Influence of Antithrombotic Medication on the Risk of Chronic Subdural Hematoma Recurrence after Burr-Hole Surgery

Choi, Jongwook,Pyen, Jinsu,Cho, Sungmin,Kim, Jongyeon,Koo, Younmoo,Whang, Kum The Korean Neurosurgical Society 2020 Journal of Korean neurosurgical society Vol.63 No.4

Objective : Chronic subdural hematoma (CSDH) is one of the most common intracranial hemorrhages. It can be managed with a simple surgical treatment such as burr-hole trephination and drainage. However, it has a relatively high recurrence rate. The mechanisms and risk factors for the recurrence have not yet been clearly identified and studies have reported varying results. Methods : We analyzed 230 patients with CSDH who were treated with burr-hole trephination and drainage at our institution from March 2011 to March 2016. The patients were divided into recurrence and non-recurrence groups and the medical records of each group were used to analyze the risk factors associated with CSDH recurrence. Results : After burr-hole trephination and drainage, CSDH recurrence was observed in 49 (21.3%) of the 230 patients. In univariate analysis, none of the factors showed statistical significance with respect to CSDH recurrence. In multivariate analysis, preoperative antithrombotic medication was the only independent risk factor for CSDH recurrence (odds ratio, 2.407; 95% confidence interval, 1.047-5.531). Conclusion : The present study found that preoperative antithrombotic medication was independently associated with CSDH recurrence.

Temperature Analysis for Optimizing the Configuration of the Linear Cell

Jongwook Choi,Sungcho Kim,Jeong Soo Kim 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.7

The market demand of display devices is drastically increasing in the information technology age. The research on OLED (Organic Light Emitting Diodes) display with the luminescence in itself is being more paid attention than LCD (Liquid Crystal display) with the light source from the back. The vapor deposition process is most essential in manufacturing OLED display. The temperature distribution of the linear cell in this process is closely related to securing the uniformity of organic materials on the substrate. This work analyzed the temperature distribution depending on the intervals between the crucible and the heating band as well as on the amount of the heat flux from the heating band. Moreover, the roles of the water jacket and the configuration of the cover within the linear cell were examined through the temperature analysis for six configurations of the linear cell. Under the above temperature analysis, the variations in the intervals and the amount of the heat flux were considered to have an effect on building the uniform temperature distribution within the crucible. It is predicted that the water jacket and the adequate configuration of the cover will prevent the blowout and clogging phenomena, respectively. The results can be used as the fundamental data for designing the optimal linear cell.

Temperature Analysis for the Linear Cell in the Vapor Deposition Process

Choi Jongwook,Kim Sungcho,Kim Jeongsoo The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.6

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal Display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate. Its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.

Temperature Analysis for the Linear Cell in the Vapor Deposition Process

Jongwook Choi,Sungcho Kim,Jeongsoo Kim 대한기계학회 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.6

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.

Comparison of Outcomes and Recurrence in Chronic Subdural Hematoma Patients Treated by Burr-Hole Drainage with or without Irrigation

( Jongwook Choi ),( Kum Whang ),( Sungmin Cho ),( Jongyeon Kim ) 대한외상학회 2020 大韓外傷學會誌 Vol.33 No.2

Purpose: Chronic subdural hematoma (CSDH) is a common disease in elderly patients and is usually treated by burr-hole drainage. However, the optimal surgical technique for treating CSDH has not been determined. In this study, we analyzed outcomes and recurrence rates after burr-hole drainage with or without irrigation in patients with CSDH. Methods: Eighty-two CSDH patients treated with burr-hole drainage at Wonju Severance Christian Hospital from March 2015 to June 2016 were enrolled in this study. The subjects were divided into three groups based on the surgical technique performed as follows: single burr-hole drainage without irrigation (group A, n=47), single burr-hole drainage with irrigation (group B, n=14), or double burr-hole drainage with irrigation (group C, n=21). These three groups were compared with respect to clinical and radiological factors and the recurrence rate, and independent factors predicting recurrence were sought. Results: After burr-hole drainage, CSDH recurred in 15 (18.3%) of the 82 patients, and six patients (7.3%) required reoperation. More specifically, recurrence was observed in 12 patients (25.5%) in group A, one (7.1%) in group B, and two (9.5%) in group C. The number of burr-holes did not significantly affect recurrence (odds ratio [OR]=0.38; 95% confidence interval [CI]: 0.60-2.38), but irrigation had a significant effect (OR=0.20; 95% CI: 0.04-0.97). Conclusions: This study shows that irrigation during burr-hole surgery in CSDH patients significantly reduced the risk of recurrence, regardless of the number of burrholes used. We therefore recommend the use of active irrigation during burr-hole drainage surgery in CSDH patients.

Temperature Analysis for the Point-Cell Source in the Vapor Deposition Process

Jongwook Choi,Sungcho Kim,Hun Jung 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.9

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

TMS320C30을 이용한 스마트 안테나 시스템의 빔 형성 모듈 구현

김종욱(Jongwook Kim),최진우(Jinwoo Choi),최승원(Seungwon Choi) 한국통신학회 1999 한국통신학회 학술대회논문집 Vol.1999 No.7

Study on the Circuit Performance of Various Interconnect Metal Materials in the Latest Process Nodes

Moonjeong Choi,Juhwan Park,Seoungyeol Choi,Kyungbae Kwon,Yeji Lee,Wonyeong Jang,Jongwook Jeon 대한전자공학회 2023 Journal of semiconductor technology and science Vol.23 No.4

In this work, circuit-level benchmarks were performed on Copper(Cu), Tungsten(W), Cobalt(Co), Ruthenium(Ru), and Doped-multilayer-graphene (DMLG), which are various metallic material options applicable to the wire process at the late semiconductor process nodes. For the transistor, a multi-nanosheet field-effect-transistor (mNS-FET) with gate-all-around (GAA) technology was used, and the power and performance characteristics of the inverter ring oscillator circuit were analyzed assuming a 3 nm process node. In addition, various wire metal options for circuit layout were evaluated by varying fan-out number and wire length. As a result, the speed is fastest for Co and the speed reduction is smallest for DMLG in FO1 50CPP.

TPM에 기반한 iSCSI 네트워크 스토리지의 안전한 접근방안

최종욱(Jongwook Choi),박우람(Wooram Park),박찬익(Chanik Park) 한국정보과학회 2009 한국정보과학회 학술발표논문집 Vol.36 No.1D

iSCSI[1]기반의 네트워크 스토리지는 IPSec을 사용함으로써, 전송하는 데이터의 기밀성과 무결성을 보장하고, 인증을 지원하고 있다. IPSec[2][3]과 함께, iSCSI에서는 CHAP(Challenge-Handshake Authentication Protocol)[4]라는 사용자 인증 프로토콜을 제공함으로써 iSCSI Target 서버에 접근하는 사용자를 인증할 수 있다. 하지만, CHAP프로토콜은 서버에 접근하는 사용자만을 인증할 뿐, 사용자 호스트플랫폼 자체에 대한 인증은 수행하지 않는다. 이러한 상황에서 사용자 호스트에 Root-kit이나, 악의적인 소프트웨어가 설치되어 있다면 사용자가 접근하는 Target Disk의 데이터나, 사용자가 입력하는 패스워드와 같은 정보가 유출 될 수 있다. 본 논문에서는, TCG(Trusted Computing Group)에서 제안하는 Trusted Platform Module(TPM) 하드웨어 칩을 사용하여서 iSCSI로 구성된 네트워크 스토리지 환경에서 서버가 클라이언트 호스트의 플랫폼을 인증하는 방법에 대해서 디자인 하고 구현한다.

혼합형 데이타를 포함한 향상된 최적 속성 가중치 알고리즘 구현

최종욱(Jongwook Choi),권준호(Joonho Kwon),이대욱(Daewook Lee),이석호(Sukho Lee) 한국정보과학회 2008 한국정보과학회 학술발표논문집 Vol.35 No.2

클러스터링은 다양한 분야의 수많은 데이타들에 대하여 필요로 하는 지식정보를 추출하기 위한 중요한 과정으로 인식되어 왔으며, 현재까지 효율적인 클러스터링 방법에 대한 연구는 지속되고 있다. 그러나 현실 세계의 데이타는 수치형 데이타뿐만 아니라 범주형 또는 혼합된 데이타가 많이 존재하며 결국 클러스터링 기입들도 이에 대한 클러스터링을 요구하고 있다. 본 논문은 수치형 데이타를 기반으로한 OVW(Optimal Variable Weighting) 알고리즘에 대해 알아보고, 이 알고리즘의 문제점을 파악하고 분석해서 향상된 IOVW(Improved Optimal Variable Weighting) 알고리즘을 제안한다. IOVW 알고리즘은 수치형 데이타는 물론이고 범주형 및 혼합형 데이타에서도 가중치를 산출할 수 있으며, 제약식을 추가하여 보다 정확한 가중치를 얻을수 있다. 실험을 통해 두 알고리즘의 정확도를 비교하였으며 기존의 방식보다 더 향상되었다는 것을 보였다.