Hyun-Mi Bae

Prognostic factors for non-small cell lung cancer with bone metastasis at the time of diagnosis

INTRODUCTION The skeletal system is one of the most common distant sites of metastatic non-small cell lung cancer (NSCLC) which may lead to skeletal-related event (SRE). The purpose of this study was to assess the frequency of SRE and the prognostic factors of overall survival (OS) in patients presenting bone metastasis in NSCLC. METHODS Two hundred and twenty NSCLC patients with skeletal metastases at the time of diagnosis between January 2000 and August 2007 were investigated retrospectively. RESULTS Forty-seven of 110 patients (43%) without a SRE at the time of diagnosis experienced their first SRE during the follow-up. Patients with squamous cell carcinoma had a 1.8-times higher risk of short OS [95% confidence interval (CI) 1.11-2.84, p=0.016], compared with patients with non-squamous cell carcinoma, and patients treated with EGFR TKIs achieved a 50% protective effect in OS compared with patients not treated with them (95% CI 0.32-0.80, p=0.004). Patients with ECOG performance status 0-1 and single bone metastasis had a 1.8-times (95% CI 1.13-2.60, p=0.003) and 2.4-times (95% CI 1.26-4.46, p=0.008) longer OS than patients with performance status≥2 and two or more bone metastases, respectively. CONCLUSION Our study demonstrated that the frequency of SRE was common and single bone metastasis, good performance status (ECOG 0, 1), EGFR TKI treatment had good prognosis and histology of squamous cell carcinoma had bad prognosis.

Modeling and control of the single-phase photovoltaic grid-connected cascaded H-bridge multilevel inverter

This paper presents the modeling and control of the single-phase photovoltaic grid-connected five-level cascaded H-bridge multilevel inverter. For the unity power factor, the proportional and integral current controller with the duty ratio feed-forward compensation method is used. And in order to track the maximum power point and to reduce the partial shading due to stacked photovoltaic modules, each DC voltage is stably controlled to their maximum power points by dedicated voltage controllers of each H-bridge module. The modeling approach and the control loop design method are provided in this paper. The proposed control schemes are validated from experimental results of the 2-kW prototype hardware.

Current Control Design for a Grid Connected Photovoltaic/Fuel Cell DC-AC Inverter

In this paper, a current controller design method for a DC-AC inverter in a grid-connected photovoltaic or fuel cell power conditioning system (PCS) is proposed. A state feedback current controller using a sine reference function tracking algorithm and I-P(Integral-Proportional) outer DC-link voltage controller using a 120Hz notch filter are proposed to control the output current to be in-phase with the grid voltage and to regulate the input DC-link voltage. Since the analysis and design are performed in the time domain using the state equations, the current loop controller can be systematically designed for the required system specification using the pole placement technique. Also, the 120Hz notch filter for DC-link voltage regulation can enhance the dynamic performance by increasing the voltage loop bandwidth. The design guideline of each controller is provided using the stability analysis. For a design example, the prototype two-stage PCS hardware with a TMS320F2812 DSP and a real 200W solar array has been experimented to validate the proposed digital control scheme.

Digital State Feedback Current Control using Pole Placement Technique for the 42V/14V Bi-Directional DC-DC Converter Application

A digital state feedback control method for the current mode control is proposed. This approach can precisely achieve the interleaved current sharing among the converter modules. As the controller design and system analysis are performed in the time domain, the proposed method can be easily satisfied to the required converter specification using the pole placement technique. For a design example of the proposed control scheme, a parallel module bi-directional converter in a prototype 42V/14V hybrid automotive power system is implemented using a TMS320F2812 digital signal processor (DSP).

Constant resistance control of solar array regulator using average current mode control

In this paper, a single current control loop to perform the MPPT and battery charging control as well as the current sharing control for the parallel connected SAR is presented. It transforms the effective load characteristic of the SAR seen by the SA from the constant power load into the constant resistance load. Thus, the system becomes large-signally stable for the entire operation region of the SA. The proposed method is simple and flexible since it is not affected by the characteristic of the SAR. Although it uses the nonlinear control to transform the effective load characteristic of SAR, it can be easily implemented using digital controller, which may be already available for the MPPT controller without additional circuits. For the design and the stability analysis of the proposed method, the small signal analysis is performed and the Z.O.H effect is analyzed. The experimental results from a 180W prototype hardware show that the proposed control scheme has a simple implementation structure and can stabilize the system in the entire region of SA.

Digital state feedback control and feed-forward compensation for a parallel module DC-DC converter using the pole placement technique

In this paper, a simple digital control scheme for the parallel module converter is proposed using a digital state feedback control method. In this approach, the large signal average converter model is used to derive the robust tracking control algorithm of the state feedback controller instead of using the small signal modeling approach. The proposed control system can precisely achieve the interleaved current sharing and the output voltage regulation, and can achieve the systematical controller design for digital implementation using the pole placement technique. Also, a dynamic gain feed-forward control method using the operation point of the converter is proposed to improve the audio susceptibility. For a design example, a parallel module bus regulator system in the low-earth-orbit (LEO) satellite power system application, which has an input voltage step change, is implemented using a TMS320F2812 DSP.

Protein induced by vitamin K absence or antagonist-II production is a strong predictive marker for extrahepatic metastases in early hepatocellular carcinoma: a prospective evaluation

BackgroundClinicians often experience extrahepatic metastases associated with hepatocellular carcinoma (HCC), even if no evidence of intrahepatic recurrence after treatment is observed. We investigated the pretreatment predictors of extrahepatic metastases in HCC patients.MethodsPatients diagnosed with HCC without evidence of extrahepatic metastases were prospectively enrolled. We evaluated the correlation between extrahepatic metastases and pretreatment clinical variables, including serum tumor markers.ResultsA total of 354 patients were included. Seventy-six patients (21%) had extrahepatic metastases during the observation period (median, 25.3 months; range, 0.6-51.3 months). Cox regression multivariate analysis showed that serum protein induced by vitamin K absence or antagonist-II (PIVKA-II) production levels, the intrahepatic tumor stage, platelet count, and portal vein thrombosis were independent risk factors for extrahepatic metastases. Patients with a PIVKA-II production ≥ 300 mAU/mL had a 2.7-fold (95% confidence interval; 1.5-4.8; P < 0.001) and 3.7-fold (95% confidence interval; 2.0-6.6; P < 0.001) increased risk for extrahepatic metastases after adjustment for stage, platelet count, alpha-fetoprotein ≥ 400 ng/mL, and portal vein thrombosis according to the AJCC and BCLC staging systems, respectively.ConclusionPIVKA-II production levels might be a good candidate predictive marker for extrahepatic HCC metastases, especially in patients with smaller and/or fewer tumors in the liver with in stages regardless of serum alpha-fetoprotein.

A simplified series-parallel structure for the regulated peak power tracking (RPPT) system

Regulated peak power tracking (RPPT) systems such as the series structure and the parallel structure are commonly used in satellite space power systems. However, this structure processes the solar array power or the battery power to the load through two regulators during one orbit cycle, which reduces the energy transfer efficiency. The series-parallel structure for the RPPT system can improve the power conversion efficiency, but an additional regulator increases the cost, size and weight of the system. In this paper, a simplified series-parallel space power system that consists of two regulators is proposed. The proposed system achieves similar energy transfer efficiency with the series-parallel structure by adding one switch to the series structure, which reduces the cost, size and the weight. A single digital signal processor (DSP) is used to control all of the required functions, such as current sharing for the parallel module converter, load voltage regulation, solar array stabilizing, maximum power point tracking (MPPT) and the system operation algorithm of the proposed system. The large signal stability analysis is provided to understand the four main modes of system operation. In order to compare the energy efficiency with a series structure, the simulations are performed and the results are analyzed. The proposed structure saves 11% energy compared to the series structure. Experimental verifications are performed using prototype hardware with a TMS320F2812 DSP and 200 W solar arrays.

Hematopoietic Stem Cell Transplantation after Posttransplant Lymphoproliferative Disorder

A 16-yr-old girl received liver transplantation for fulminant hepatitis. Aplastic anemia developed, and she received hematopoietic stem cell transplantation (HSCT). Eleven months after liver transplantation, abdominal lymph node enlargement and colon ulcers were observed, and colon biopsy showed posttransplant lymphoproliferative disorder (PTLD). Immunosuppression reduction was attempted, but it produced no therapeutic effect. Fourteen months after liver transplantation, she received a second HSCT due to engraftment failure, and PTLD resolved completely. The second HSCT can serve as cellular therapy for PTLD.

Development of software testbed using parametric design approaches for a series hybrid military vehicle

This paper deals with the component sizing of a series hybrid electric vehicle (HEV). Since the component sizes are interrelated with the power-train structures and power control algorithm, the optimal sizing cannot be determined in a simple manner. Thus, in order to simplify the sizing problem for the HEV, this paper presents parametric design approaches which identifies the sizing effects with respect to control frequency changes of each component based on a low pass filtered power control algorithm. By using the functional simulation model with Matlab/Simulink, the proposed methods can easily and rapidly calculate the power and energy capacity of each component from the heuristic rules. The component size for designing the system is determined by a weighted cost function including the mass, volume and efficiency. This paper shows the design procedure of the proposed approaches for a 6×6 series hybrid electric armored wheeled vehicle.