• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.28-37
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• 2022

The burning rate estimation method of solid propellants, based on closed bomb tests, has been introduced. The composition of the combustion gas is determined by using CEA and the Noble-Abel equation of state for high pressure operation conditions. Covolume taking into account the collision among molecules due to the actual volume of the molecule is modeled by LJ potential. A cubic form function is applied to calculate the volume change of propellant grains during combustion. The estimated burning rates of five different grain configuation at high pressure are fairly compared with BRLCB results within the maximum error of 6%.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.345-348
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• 2003

본 논문에서는 이 문서 클러스터링 방법 중 계층적 방법인 Kmeans 클러스터링 알고리즘을 이용하여 문서를 클러스터링 하고자 한다 기존의 Kmeans 클러스터링 알고리즘은 문서의 수가 많을 경우 하나의 클러스터링에 너무 많은 문서들이 할당되는 문제점이 있다. 이 치우침을 완화하고자 각 클러스터링에 할당된 문서 수에 따라서 문서에 가중치를 부여한 후 다시 클러스터링을 하는 방법을 제안하였다. 실험 결과는 정확률, 재현율을 결합한 조화 평균(F-measure)를 사용하여 평가하였으며 기존 알고리즘보다 9%이상의 성능 향상을 나타냈다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.246-251
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• 2013

In this paper, it is proposed a bandwidth allocation Scheme based on Bankruptcy theory in Distributed Mobile Multimedia Network. The proposed scheme is guaranteed a minimum allocation. So, the minimum quality of each service are guaranteed. Therefore efficient and fairness network can be configured. The performance evaluation results indicate that the proposed scheme has good performance than other existing schemes by the fairness index and the Erlang blocking formular calculation. The minimum bandwidth of the proposed scheme can be applied to other techniques of a priority based bandwidth allocation scheme and dynamic bandwidth allocation scheme.

• Radiation Oncology Journal
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• v.21 no.1
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• pp.44-65
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• 2003

Purpose : To conduct nationwide surgery on the principles In radiotherapy for rectal center, and develop the framework of a database of Korean Patterns of Care Study. Materials and Methods : A consensus committee was established to develop a tool for measuring the Patterns in radiotherapy Protocols for rectal cancer. The Panel was composed of radiation oncologists from 18 hospitals in Seoul Wetropolltan area. The committee developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer. The survey items developed for measuring the treatment principles were composed of 1) 8 eliglblllty criteria, 2) 20 Items for staging work-ups and prognostic factors, 3) 7 Items for principles of combined surgery and chemotherapy, 4) 9 patient set-ups, 5) 19 determining radiation fields, 6) S radiotherapy treatment pians, 7) 4 physicalilaboratory examination to monitor a patient's condition during treatment, and 8) 10 follow-up evaluations. These items were sent to radiation oncoioglsts In charge of gastrolntestlnal malignancies in all hospitals (48 hospitals) In Korea to which 30 replies were received (63$\%$). Results : Most of the surrey Items were replied to without no major between the repliers, but with the fellowing items only 50$\%$ of repliers were in agreement : 1) Indications of preoperative radiation, 2) use of endorectal ultrasound, CT scan, and bone scan for staging work-ups, 3) principles of combining chemotherapy with radiotherapy, 4) use of contrast material for small bowel delineation during simulation, 5) determination of field margins, and 6) use of CEA and colonoscopy for follow-up evaluations. Conclusions : The Items where considerable disaggrement was shown among the radiation oncologists seemed to make no serious difference In the treatment outcome, but a practical and reasonable consensus should be reached by the committee, with logical processes of agreement. These Items can be used for a basic database for the Patterns of Care Study, which will survey the practical radiotherapy Patterns for rectal cancer in Korea.

• Journal of Yeungnam Medical Science
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• v.16 no.1
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• pp.76-84
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• 1999

The differentiation between malignancy-related ascites(MRA) and non-malignant ascites (NMA) is important for further diagnostic and therapeutic purposes. Although many parameters were investigated, none has provided a complete distinction between MRA and NMA. We investigated several ascitic fluid parameters to determine the differential power, and to differentiate malignant-related from nonmalignant-related ascites with a sequence of sensitive parameters followed by specific parameters. For the present study, 80 patients with ascites were divided into two groups: MRA and NMA, The MRA group was consisted of 27 patients with proven malignancy by image study, biopsy, and follow up: 21 of these patients had peritoneal carcinomatosis, but the remaining 6 showed no evidence of peritoneal carcinomatosis. The NMA group was consisted of 53 patients with no evidence of malignancy: among these patients, one had SLE, and others had liver cirrhosis, The samples of blood and ascites were obtained simultaneously, and then the levels of ascites cholesterol, CEA. protein and LDH, cytology, albumin gradient, ascites/serum concen-tration ratios of LDH(LDH A/S), and ascites/serum concentration ratios of protein(protein A/S) were measured. Applying cut-off limits for determined parameters, we estimated the diagnostic efficacy of each parameter, Among the eight parameters investigated, ascites fluid cholesterol yielded the best sensitive value of 93%(cut-off value 30mg/dl), and cytologic examination and the protein A/S(cut-off value 0.5) showed the most specific value of 100% and 96%, respectively. Based on the above results, the diagnostic sequence with cholesterol as a sensitive parameter followed by the combination of cytologic examination and protein A/S as specific parameters, was tested in 80 patients. This diagnostic sequence identified 81.5% of patients with malignancy, and all patients with peritoneal carcinomatosis were classified as malignancy-related ascites. In spite of many limitations, this proposed diagnostic sequence may permit a cost-effective and simple differentiation of malignancy-related ascites from nonmalignant ascites.

• The Korean Journal of Nuclear Medicine Technology
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• v.25 no.1
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• pp.34-40
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• 2021

Purpose If a new test is introduced or reagents are changed in the laboratory of a medical institution, the characteristics of the test should be analyzed according to the procedure and the assessment of reagents should be made. However, several necessary conditions must be met to perform all required comparative evaluations, first enough samples should be prepared for each test, and secondly, various reagents applicable to the comparative evaluations must be supplied. Even if enough comparative evaluations have been done, there is a limit to the fact that the data variation for the new reagent represents the overall patient data variation, The fact puts a burden on the laboratory to the change the reagent. Due to these various difficulties, reagent changes in the laboratory are limited. In order to introduce a competitive bid, the institute conducted a full investigation of Radioimmunoassay(RIA) reagents for each test and established the range of reagents available in the laboratory through comparative evaluations. We wanted to share this process. Materials and Methods There are 20 items of tests conducted in our laboratory except for consignment tests. For each test, RIA reagents that can be used were fully investigated with the reference to external quality control report. and the manuals for each reagent were obtained. Each reagent was checked for the manual to check the test method, Incubation time, sample volume needed for the test. After that, the primary selection was made according to whether it was available in this laboratory. The primary selected reagents were supplied with 2kits based on 100tests, and the data correlation test, sensitivity measurement, recovery rate measurement, and dilution test were conducted. The secondary selection was performed according to the results of the comparative evaluation. The reagents that passed the primary and secondary selections were submitted to the competitive bidding list. In the case of reagent is designated as a singular, we submitted a explanatory statement with the data obtained during the primary and secondary selection processes. Results Excluded from the primary selection was the case where TAT was expected to be delayed at the moment, and it was impossible to apply to our equipment due to the large volume of reagents used during the test. In the primary selection, there were five items which only one reagent was available.(squamous cell carcinoma Ag(SCC Ag), β-human chorionic gonadotropin(β-HCG), vitamin B12, folate, free testosterone), two reagents were available(CA19-9, CA125, CA72-4, ferritin, thyroglobulin antibody(TG Ab), microsomal antibody(Mic Ab), thyroid stimulating hormone-receptor-antibody(TSH-R-Ab), calcitonin), three reagents were available (triiodothyronine(T3), Tree T3, Free T4, TSH, intact parathyroid hormone(intact PTH)) and four reagents were available are carcinoembryonic antigen(CEA), TG. In the secondary selection, there were eight items which only one reagent was available.(ferritin, TG, CA19-9, SCC, β-HCG, vitaminB12, folate, free testosterone), two reagents were available(TG Ab, Mic Ab, TSH-R-Ab, CA125, CA72-4, intact PTH, calcitonin), three reagents were available(T3, Tree T3, Free T4, TSH, CEA). Reasons excluded from the secondary selection were the lack of reagent supply for comparative evaluations, the problems with data reproducibility, and the inability to accept data variations. The most problematic part of comparative evaluations was sample collection. It didn't matter if the number of samples requested was large and the capacity needed for the test was small. It was difficult to collect various concentration samples in the case of a small number of tests(100 cases per month or less), and it was difficult to conduct a recovery rate test in the case of a relatively large volume of samples required for a single test(more than 100 uL). In addition, the lack of dilution solution or standard zero material for sensitivity measurement or dilution tests was one of the problems. Conclusion Comparative evaluation for changing test reagents require appropriate preparation time to collect diverse and sufficient samples. In addition, setting the total sample volume and reagent volume range required for comparative evaluations, depending on the sample volume and reagent volume required for one test, will reduce the burden of sample collection and planning for each comparative evaluation.

• The Korean Journal of Nuclear Medicine Technology
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• v.25 no.1
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• pp.41-43
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• 2021

Purpose In nuclear medicine blood tests, hemolysis samples are considered as inappropriate sample and are recommended not to be used for blood test. So, the lab are required to collect the blood again in the blood collection room However, The effect of hemolyzed samples on radioimmunoassay has not studied yet. This study was designed to evaluate effects of hemolysis on radioimmunoassay. Materials and Methods The kit manuals of 23 test items were reviewed to confirm whether hemolyzed samples were used. The subjects were 19 general applicants(male : 9, female : 13) and the samples were collected by each two SST tubes, one tube was obtained by centrifugation normally, and the other was obtained hemolyzed sample by centrifugation after external shock. It has been known that highly hemolyzed samples can affect the test results, so the test was performed using the severe hemolyzed sample. The test was performed for each test item using 23 normal serum and hemolysis serum, and SPSS19 program was used for statistical comparison of the test result. Results There was no significant difference between normal serum and hemolysis serum in 21 of 23 test items, but the results of insulin and C-peptide were significantly different(P<0.05). Conclusion It has been known that hemolysis in blood samples can affect the results of biochemical and hematological test, However, hemolysis effect is relatively low. Similarly, this study showed that hemolysis had not much effect on most of immunological radioimmunoassay except for some tests. Therefore, it is thought that the demand for re-collection due to hemolysis will be reduced in the laboratory, which will improve the work process of the laboratory.

• Radiation Oncology Journal
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• v.23 no.1
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• pp.22-31
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• 2005

Purpose : To conduct a nationwide survey on the principals in radiotherapy for rectal cancer, and produce a database of Korean Patterns of Care Study. Materials and Methods : We developed web-based Patterns of Care Study system and a national survey was conducted using random sampling based on power allocation methods. Eligible patients were who had postoperative radiotherapy for rectal cancer without gross residual tumor after surgical resection and without previous history of other cancer and radiotherapy to pelvis. Data of patients were Inputted to the web based PCS system by each investigators in 19 institutions. Results : Informations on 309 patients with rectal cancer who received radiotherapy between 1998 and 1999 were collected. Male to female ratio was 59 : 41, and the most common location of tumor was lower rectum ($46\%$). Preoperative CEA was checked in $79\%$ of cases and its value was higher than 6 ng/ml in $32\%$. Pathologic stage were I in $1.5\%$, II in $32\%$, III in $53\%$, and IV in $1.6\%$. Low anterior resection was the most common type of surgery and complete resection was peformed in $95\%$ of cases. Distal resection margin was less than 2 cm in $30\%$, and number of lymph node dissected was less than 12 in $31\%$. Chemotherapy was peformed in $91\%$ and most common regimen was 5-FU and leucovorine ($59\%$). The most common type of field arrangement used for the initial pelvic field was the four field box (Posterior-Right-Left) technique ($65.0\%$), and there was no AP-PA parallel opposing field used. Patient position was prone in $81.2\%$, and the boost field was used in $61.8\%$. To displace bowel outward, pressure modulating devices or bladder filling was used in $40.1\%$. Radiation dose was prescribed to isocenter in $45.3\%$ and to isodose line in 123 cases ($39.8\%$). Percent delivered dose over $90\%$ was achieved in $92.9\%$. Conclusion : We could find the Patterns of Care for the radiotherapy in Korean rectal cancer patients was similar to that of US national survey. The type of surgery and the regimen of chemotherapy were variable according to institutions and the variations of radiation dose and field arrangement were within acceptable range.

• Journal of Chest Surgery
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• v.40 no.2 s.271
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• pp.109-113
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• 2007

Background: In non-small cell lung cancer (NSCLC), malignant pleural effusion is a frequently observed com-plication, and is an important negative prognostic factor. Although many studies concerned to diagnosis and treatment of malignant pleural effusion have been performed, prognostic factors of malignant pleural effusion have rarely been investigated. This study was performed to determine the prognostic factors of malignant pleural effusion n non-small cell lung cancer. Material and Method: We evaluated 33 NSCLC patients with malignant effusion treated between January 2002 and December 2003. We analyzed possible factors: gender, age, TNM Stage, fluid analysis (pH, CEA, LDH, glucose, albumin) and treatment modality. Median survival time of each factor was calculated by Kaplan-Meier method and difference of median survival time between groups of factor compared by log-rank test. The Cox proportional hazards regression model was used to confirm the significance of prognostic factor. Results: Of the 33 patients, 23 (69.7%) patients were adenocarcinoma. The median interval of the diagnosis of lung cancer and malignant effusion was 7.3 months ($25^{th}{\sim}75^{th}:\;3.9{\sim}11.8$), and the median survival time was 3.6 months (95% Confidence Interval: $1.14{\sim}5.99$). In the univariate analysis, using the log-rank test, those with an adenocarcinoma showed a relatively longer median survival time than those of a non-adenocarcinoma (4.067 vs. 1.867 months, p=0.067) without statistical significance. In the multivariate analysis, using the Cox regression, those with a non-adenocarcinoma showed a trend of high risk of cancer death than those with an adenocarcinoma without statistical significance (Relative risk; 2.754, 95% Cl: $0.988{\sim}7.672$, p=0.053). Conclusion: We could not find an independent prognostic factor of malignant pleural effusion in NSCLC. As there was a trend of high risk of cancer death according to histology, further study will be needed.

• The Korean Journal of Nuclear Medicine Technology
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• v.26 no.1
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• pp.42-46
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• 2022

Purpose In the meantime, there have been not many samples that require dilution, and it has been difficult for the examiner to set an appropriate dilution multiple for RIA test item and report the results. Accordingly, it was judged that it was necessary to set the maximum dilution multiple for each test and to verify the upper limit of the clinical reportable range. Therefore, in this study, the maximum dilution multiple for each RIA test was set and the upper limit of the clinical reportable range was verified accordingly Materials and Methods Among all RIA tests conducted at Asan Medical Center, the study treated on 30 types of tests which also conduct the dilution test. Data from March to July 2021 were collected and analyzed. The study was conducted on samples subjected to serial dilutions such as X2, X4 or X10, X10², X10³, X10⁴, X10⁵. Results Among a total of 30 test types, 18 test types have more than 5 N values in the tolerance range of 80~120%. As a result of the verification of maximum dilution multiples, the test set to 10⁴ is 𝛼-fetoprotein and thyroglobulin, and the test set to 10³ is CA-125, CEA, and 𝛽-hCG, and the test set to 10² is Free PSA, PSA, CA15-3, SCC, Ferritin, PTH, Cortisol, and Calcitonin. Tests set to 10 include three categories: 𝛽2-Microglobulin, C-peptide, and Testosterone. Conclusion It is expected that it will contribute to improving the quality of nuclear medicine blood tests as the results of dilution experiments can be reported quickly and accurately through the verification of the clinical reportable range.