• The Korean Journal of Physiology and Pharmacology
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• 제2권3호
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• pp.369-376
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• 1998

This report shows that hydroxyl radical, generated by a Fenton reaction involving adenosine $5'-diphosphate/Fe^{2+}$ complex ($5-15\;{\mu}M$) and $H_2O_2$ ($2\;{\mu}M$), induced differentiation of HL-60 cells in a dose- and time-dependent manner. This is evidenced by the increases in 12-O-tetradecanoylphorbol 13-acetate- and fMLP-stimulated superoxide production capability. The cells exposed to hydroxyl radical for defined periods (24∼96 hr) continued to differentiate even after the hydroxyl radical generating system had been removed. The differentiated cells displayed fMLP-stimulated calcium mobilization and increased expression of myeloid-specific antigen CD11b and CD14. The extent of the differentiation was markedly reduced by desferrioxamine ($100\;{\mu}M$), dimethylthiourea (5 mM), N,N'-diphenyl-1,4-phenylenediamine ($2\;{\mu}M$), and N-acetyl-L-cysteine (5 mM). The induction of differentiation by hydroxyl radical was enhanced by 3-isobutyl-1-methylxanthine ($200\;{\mu}M$) and Ro-20-1724 ($8\;{\mu}M$), and inhibited by dipyridamole (2 ${\mu}M$). These results suggest that hydroxyl radicals may induce commitment of HL-60 cells to differentiate into more mature cells of myelomonocytic lineage through specific signal-transduction pathway that is modulated by phosphodiesterase inhibitors.

• 보건행정학회지
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• 제31권3호
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• pp.280-291
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• 2021

Background: Based on the fact that the Korea Medical Dispute Mediation and Arbitration Agency is a public institution established by social demands for medical disputes, this study reviews the publicness of public organization and discusses its policy implications. Methods: Through Moore's strategic triangle, which consists of legitimacy and support, public value and operational capacity, the process of creating public value is examined. For the analysis, case studies were conducted using related literature data from 2012, when the agency was established, to the present. Results: As a result of the analysis, first, the related law examined in the operational capability has been revised dozens of times, but the revised law has its own contradictions and limitations. The human resource system is also being improved, but there is a problem with the fairness and reliability of the arbitration process, especially due to the limitations of the appraiser system. Second, in terms of legitimacy and support, a regional gap occurred despite efforts to improve accessibility through the expansion of the organization. And the arbitration agency failed to reconcile conflicts caused by stakeholders' perception of each other as a trade-off relationship. Third, the public value result shows that, despite many explicit (statistical) achievements, citizens' use of the past dispute resolution means (litigation) has not decreased. Likewise, the perception of value makers (citizens) is important for creating public value as an invisible result, but it has not yet been formally investigated, so the performance can not be recognized. Conclusion: While the organization's efforts for continuous change and improvement are encouraging, it is not perceived as a better means of resolving disputes and improving quality of services. Therefore, it is necessary to reconsider the institutional design centered on value creators.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2016-2029
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• 2023

Accurate prediction of critical illness is significant for ensuring the lives and health of patients. The selection of indicators affects the real-time capability and accuracy of the prediction for critical illness. However, the diversity and complexity of these indicators make it difficult to find potential connections between them and critical illnesses. For the first time, this study proposes an indicator analysis model to extract key indicators from the preoperative and intraoperative clinical indicators and laboratory results of critical illnesses. In this study, preoperative and intraoperative data of heart failure and respiratory failure are used to verify the model. The proposed model processes the datum and extracts key indicators through four parts. To test the effectiveness of the proposed model, the key indicators are used to predict the two critical illnesses. The classifiers used in the prediction are light gradient boosting machine (LightGBM) and eXtreme Gradient Boosting (XGBoost). The predictive performance using key indicators is better than that using all indicators. In the prediction of heart failure, LightGBM and XGBoost have sensitivities of 0.889 and 0.892, and specificities of 0.939 and 0.937, respectively. For respiratory failure, LightGBM and XGBoost have sensitivities of 0.709 and 0.689, and specificity of 0.936 and 0.940, respectively. The proposed model can effectively analyze the correlation between indicators and postoperative critical illness. The analytical results make it possible to find the key indicators for postoperative critical illnesses. This model is meaningful to assist doctors in extracting key indicators in time and improving the reliability and efficiency of prediction.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2004년도 제29회 추계학술대회 발표논문집
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• pp.158-161
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• 2004

방사선 치료의 핵심 장비인 선형가속기의 10년간 관리 기록을 분석하여 효율적인 관리 지표로 활용하고자한다. 장비의 장애 요인을 다각적으로 분석하기위해 고장 원인을 치료기 부위별로 세분했고 각각이 미치는 영향을 세 단계로 구분하여 조사했다. 또한 장비 사용량이 고장에 미치는 영향을 분석하기 위해 년도별 치료 환자수와 고장건수, 중요 부속의 평균 수명 등을 분석했다. 10년간 전체 고장건수는 587건 이였으며 이중 조사헤드부의 고장이 20%를 자치해 가장 높게 나타났으며 고장이 미치는 영향에 의한 분석에서는 일시적 장애해 당하는 중간 정도의 고장이 41%를 차지해 가장 높게 나타났다. 장애 영향이 가장 큰 조사 불가능 상태의 고장은 가속부에서 49%로 가장 높게 나타났으며 고장과 관련된 지표는 사용연수 및 치료건수와 밀접한 관계를 나타냈다. 중요 부속의 평균 수명은 클라이스트론과 싸이라트론의 경우 치료건수가 증가함에 따라 교체 주기가 빨라져 각각 제조사 권고치의 42%, 83% 수준이였다. 안정적인 치료서비스 제공을 위해서는 사용 연수가 증가함에 따라 장비 관리의 필요성이 더욱 중요시 되어야하며 10년간 장비 관리기록을 통해 얻은 각종 지표가 향후 효율적 관리의 좋은 지침이 될 것으로 사료된다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.315-319
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• 1996

We have developed a prototype patient monitoring system including module-based bedside units, interbed network, and central stations. A bedside unit consists of a color monitor and a main CPU unit with peripherals including a module controller. It can also include up to 3 module cases and 21 different modules. In addition to the 3-channel recorder module, six different physiological parameters of ECG, respiration, invasive blood pressure, noninvasive blood pressure, body temperature, and arterial pulse oximetry with plethysmogaph are provided as parameter modules. Modules and a module controller communicate with up to 1Mbps data rate through an intrabed network based on RS-485 and HDLC protocol. Bedside units can display up to 12 channels of waveforms with any related numeric informations simultaneously. At the same time, it communicates with other bedside units and central stations through interbed network based on 10Mbps Ethernet and TCP/IP protocol. Software far bedside units and central stations fully utilizes gaphical user interface techniques and all functions are controlled by a rotate/push button on bedside unit and a mouse on central station. The entire system satisfies the requirements of AAMI and ANSI standards in terms of electrical safety and performances. In order to accommodate more advanced data management capabilities such as 24-hour full disclosure, we are developing a relational database server dedicated to the patient monitoring system. We are also developing a clinical workstation with which physicians can review and examine the data from patients through various kinds of computer networks far diagnosis and report generation. Portable bedside units with LCD display and wired or wireless data communication capability will be developed in the near future. New parameter modules including cardiac output, capnograph, and other gas analysis functions will be added.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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• pp.45-45
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• 2003

The aim of this study was the characterization and performance validation of new prototype avalanche photodiode (APD) arrays for positron emission tomography (PET). Two different APD array prototypes (noted A and B) developed by Radiation Monitoring Device (RMD) have been investigated. Principal characteristics of the two APD array were measured and compared. In order to characterize and evaluate the APD performance, capacitance, doping concentration, quantum efficiency, gain and dark current were measured. The doping concentration that shows the impurity distribution within an APD pixel as a function of depth was derived from the relationship between capacitance and bias voltage. Quantum efficiency was measured using a mercury vapor light source and a monochromator used to select a wavelength within the range of 300 to 700 nm. Quantum efficiency measurements were done at 500 V, for which the APD gain is equal to one. For the gain measurements, a pencil beam with 450 nm in wavelength was illuminating the center of each pixel. The APD dark currents were measured as a function of gain and bias. A linear fitting method was used to determine the value of surface and bulk leakage currents. Mean quantum efficiencies measured at 400 and 450 nm were 0.41 and 0.54, for array A, and 0.50 and 0.65 for array B. Mean gain at a bias voltage of 1700 V, was 617.6 for array A and 515.7 for type B. The values based on linear fitting were 0.08${\pm}$0.02 nA 38.40${\pm}$6.26 nA, 0.08${\pm}$0.0l nA 36.87${\pm}$5.19 nA, and 0.05${\pm}$0.00 nA, 21.80${\pm}$1.30 nA in bulk surface leakage current for array A and B respectively. Results of characterization demonstrate the importance of performance measurement validating the capability of APD array as the detector for PET imaging.

• Asian Pacific Journal of Cancer Prevention
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• 제16권15호
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• pp.6469-6475
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• 2015

Background: Diffusion-weighted magnetic resonance imaging (DWI) makes it possible to detect malignant tumors based on the diffusion of water molecules. It is uncertain whether DWI is more useful than positron emission tomography-computed tomography (PET-CT) for distinguishing benign from malignant mediastinal tumors and mass lesions. Materials and Methods: Sixteen malignant mediastinal tumors (thymomas 7, thymic cancers 3, malignant lymphomas 3, malignant germ cell tumors 2, and thymic carcinoid 1) and 12 benign mediastinal tumors or mass lesions were assessed in this study. DWI and PET-CT were performed before biopsy or surgery. Results: The apparent diffusion coefficient (ADC) value ($1.51{\pm}0.46{\times}10^{-3}mm^2/sec$) of malignant mediastinal tumors was significantly lower than that ($2.96{\pm}0.86{\times}10^{-3}mm^2/sec$) of benign mediastinal tumors and mass lesions (P<0.0001). Maximum standardized uptake value (SUVmax) ($11.30{\pm}11.22$) of malignant mediastinal tumors was significantly higher than that ($2.53{\pm}3.92$) of benign mediastinal tumors and mass lesions (P=0.0159). Using the optimal cutoff value (OCV) $2.21{\times}10^{-3}mm^2/sec$ for ADC and 2.93 for SUVmax, the sensitivity (100%) by DWI was not significantly higher than that (93.8%) by PET-CT for malignant mediastinal tumors. The specificity (83.3%) by DWI was not significantly higher than that (66.7%) for benign mediastinal tumors and mass lesions. The accuracy (92.9%) by DWI was not significantly higher than that (82.1%) by PET-CT for mediastinal tumors and mass lesions. Conclusions: There was no significant difference between diagnostic capability of DWI and that of PET-CT for distinguishing mediastinal tumors and mass lesions. DWI is useful in distinguishing benign from malignant mediastinal tumors and mass lesions.

• Korean Journal of Acupuncture
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• 제32권4호
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• pp.169-176
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• 2015

목적 : 한의학에서 골절이나 신장질환에 사용되어 왔던 골쇄보열수추출물 약침액이 항염증 및 항산화활성에 대한 효능이 있는지를 연구하고자 한다. 방법 : 골쇄보열수추출물 약침액이 세포독성에 미치는 영향을 관찰하기 위하여 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay를 실시하였다. 골쇄보열수추출물 약침액이 항염증효능에 미치는 영향을 관찰하기 위하여 lipopolysaccharide(LPS)로 유도된 RAW264.7 대식세포에서의 산화질소(NO) 및 프로스타글란딘($PGE_2$) 생성 억제력을 관찰하였다. 또한 골쇄보열수추출물 약침액이 항산화활성에 미치는 영향을 관찰하기 위하여 1,1-diphenyl-2-pciry hydrazyl(DPPH) radical 소거능을 관찰하였다. 결과 : 골쇄보열수추출물 약침액은 $50{\sim}400{\mu}g/ml$ 농도에서 세포독성이 나타나지 않았다. 골쇄보열수추출물 약침액은 200 및 $400{\mu}g/ml$ 농도에서 LPS로 유도된 NO 및 $PGE_2$ 생성을 통계학적으로 유의하게 감소시켰다. 골쇄보추출물은 $50{\sim}400{\mu}g/ml$ 농도에서 DPPH 소거능을 관찰한 결과 농도의존적으로 활성화되는 것을 관찰하였다. 결론 : 골쇄보열수추출물 약침액은 항염증 및 항산화 효과가 있을 것으로 사료된다.

• 한국방사선학회논문지
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• 제12권6호
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• pp.713-718
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• 2018

많은 선행 연구에서는 무연 차폐재를 제작하기 위하여 몬테카를로 시뮬레이션을 통해 방사선 차폐 능력과 경량화에 대한 가능성을 제시하고 있다. 하지만, 이는 바인더 및 미세 기공에 대한 구현이 어렵기에 제품화 공정에 필요한 정보를 충분히 제공하지 못하는 실정이다. 이에 본 연구에서는 제품화 공정에 요구되는 겔 페이스트에 대한 정보를 사전에 제공하기 위하여 스크린 프린팅 공법을 활용하여 충전율에 따른 방사선 차폐 능력에 대한 결과를 제시하였다. 본 연구에서는 방사선 차폐 능력을 평가하기 위해 IEC 61331-1: 2014와 KS A 4025에 부합하도록 실험 환경을 설계하였으며, 방사선 조사 조건은 KS A 4021 규격을 준용하여 총 여과 2.0 mmAl로 여과된 100 kVp를 이용하였다. 본 연구 결과, TVL를 기준으로 Pb $1270{\mu}m$, $BaSO_4$ $3035{\mu}m$, $Bi_2O_3$ $1849{\mu}m$, $WO_3$ $2631{\mu}m$에서 근사한 값으로 분석되었다. 또한, 충전율은 $BaSO_4$ 38.6%, $Bi_2O_3$ 27.1%, $WO_3$ 30.15%로 분석되었다. 하지만, 차후 저온고압 성형을 적용한다면 충전율을 높이면서도 기공률을 낮춤으로서 방사선 차폐 능력의 개선이 충분히 가능할 것으로 기대된다.

• Korean Journal of Radiology
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• 제24권4호
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• pp.338-348
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• 2023

Objective: Patients with a history of ischemic stroke are at risk for a second ischemic stroke. This study aimed to investigate the relationship between carotid plaque enhancement on perfluorobutane microbubble contrast-enhanced ultrasonography (CEUS) and future recurrent stroke, and to determine whether plaque enhancement can contribute to risk assessment for recurrent stroke compared with the Essen Stroke Risk Score (ESRS). Materials and Methods: This prospective study screened 151 patients with recent ischemic stroke and carotid atherosclerotic plaques at our hospital between August 2020 and December 2020. A total of 149 eligible patients underwent carotid CEUS, and 130 patients who were followed up for 15-27 months or until stroke recurrence were analyzed. Plaque enhancement on CEUS was investigated as a possible risk factor for stroke recurrence and as a possible adjunct to ESRS. Results: During follow-up, 25 patients (19.2%) experienced recurrent stroke. Patients with plaque enhancement on CEUS had an increased risk of stroke recurrence events (22/73, 30.1%) compared to those without plaque enhancement (3/57, 5.3%), with an adjusted hazard ratio (HR) of 38.264 (95% confidence interval [CI]:14.975-97.767; P < 0.001) according to a multivariable Cox proportional hazards model analysis, indicating that the presence of carotid plaque enhancement was a significant independent predictor of recurrent stroke. When plaque enhancement was added to the ESRS, the HR for stroke recurrence in the high-risk group compared to that in the low-risk group (2.188; 95% CI, 0.025-3.388) was greater than that of the ESRS alone (1.706; 95% CI, 0.810-9.014). A net of 32.0% of the recurrence group was reclassified upward appropriately by the addition of plaque enhancement to the ESRS. Conclusion: Carotid plaque enhancement was a significant and independent predictor of stroke recurrence in patients with ischemic stroke. Furthermore, the addition of plaque enhancement improved the risk stratification capability of the ESRS.