Retrospective Multicenter Analysis of Prognostic Risk Factors for One Year Recurrence in Patient With Renal Cell Carcinoma After Partial or Radical Nephrectomy: Results of Korean Renal Cancer Study Group (KRoCS) Database

Choi Changil,Kang Minyong,Seo Seong Il,Suh Jungyo,Song Cheryn,Chung Jinsoo,Kim Sung Han,Park Jae Young,Hwang Eu Chang,Jeong Chang Wook,Kwak Cheol,Kim Jung Kwon,Hong Sung-Hoo 대한의학회 2024 Journal of Korean medical science Vol.39 No.3

Background: We sought to identify prognostic risk factors for one year recurrence in patient with renal cell carcinoma (RCC) after partial or radical nephrectomy. Methods: We performed a retrospective study of 1,269 patients with RCC after partial or radical nephrectomy and diagnosed recurrence using Korean Renal Cancer Study Group (KRoCS) database between January 1991 and March 2017. Recurrence-free survival (RFS), and overall survival (OS) were calculated using the Kaplan–Meier method and multivariate Cox regression analysis were performed to evaluate independent prognostic factors for recurrence Results: The median patient age was 56 years and median follow-up period was 67 months. Multivariable analysis demonstrated BMI greater than or equal to 23 and less than 30 (vs. BMI less than 23, hazard ratio [HR]: 0.707, P = 0.020) reduced recurrence one year postoperatively. Eastern Cooperative Oncology Group performance status (ECOG PS) greater than or equal to 1 (vs. ECOG PS 0, HR: 1.548, P = 0.007), high pathological T stage (pT2 vs. pT1, HR: 2.622, P < 0.001; pT3 vs. pT1, HR: 4.256, P < 0.001; pT4 vs. pT1, HR: 4.558, P < 0.001), and tumor necrosis (vs. no tumor necrosis, HR: 2.822, P < 0.001) were independent predictive factors for early recurrence within one year in patients with RCC. Statistically significant differences on RFS and OS were found among pathological T stages (pT2 vs. pT1; pT3 vs. pT1; pT4 vs. pT1, all P < 0.001). Conclusion: This large multicenter study demonstrated ECOG PS greater than or equal to 1, high pathological T stage, tumor necrosis and BMI less than 23 were significant prognostic risk factors of early recurrence within one year in patients with RCC who underwent nephrectomy.

건설사업관리(CM)의 역할과 조직

최창일(Choi changil) 한국퍼실리티매니지먼트학회 2005 한국퍼실리티매니지먼트학회지 Vol.5 No.1

The purpose of this paper was to study a role and organization of CM. In 21th century driven by economic competitiveness, Owing to the globalization and the endless change in the construction industry. A construction market was required new, complex, complicated and competitive paradigm by a buyer. However, Up to now the definition of CM doesn’t clearly set up and an organization for CM project of Construction Company also isn’t established. So this paper was to study a role and organization of CM for the high Quality in the construction Industry.

Enhanced Li-S battery performance based on solution-impregnation-assisted sulfur/mesoporous carbon cathodes and a carbon-coated separator

Oh, Changil,Yoon, Naeun,Choi, Jaeho,Choi, Yeseul,Ahn, Seonghyeon,Lee, Jung Kyoo The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.12

<P>The widespread use of lithium-sulfur (Li-S) batteries is still hindered by the low electrochemical activity of sulfur-species, and a short cycle life owing to anode instability coupled with polysulfide shuttle effects. As a first measure to counteract these issues, a new and simple sulfur-loading method consisting of solution impregnation and subsequent melt-diffusion (IM) is demonstrated and compared to the conventional method of physical mixing followed by melt-diffusion (PM). Using the IM method, sulfur is well encapsulated and highly dispersed in conducting mesoporous carbons (MCs) that possess an ideal pore diameter (around 10 nm) and a large pore volume (∼2.8 cm<SUP>3</SUP>g<SUP>−1</SUP>). S/MC cathodes prepared by the IM method deliver much higher capacities, better rate responses and cycling stabilities up to 300 cycles (the fading rate was as low as −0.037% per cycle) with less concerns in lithium polysulfide (LPS) shuttling and impedance build up than S/MC cathodes prepared by the PM method. The S/MC cathodes prepared by the IM method has a pseudo-optimum sulfur content of 65 wt%, and when coupled with a new type of carbon-coated separator (CCS), a high areal capacity of >2.5 mA h cm<SUP>−2</SUP>is successfully achieved, combined with excellent cycling stability and rate capability.</P>

Discrete Hollow Carbon Spheres Derived from Pyrolytic Copolymer Microspheres for Li-S Batteries

Choi, Yeseul,Yoon, Naeun,Kim, Nahyeon,Oh, Changil,Park, Hyejeong,Lee, Jung Kyoo The Electrochemical Society 2019 Journal of the Electrochemical Society Vol.166 No.3

<P>Discrete hollow carbon spheres (HCSs) with a high surface-to-volume ratio and distinct conducting shell have attracted immense attention as electrode materials for batteries and supercapacitors. In this study, we developed a novel and scalable method to synthesize well-defined HCSs. The HCSs were prepared using a pyrolytic soft template of styrene/acrylic acid copolymer microspheres. Sulfur could be effectively confined inside the pores of the uniform-sized HCSs (average diameter = 320 nm, shell thickness = 40–50 nm) to produce a S/HCS-65-IM (S content = 65 wt%) Li-S cathode using a modified sulfur-loading method involving solution impregnation followed by melt-diffusion (IM). S/HCS-65-IM delivered much higher capacity and greater cycling stability over 200 cycles and showed much lower impedance build up than S/HCS-65-PM prepared via the conventional melt-diffusion of a physical mixture of sulfur powder and HCSs. The sulfur utilization of S/HCS-65-IM was further improved by more than 20% by suppressing its lithium-polysulfide shuttle effect using a carbon-coated separator (CCS). The S/HCS-65-IM cathode (with CCS) also exhibited excellent cycling stability (capacity retention of >81% after 200 cycles at 0.5 C) and high rate capability with a reduced interfacial charge transfer resistance, suggesting that S/HCS-65-IM (with CCS) is a promising cathode for Li-S batteries.</P>

Geoacoustic Inversion of Mid-Frequency Bottom Loss Data in Shallow Water off the East Coast of Korea

Lee, Changil,Cho, Sungho,Choi, Jee Woong,Shim, Taebo,Lee, Yong-Kuk IOP Publishing 2012 Japanese journal of applied physics Vol.51 No.7

Recent Trends in Transurethral Surgeries and Urological Outpatient Procedures: a Nationwide Population-based Cohort Study

김종근,Choi Changil,Ui Seok Kim,권효상,이성호,이영구,한준현 대한의학회 2020 Journal of Korean medical science Vol.35 No.38

Background: Demographic change and advances in technology affect transurethral surgery and outpatient procedures in the urologic field. There are few population-based studies that accurately assess the trend of transurethral surgery and outpatient procedures including diagnostic tests. We investigated the recent epidemiologic trends in transurethral surgeries and urological outpatient procedures from 2009 to 2016 in Korea using the entire population- based cohort. Methods: We analyzed medical service claim data of transurethral surgery, urological outpatient procedures submitted by medical service providers from the Health Insurance Review and Assessment Service from 2009 to 2016. Results: Transurethral ureter surgery increased by 134.9% from 14,635 in 2009 to 34,382 in 2016 (B = 2,698; R2 = 0.98; P < 0.001). The transurethral bladder surgery increased by 65.5% from 12,482 in 2009 to 20,658 in 2016 (B = 1,149; R2 = 0.97; P < 0.001). Over the 8-years period, there were not significant changes in transurethral prostate (B = 43; R2 = 0.04; P = 0.617) and urethral surgery (B = −12; R2 = 0.18; P = 0.289). The significantly increasing trends in cystoscopy (B = 5,260; R2 = 0.95; P < 0.001) and uroflowmetry (B = 53,942; R2 = 0.99; P < 0.001) were observed during the 8-year period. There was no difference in bladder catheterization during the 8-year period. Urodynamic study (UDS: B = −2,156; R2 = 0.77; P = 0.003) and electrical stimulation treatment (EST: B = −1,034; R2 = 0.87; P < 0.001) significantly decreased. Conclusion: In Korea, transurethral ureter surgery and transurethral bladder surgery have been continuously increasing. Transurethral prostate surgery and transurethral urethral surgery remained constant with no increase or decrease. Cystoscopy and uroflowmetry continue to increase, while UDS and EST continue to decrease.

ToF 레이더 센서 성능 검증을 위한 고정밀 측위 시스템 기반 복합 환경 구축

최명진(Myoungjin Choi),이희승(Heeseung Lee),유병연(Byeongyeon Yoo),홍지은(Jieun Hong),송문형(Moonhyong Song),김창일(Changil Kim) 대한전자공학회 2022 대한전자공학회 학술대회 Vol.2022 No.6

3D Si/C particulate nanocomposites internally wired with graphene networks for high energy and stable batteries

Kim, Jaegyeong,Oh, Changil,Chae, Changju,Yeom, Dae-Hoon,Choi, Jaeho,Kim, Nahyeon,Oh, Eun-Suok,Lee, Jung Kyoo The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.36

<▼1><P>Novel 3D particulate Si/C-IWGNs (Si/C composites internally wired with graphene networks), in which graphene networks not only provide electrical networks but generate void spaces, showed stable cycling behavior at high capacity with a small increase in electrode thickness.</P></▼1><▼2><P>It is challenging to design silicon anodes exhibiting stable cycling behavior, high volumetric and specific capacity, and low volume expansion for Li-based batteries. Herein, we designed Si/C-IWGN composites (Si/C composites internally wired with graphene networks). For this purpose, we used simple aqueous sol–gel systems consisting of varying amounts of silicon nanoparticles, resorcinol–formaldehyde, and graphene oxide. We found that a small amount of graphene (1–10 wt%) in Si/C-IWGNs efficiently stabilized their cycling behavior. The enhanced cycling stability of Si/C-IWGNs could be ascribed to the following facts: (1) ideally dispersed graphene networks were formed in the composites, (2) these graphene networks also created enough void spaces for silicon to expand and contract with the electrode thickness increase comparable to that of graphite. Furthermore, properly designed Si/C-IWGNs exhibited a high volumetric capacity of ∼141% greater than that of commercial graphite. Finally, a hybrid sample, Si–Gr, consisting of a high capacity Si/C-IWGN and graphite was prepared to demonstrate a hybrid strategy for a reliable and cost-effective anode with a capacity level required for high-energy Li-ion cells. The Si–Gr hybrid exhibited not only high capacity (800–900 mA h g<SUP>−1</SUP> at 100 mA g<SUP>−1</SUP>) but also a high electrode volumetric capacity of 161% greater than that of graphite.</P></▼2>

부유물 농도 변화에 따른 초음파 신호의 감쇠계수 측정

이찬길,최지웅,Lee, Changil,Choi, Jee Woong 한국음향학회 2014 韓國音響學會誌 Vol.33 No.1

하구와 연안은 육지와의 근접성으로 인해 강이나 하천 등에 의한 퇴적물 공급이 외해에 비해 활발하게 이루어지는 지역으로서 때로는 고농도의 부유퇴적물이 조성되기도 한다. 부유퇴적물은 외부 작용으로부터 쉽게 환경이 변하는 특성을 가지기 때문에 부유물층 탐지 및 연구를 위해 주로 음향 장비를 이용하지만 고농도 부유물 환경에서는 음파감쇠가 심하고, 이로 인해 음파의 이동 거리가 크게 감소한다. 따라서 부유물 환경에 대한 연구를 하기 위해서는 부유물 환경 특성과 주파수 변화에 따른 감쇠계수 특성을 파악하는 것이 매우 중요하다. 본 논문에서는 간이수조 내에서 고령토 가루를 이용하여 다양한 농도의 부유물을 조성한 후, 초음파 대역 (3.5, 5, 7.5 MHz)에 대한 감쇠계수를 측정하였으며, 감쇠계수 모델과 비교하였다. 감쇠계수 모델의 입력인자인 부유물의 평균입자 크기를 다양하게 변화시키며 실측값과 비교한 결과 평균 입자크기 (D50)을 기준으로 약 ${\pm}20%$ 범위 내에서 비교적 일치하였다. 이러한 오차 발생 원인은 부유물은 다양한 크기의 입자들로 구성되어 있으며, 음파 감쇠는 특정주파수에 우세한 영향을 미치는 크기의 입자분포에 영향을 받기 때문으로 판단된다. Coastal water including estuaries has distinctive environmental characteristics where sediments are transported and deposited by flowing river water, providing an environment in which fluid mud layers can be formed. Acoustic method is mostly used to detect or monitor the fluid mud layer. However, since sound propagating in this layer suffers severe attenuation, it is important to estimate the accurate attenuation coefficient for various concentrations of fluid mud layer for the successful use of the acoustic method. In this paper, measurement results of attenuation coefficient for 3.5, 5, and 7.5 MHz ultrasounds were presented. The measurements were made in a small-size water tank in which suspended sediment samples with various sediment concentrations were formed using kaolinite powder. The results were compared to the model predictions obtained by attenuation coefficient model in which the mean grain size (called as Mass-median-diameter, D50) was used as input parameter. There were reasonable agreements between measured attenuation coefficients and model outputs predicted using the particle range of D50 ${\pm}20%$. The comparison results imply that although the suspended sediments consist of various-sized particles, sound attenuation might be greatly influenced by amount of particle with a size which has a larger attenuation than that of any particle in the suspended sediments for the frequency used.

5 MHz 신호를 이용한 부유물의 농도에 따른 후방산란강도 측정

이찬길,최지웅,Lee, Changil,Choi, Jee Woong 한국음향학회 2013 韓國音響學會誌 Vol.32 No.1

연안 및 하구지역은 퇴적물의 침식, 부유, 이동이 활발하게 이루어지며, 이로 인해 유성머드와 같은 고농도의 부유퇴적물 환경이 조성된다. 유성머드는 주로 실트, 점토와 같이 매주 작은 입자들로 이루어져 있는 10 g/l 이상의 고농도 환경으로써, 유성머드의 분포 및 특성 파악을 위해 초음파와 같이 분해능이 우수한 높은 주파수 특성을 이용한 연구가 필요하다. 음파가 부유퇴적물에 의해 산란될 때, 부유퇴적물의 농도가 높아질수록 후방산란강도의 세기가 증가하지만, 점성 및 산란에 의한 감쇠도 함께 증가하기 때문에 농도에 따른 올바른 감쇠계수 보상이 요구된다. 본 논문에서는 5 MHz 주파수 특성을 바탕으로 간이 수조에서 농도에 따른 가상의 유성머드 환경을 조성한 뒤, 후방산란강도를 측정하였다. 또한 Richards의 감쇠계수 모델을 이용하여 부유물의 특성 및 농도에 따른 감쇠계수를 계산하였고, 이를 후방산란강도를 계산하는 소나방정식에 적용하여 부유물 농도에 따른 후방산란강도를 예측하였다. 그 결과 부유물에 의한 감쇠를 보상하지 않았을 경우 부유물 농도 증가에 따라 후방산란강도 값이 함께 증가하는 경향을 보이다가 일정 농도(20 g/l) 이후부터는 부유물의 농도가 증가하여도 후방산란강도가 더 이상 증가하지 않았다. 반면, 농도에 따른 감쇠계수를 보상해 주었을 경우는 부유물 농도 증가에 따라 후방산란강도가 연속적으로 증가하였다. 이러한 결과는 고농도의 부유퇴적물 환경에서 음파에 의한 산란강도를 정확히 예측하기 위해서는 부유물 농도에 따른 감쇠효과 고려가 필요함을 보여준다. The erosion, suspension, and transport of sediment frequently occur in the coastal waters and estuarine. These processes often generate the so-called fluid mud layer, which is defined as a high-concentration aqueous suspension of fine grained sediment (> 10 g/l), consisting mainly of silt and clay-size particles. Therefore the high-resolution ultrasound is mostly used to detect or monitor the fluid mud layer. Because the sound attenuation tends to increase rapidly with the suspended sediment concentration, it is necessary to consider the accurate attenuation correction to estimate the backscattering strengths from the suspended sediment layers. In this paper, the volume backscattering strengths with various suspended sediment concentrations were measured using 5-MHz ultrasound signal in a small-scale water tank. The sound attenuation due to the viscosity and scattering from suspended sediment particles was predicted by the Richard's model and applied to the sonar equation to estimate the volume backscattering strengths from the suspended sediment concentrations. For the case that the additional attenuation was not considered, the volume backscattering strengths increased to the concentration of 20 g/l, and over this point, the backscattering strengths were roughly constant. However, for the case that the attenuation due to the suspended sediment concentration was considered, the backscattering strengths increased with the concentration.