of this study are as follows: 1. Students had a great variety of misconceptions related to the motion of the moon before the instruction, that is, the phases, the names of phases and the cause of changing phases by the moon's orbit about the earth, the moon's appearance and location at the given time, the relative positions of earth, moon and sun during a lunar eclipse, the cause that a full moon is not at the line of node once a month. In the analysis of students' responses concerning the cause of changing phases of the moon and a lunar eclipse, the results indicate that the great majority of students had rote learning rather than meaningful learning in the middle school. 2. Students' reponses during the instruction concerning the changing phases of the moon and the predictive knowledge about the motions of the earth and the moon were analyzed. 1) According to the results of the test given before and after experiment, after discussion, achievement score of the whole of subjects and groups in both preformal and formal cognitive levels appeared to increase linearly. 2) There was no statistically significant differences of achievement scores before and after experiment, after discussion between preformal group and formal group in cognitive levels. 3. Distribution of achievement scores according to the whole of subjects and groups in preformal and formal cognitive levels shows that there was a statistically significant difference between pretest and posttest. 4. Types of conceptual changes concerning the cause of changing phases of the moon that occurred from pretest to posttest were classified as accommodation, incomplete accommodation, assimilation, no change and no model. Six of the seven students starting instruction with alternative frameworks didn't sustain those alternative models throughout instruction. Five of these six students accommodated completely and the last one partially. Seventy-nine percentage of students taking instruction with fragmental models assimilated correct propositions at the end of the instruction. These results suggest that conceptual change model prescribed by Posner et al(1982) has promised the meaningful learning to students taking with fragmental models, especially in cases where students with misconception enter instruction. 5. High correlation between achievement score of simple-recall items and that of written items in pretest and posttest indicates that the higher students got the score in simple-recall items the better they also performed in written items. However, there was no statistically significant differences among cognitive levels, spatial ability and science achievement in the whole of subjects and groups according to the cognitive levels.

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A Clustering Technique to Minimize Energy Consumption of Sensor networks by using Enhanced Genetic Algorithm (진보된 유전자 알고리즘 이용하여 센서 네트워크의 에너지 소모를 최소화하는 클러스터링 기법)

  • Seo, Hyun-Sik;Oh, Se-Jin;Lee, Chae-Woo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.2
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    • pp.27-37
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    • 2009
  • Sensor nodes forming a sensor network have limited energy capacity such as small batteries and when these nodes are placed in a specific field, it is important to research minimizing sensor nodes' energy consumption because of difficulty in supplying additional energy for the sensor nodes. Clustering has been in the limelight as one of efficient techniques to reduce sensor nodes' energy consumption in sensor networks. However, energy saving results can vary greatly depending on election of cluster heads, the number and size of clusters and the distance among the sensor nodes. /This research has an aim to find the optimal set of clusters which can reduce sensor nodes' energy consumption. We use a Genetic Algorithm(GA), a stochastic search technique used in computing, to find optimal solutions. GA performs searching through evolution processes to find optimal clusters in terms of energy efficiency. Our results show that GA is more efficient than LEACH which is a clustering algorithm without evolution processes. The two-dimensional GA (2D-GA) proposed in this research can perform more efficient gene evolution than one-dimensional GA(1D-GA)by giving unique location information to each node existing in chromosomes. As a result, the 2D-GA can find rapidly and effectively optimal clusters to maximize lifetime of the sensor networks.

Estimation of the Regional Future Sea Level Rise Using Long-term Tidal Data in the Korean Peninsula (장기 조위자료를 이용한 한반도 권역별 미래 해수면 상승 추정)

  • Lee, Cheol-Eung;Kim, Sang Ug;Lee, Yeong Seob
    • Journal of Korea Water Resources Association
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    • v.47 no.9
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    • pp.753-766
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    • 2014
  • The future mean sea level rise (MSLR) due to climate change in major harbors of Korean Peninsula has been estimated by some statistical methods in this article. Firstly, Mann-Kendall non-parametric trend test to find some trend in the observed long-term tidal data has been performed and also Bayesian change point analysis has been used also to detect the location of change points and their magnitude quantitatively. Especially, in this study, the results from Bayesian change point analysis have been applied to combine 4 future MSLR scenario projections with local MSLR data at 5 tidal gauges. This proposed procedure including Bayesian change point analysis results can improve the step for the determination of starting years of future MLSR scenario projections with 18.6-year lunar node tidal cycle and effectively consider local characteristics at each gauge. The final results by the proposed procedure in this study have shown that the future MSLR in Jeju region (Jeju tidal gauge) is in the largest increment and also the future MSLRs in Western region (Boryeong tidal gauge) and Southern region (Busan tidal gauge) are in the second largest one. Finally, it has been shown that the future MSLRs in Southern region (Yeosu tidal gauge) and Eastern region (Sokcho tidal gauge) seem to be in the relatively smallest growth among 5 gauges.

Reabsorption of Neutral Amino Acids Mediated by Amino Acid Transporter LAT2 and TAT1 in The Basolateral Membrane of Proximal Tubule

  • Park Sun Young;Kim Jong-Keun;Kim In Jin;Choi Bong Kyu;Jung Kyu Yong;Lee Seoul;Park Kyung Jin;Chairoungdua Arthit;Kanai Yoshikatsu;Endou Hitoshi;Kim Do Kyung
    • Archives of Pharmacal Research
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    • v.28 no.4
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    • pp.421-432
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    • 2005
  • In order to understand the renal reabsorption mechanism of neutral amino acids via amino acid transporters, we have isolated human L-type amino acid transporter 2 (hLAT2) and human T-type amino acid transporter 1 (hTAT1) in human, then, we have examined and compared the gene structures, the functional characterizations and the localization in human kidney. Northern blot analysis showed that hLAT2 mRNA was expressed at high levels in the heart, brain, placenta, kidney, spleen, prostate, testis, ovary, lymph node and the fetal liver. The hTAT1 mRNA was detected at high levels in the heart, placenta, liver, skeletal muscle, kidney, pancreas, spleen, thymus and prostate. Immunohistochemical analysis on the human kidney revealed that the hLAT2 and hTAT1 proteins coexist in the basolateral membrane of the renal proximal tubules. The hLAT2 transports all neutral amino acids and hTAT1 transports aromatic amino acids. The basolateral location of the hLAT2 and hTAT1 proteins in the renal proximal tubule as well as the amino acid transport activity of hLAT2 and hTAT1 suggests that these transporters contribute to the renal reabsorption of neutral and aromatic amino acids in the basolateral domain of epithelial proximal tubule cells, respectively. Therefore, LAT2 and TAT1 play essential roles in the reabsorption of neutral amino acids from the epithelial cells to the blood stream in the kidney. Because LAT2 and TAT1 are essential to the efficient absorption of neutral amino acids from the kidney, their defects might be involved in the pathogenesis of disorders caused by a disruption in amino acid absorption such as blue diaper syndrome.

The Results of the ATP Based Chemotherapy Response Assay in Gastric Cancer Tissues (ATP-CRA 방법을 이용한 위암조직의 항암제 감수성 검사결과)

  • Lee, Je-Hyung
    • Journal of Gastric Cancer
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    • v.7 no.3
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    • pp.160-166
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    • 2007
  • Purpose: Recently, chemosensitivity tests have become widely used for the selection of effective drugs in gastric cancer patients. In this study, a chemosensitivity test was performed to select agents to increase the effectiveness of adjuvant chemotherapy. Materials and Methods: Chemosensitivity testing was performed in 81 gastric cancer patients that received a gastrectomy at the Yeungnam University Hospital. An ATP (adenosine triphosphate) based chemotherapy response assay was used. Clinicopatholgical factors such as sex, age, expression of tumor markers (CEA and CA19-9 levels), location of the tumor, morphology of advanced cancer, histological type, cell differentiation, depth of invasion, Lauren classification, Ming classification, lymphatic invasion, vascular invasion, neural invasion, lymph node metastasis and TNM stage were used to correlate the chemosensitivity and clinicopathological factors. Results: The most effective antitumor agents in gastric cancer patients were (in order of effectiveness) 5-FU, Epirubicin, lrinotecan and Oxaliplatin in our series. The chemosensitivity test showed a significant difference in susceptibility according to clinicopathological factors. Conclusion: Further studies on multidrug therapy are needed to evaluate synergistic effects of drugs. Therefore, for effective chemotherapy, it is more efficacious to select a chemosensitive drug than continue to use the same drug regimen.

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Clinical Implications of Microsatellite Instability in Early Gastric Cancer

  • Kim, Dong Gyu;An, Ji Yeong;Kim, Hyunki;Shin, Su-Jin;Choi, Seohee;Seo, Won Jun;Roh, Chul Kyu;Cho, Minah;Son, Taeil;Kim, Hyoung-Il;Cheong, Jae-Ho;Hyung, Woo Jin;Noh, Sung Hoon;Choi, Yoon Young
    • Journal of Gastric Cancer
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    • v.19 no.4
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    • pp.427-437
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    • 2019
  • Purpose: We aimed to evaluate the clinical characteristics of microsatellite instability in early gastric cancer. Materials and Methods: The microsatellite instability status of resected early gastric tumors was evaluated using two mononucleotide repeat markers (BAT25 and BAT26) and three dinucleotide repeat markers (D5S346, D2S123, and D17S250). Tumors with instability in two or more markers were defined as microsatellite instability-high (MSI-H) and others were classified as microsatellite stable (MSS). Results: Overall, 1,156 tumors were included in the analysis, with 85 (7.4%) classified as MSI-H compared with MSS tumors. For MSI-H tumors, there was a significant correlation with the female sex, older age, tumor location in the lower gastric body, intestinal histology, lymphovascular invasion (LVI), and submucosal invasion (P<0.05). There was also a trend toward an association with lymph node (LN) metastasis (P=0.056). In mucosal gastric cancer, there was no significant difference in MSI status in tumors with LN metastasis or tumors with LVI. In submucosal gastric cancer, LVI was more frequently observed in MSI-H than in MSS tumors (38.9% vs. 25.0%, P=0.027), but there was no difference in the presence of LN metastases. The prognosis of MSI-H tumors was similar to that of MSS tumors (log-rank test, P=0.797, the hazard ratio for MSI-H was adjusted by age, sex, pT stage, and the number of metastatic LNs, 0.932; 95% confidence interval, 0.423-2.054; P=0.861). Conclusions: MSI status was not useful in predicting prognosis in early gastric cancer. However, the frequent presence of LVI in early MSI-H gastric cancer may help guide the appropriate treatment for patients, such as endoscopic treatment or limited LN surgical dissection.

A Clinicopathologic Analysis of Neck Masses (경부 종괴의 임상 및 병리학적 고찰)

  • Km Jeong-Ho;Oh Sang-Hoon;Kim Sang-Hyo
    • Korean Journal of Head & Neck Oncology
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    • v.13 no.1
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    • pp.51-57
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    • 1997
  • A mass appearing in the anterior or lateral side of neck often can be a diagnostic challenge. Differential diagnosis of the neck mass covers a broad spectrum of diseases and the proper evaluation and management of a neck mass requires an impressive amount of anatomic and pathologic information. Because improper diagnosis and management may convert a potentially curable malignant metastasis into incurable disease, a differential diagnosis must be considered in all patients who present with a neck mass. Authors reviewed 2,148 cases of neck mass who were diagnosed by surgical resection, biopsy or aspiration during the period between October 1982 to December 1993, excluding those with thyroid and parathyroid disease. The evaluated characteristics were age, sex, site of lesion, and pathologic diagnosis. The results were as follows: Of 2,148 cases of neck mass, the overall ratio of benign to malignant tumor was 3 : 1. In 1,603 cases of benign mass lesion, the most common disease was lymphadenitis(non-specific and tuberculosis) showing 53% incidence, the second was salivary gland tumor(13%), and the third was congenital lesion(12%). The minor problems such as lipoma and sebaceous cyst were 21 %. In the age distribution of benign lesion, tuberculous lymphadenitis showed peak incidence in second decade, non-specific lymphadenitis was main disease of childhood, salivary gland tumor was peak in fourth decade, and most of congenital lesions were diagnosed at the age below 15. In 545 malignant tumors, the most common lesion was metastatic cancer to cervical lymph nodes yielding 71 % incidence(head and neck primary 52%, infraclavicular primary 42%, unknown primary 5%), the second common disease was lymphoma(19%), and the third was salivary gland cancer(9%). In the age incidence of malignant tumor, 60% of them developed in the fifth and sixth decade, head and neck primary was more common in the fifth decade than sixth, however lymphoma showed higher incidence in sixth decade. In the analysis of mass location according to lymph node level grouping(I - V), lymphadenitis developed mostly in level V nodes, the next common occurring site was level IV in tuberculous lymphadenitis and level II in non-specific lymphadenitis. The majority of metastatic cancers were found in level IV and III, and common occurring site of lymphoma was in level II and IV. Pathologic diagnosis of neck masses were made by fine needle aspiration cytology 80 cases, incisional biopsy 533 cases, excisional surgery 1,399 cases, and neck dissection 116 cases. For the proper management of neck mass, a proper diagnostic modality should be selected from imaging techniques, cytology, biopsy or neck dissection, with the consideration of patient's age, history and clinical findings. The scapel biopsy could be used freely in the inflammatory disease or inoperable metastatic cancer, but it should be reserved in the curable metastatic cancer or clinically possible malignancy.

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