Ureteral stenting can be a negative predictor for successful outcome following shock wave lithotripsy in patients with ureteral stones

강동혁,조강수,함원식,정두용,권종규,최영득,이주용 대한비뇨의학회 2016 Investigative and Clinical Urology Vol.57 No.6

Purpose: To evaluate ureteral stenting as a negative predictive factor influencing ureteral stone clearance and to estimate the probability of one-session success in shock wave lithotripsy (SWL) patients with a ureteral stone. Materials and Methods: We retrospectively reviewed the medical records of 1,651 patients who underwent their first SWL. Among these patients, 680 had a ureteral stone measuring 4–20 mm and were thus eligible for our study. The 57 patients who underwent ureteral stenting during SWL were identified. Maximal stone length (MSL), mean stone density (MSD), skin-to-stone distance (SSD), and stone heterogeneity index (SHI) were determined by pre-SWL noncontrast computed tomography. Results: After propensity score matching, 399 patients were extracted from the total patient cohort. There were no significant differences between stenting and stentless groups after matching, except for a higher one-session success rate in the stentless group (78.6% vs. 49.1%, p=0.026). In multivariate analysis, shorter MSL, lower MSD, higher SHI, and absence of a stent were positive predictors for one-session success in patients who underwent SWL. Using cutoff values of MSL and MSD obtained from receiver operator curve analysis, in patients with a lower MSD (≤784 HU), the success rate was lower in those with a stent (61.1%) than in those without (83.5%) (p=0.001). However, in patients with a higher MSL (>10 mm), the success rate was lower in those with a stent (23.6%) than in those without (52.2%) (p=0.002). Conclusions: Ureteral stenting during SWL was a negative predictor of one-session success in patients with a ureteral stone.

대용량 문서 데이터베이스를 위한 효율적인 점진적 문서 클러스터링 기법

강동혁,주길홍,이원석,Kang, Dong-Hyuk,Joo, Kil-Hong,Lee, Won-Suk 한국정보처리학회 2003 정보처리학회논문지D Vol.10 No.1

With the development of the internet and computer, the amount of information through the internet is increasing rapidly and it is managed in document form. For this reason, the research into the method to manage for a large amount of document in an effective way is necessary. The document clustering is integrated documents to subject by classifying a set of documents through their similarity among them. Accordingly, the document clustering can be used in exploring and searching a document and it can increased accuracy of search. This paper proposes an efficient incremental cluttering method for a set of documents increase gradually. The incremental document clustering algorithm assigns a set of new documents to the legacy clusters which have been identified in advance. In addition, to improve the correctness of the clustering, removing the stop words can be proposed and the weight of the word can be calculated by the proposed TF$\times$NIDF function. 컴퓨터의 발전과 인터넷의 급속한 발전으로 정보의 양이 폭발적으로 증가하게 되었고 이러한 방대한 양의 정보들은 대부분 문서 형태로 관리되고 있으며, 문서 단위별 표현된 많은 정보들을 효과적으로 관리하고 검색하기 위한 방법의 연구가 필요하게 되었다. 문서 클러스터링은 문서간의 유사도를 바탕으로 서로 연관된 문서들을 군집화하여 문서들을 주제별로 통합하는 방법으로 대용량의 문서들을 자동으로 분류하고, 검색하는 데 있어서 검색의 정확성을 증대시킬 수 있다. 본 논문에서는 새로운 문서의 추가나 기존문서의 삭제로 인하여 군집화 대상이 되는 문서 집합이 점진적으로 변화하는 환경을 위한 점진적 문서 클러스터링 알고리즘을 제안한다. 점진적 문서 클러스터링 알고리즘은 새로운 문서가 추가되었을 경우 문서 전체를 다시 클러스터링하지 않고, 이미 생성된 클러스터들의 구조를 적극적으로 변화시킴으로써 높은 효율성을 제공할 수 있다. 또한, 문서 클러스터링의 정확도를 높이기 위하여 통계적인 기법으로 불용어를 판별하여 제거하는 알고리즘을 제안하고, 문서 클러스터링에서 정확한 단어가중치 산출을 위해 TF$\times$IDF 공식을 수정한 TF$\times$NIDF 공식을 제안한다.

Analysis of Prescriptions of Alpha-Blockers and Phosphodiesterase 5 Inhibitors from the Urology Department and Other Departments

강동혁,이주용,정재훈,조희주,조정만,문홍상,김용태,유탁근,최홍용,박해영,이승욱 대한배뇨장애요실금학회 2011 International Neurourology Journal Vol.15 No.4

Purpose: We analyzed the prescriptions of alpha-blockers and phosphodiesterase 5 inhibitors (PDE5Is) in the urology department as well as in other departments of the general hospital. Methods: We investigated the frequency of prescription of alpha-blockers and PDE5Is from 3 general hospitals from January 1, 2007 to December 31, 2009. For alpha-blockers, data were collected from patients to whom alpha-blockers were prescribed from among patients recorded as having benign prostatic hyperplasia according to the 5th Korean Standard Classification of Diseases. For PDE5Is, data were collected from patients to whom PDE5Is were prescribed by the urology department and by other departments. Alpha-blockers were classified into tamsulosin, alfuzosin, doxazosin, and terazosin, whereas PDE5Is were classified into sildenafil, tadalafil, vardenafil, udenafil, and mirodenafil. Results: Alpha-blockers were prescribed to 11,436 patients in total over 3 years, and the total frequency of prescriptions was 68,565. Among other departments, the nephrology department had the highest frequency of prescription of 3,225 (4.7%), followed by the cardiology (3,101, 4.5%), neurology (2,576, 3.8%), endocrinology (2,400, 3.5%), pulmonology (1,102, 1.6%), and family medicine (915, 1.3%) departments in order. PDE5Is were prescribed to 2,854 patients in total over 3 years, and the total frequency of prescriptions was 10,558. The prescription frequency from the urology department was 4,900 (46.4%). Among other departments, the endocrinology department showed the highest prescription frequency of 3,488 (33.0%), followed by the neurology (542, 5.1%), cardiology (467, 4.4%), and family medicine (407, 3.9%) departments in order. Conclusions: A high percentage of prescriptions of alpha-blockers and PDE5Is were from other departments. For more specialized medical care by urologists is required in the treatment of lower urinary tract symptoms and erectile dysfunction.

LOx와 Kerosene을 추진제로 하는 1열 핀틀 분사기의 고압 연소성능 특성에 관한 연구

강동혁,김종규,유철성,고영성 항공우주시스템공학회 2022 항공우주시스템공학회지 Vol.16 No.5

The pintle injector has many advantages in the key characteristics of a liquid rocket engine, such as combustion stability, combustion efficiency, and wide range of comprehensive thrust control, design and manufacture, and test fired under supercritical conditions. The pintle injector is manufactured with a rectangular, single-row orifice for thrust control and production considerations. In order to verify the combustion performance of the pintle injector and its potential as a commercial injector, the combustion characteristics were analyzed by varying the TMR (Total Momentum Ratio) and BF (Blockage Factor). The result of the hot firing test showed that the heat flux increased as TMR increased, and it confirmed that the characteristic velocity efficiency was more affected by BF than TMR. Suppose a single-row pintle injector with efficiency characteristics insensitive to changes in TMR can achieve high efficiency at low fuel differential pressure conditions. In that case, the variable pintle injector’s design flexibility can be increase.

The Possibilities as a Prediction Tool for Cancer Research of Big Data: Comparison of Incidence Rate of Korean Major Male and Urologic Cancers and Trend Scores

강동혁,조강수,함원식,최영득,이주용 대한비뇨기종양학회 2015 대한비뇨기종양학회지 Vol.13 No.1

Purpose: To examine the trend, and investigated the possibilities as a prediction tool by choosing the trend score about male and urologic cancers have the high incidence rate. Materials and Methods: We selected 5 major male and 3 major urologic cancers for past 3 years (from 2010 to 2012) and examined the incidence rate, and using Naver and Google trend, the rate of cancer incidence was compared with the trend score during the same period. Results: From 2010 to 2012, the greatest occurrence of the cancer to males was the stomach cancer, followed by colon, lung, liver, and prostate cancer. In the urologic field, the prostate cancer was the first one, followed by kidney and bladder cancer. In 2010 to 2012, the Naver trend score was 32 for stomach and colon cancers, 31 for lung cancers, 20 for liver cancers, and 19 for prostate cancers, which index were corresponded with the order of incidence rate. Though the Google trend score for prostate cancer was not found, the average was 9 for stomach cancer, 8 for colon cancer, 6 for lung cancer, 4 for liver cancer, which index were corresponded with the order of incidence rate. In 2013 and 2014, the figure of prostate cancer was grown and exceeded liver cancer. Conclusions: In the trend score, the index of the prostate cancer shows continuing increase, and, from the results, urologists should recognize the importance of the study on the prostate cancer such as management, prevention, and treatment of the prostate cancer.

차폐블록 제작과정의 전산화를 통한 업무개선

강동혁,정도형,강동윤,전용궁,황재웅,Kang, Dong Hyuk,Jeong, Do Hyeong,Kang, Dong Yoon,Jeon, Young Gung,Hwang, Jae Woong 대한방사선치료학회 2013 대한방사선치료학회지 Vol.25 No.1

Purpose: Introducing CR (Computed Radiography) system created a process of printing therapy irradiation images and converting the degree of enlargement. This is to increase job efficiency and contribute to work improvement using a computerized method with home grown software to simplify this process, work efficiency. Materials and Methods: Microsoft EXCEL (ver. 2007) and VISUAL BASIC (ver. 6.0) have been used to make the software. A window for each shield block was designed to enter patients' treatment information. Distances on the digital images were measured, the measured data were entered to the Excel program to calculate the degree of enlargement, and printouts were produced to manufacture shield blocks. Results: By computerizing the existing method with this program, the degree of enlargement can easily be calculated and patients' treatment information can be entered into the printouts by using macro function. As a result, errors in calculation which may occur during the process of production or errors that the treatment information may be delivered wrongly can be reduced. In addition, with the simplification of the conversion process of the degree of enlargement, no copy machine was needed, which resulted in the reduction of use of paper. Conclusion: Works have been improved by computerizing the process of block production and applying it to practice which would simplify the existing method. This software can apply to and improve the actual conditions of each hospital in various ways using various features of EXCEL and VISUAL BASIC which has already been proven and used widely.

서보 밸브와 스프링 댐퍼 방식의 가변 핀틀 분사기 헤드부 설계 및 작동성 검증 수류시험

강동혁,황도근,한상훈,허성찬,이병용,주성민,김종규 한국추진공학회 2024 한국추진공학회지 Vol.28 No.2

In this paper, the variable pintle injector controls the flow rate by adjusting the area of the pintle orifice and the annulus ring while the piston sleeve moves. The variable pintle injector heads of the servo valve and spring damper method was designed and manufacture with the same design specification. It was partially made of polycarbonate material to verify the operating performance. The varialbe pintle injector head consists of pintle, piston sleeve, spring, stopper, head case and various gaskets, and cold flow test will be conducted to verify the operating performance. In the cold flow test, it was confirmed that the design flow rate and the ability to maintain an appropriate differential pressure for flow changes based on thrust. This paper describes the configuration of variable pintle injectors of servo valve and spring damper, operation mechanisms and cold flow test results.

Graphitic Pyropolymer-Based Nanosubstrate for Rechargeable Mg Metal Batteries

강동혁,하손,윤영수 한국고분자학회 2020 한국고분자학회 학술대회 연구논문 초록집 Vol.45 No.2

Demagnetization Detection for IPM-type BLDCMs According to Irreversible Demagnetization Patterns and Pole–Slot Coefficients

강동혁,김형규,박준규,현승호,허진 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

This paper proposes a method for detecting irreversible demagnetization using the harmonic analysis of back electromotive force (BEMF) in interior permanent magnet-type brushless DC motors. First, demagnetization patterns, such as equality, inequality, and weighted demagnetizations, are defined and classified by considering the possibility of demagnetization resulting from motor operating characteristics. Second, an available diagnostic model for the harmonic analysis of BEMFs is defined according to pole–slot coefficients because the characteristics of BEMFs under demagnetization conditions are affected by the combination of poles and slots. Third, BEMFs and their harmonic components under normal and demagnetization conditions are analyzed through simulation and experiment to verify the proposed demagnetization detection technique.

실물형 연소기 재생냉각 연소시험을 위한 설비개선 및 연소기 장착 수류시험

강동혁,임병직,이광진,한영민,최환석 한국항공우주학회 2007 한국항공우주학회 학술발표회 논문집 Vol.- No.-