• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1803-1806
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• 2013

Purpose: Carbohydrate antigen (CA) 242 is inversely related to prognosis in many cancers. However, few data regarding CA 242 in esophageal cancer (EC) are available. The aim of this study was to determine the prognostic value of CA 242 and propose an optimum cut-off point in predicting survival difference in patients with esophageal squamous cell carcinoma (ESCC). Methods: A retrospective analysis was conducted of 192 cases. A receiver operating characteristic (ROC) curve for survival prediction was plotted to verify the optimum cuf-off point. Univariate and multivariate analyses were performed to evaluate prognostic parameters for survival. Results: The positive rate for CA 242 was 7.3% (14/192). The ROC curve for survival prediction gave an optimum cut-off of 2.15 (U/ml). Patients with CA 242 ${\leq}$ 2.15 U/ml had significantly better 5-year survival than patients with CA 242 >2.15 U/ml (45.4% versus 22.6%; P=0.003). Multivariate analysis showed that differentiation (P=0.033), CA 242 (P=0.017), T grade (P=0.004) and N staging (P<0.001) were independent prognostic factors. Conclusions: Preoperative CA 242 is a predictive factor for long-term survival in ESCC, especially in nodal-negative patients. We conclude that 2.15 U/ml may be the optimum cuf-off point for CA 242 in predicting survival in ESCC.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.49-55
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• 2015

In this study, among in various scenarios of the duration degradation of the fuel cell, countermeasures for the cathode carbon carrier oxidation and the deactivation of catalyst by hydrogen / air interface formation have been studied. so the system was applied to the air cutoff valve. In terms of the component, the cold start performance, electrical stability, the airtight performance were mainly designed and their performance was confirmed. And in terms of the system, the air electrode flow is blocked off, so the oxygen concentration drops when system is powered off, As a result, By reducing unit cell voltage which affect the durability of the fuel cell reached up to 0.8V, the improved durability of the fuel cell was confirmed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2198-2203
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• 2008

Hydrogen which can be produced through reforming process of hydrocarbon fuel is supplied into anode side of fuel cell system. In the fuel cell, only 70% of hydrogen is consumed through electrochemical reaction and 30% hydrogen passed by as anode off gas. When electrical output of fuel cell is within range of 1.0 to 3.0kW, burner for the reformer uses only anode off gas. And it uses mixture gas of anode off gas and LNG within range of 3.5 to 5.0kW in electrical output. CHEMKIN 4.1 program's Premixed code was used for calculating the properties of each gas. Results show that burning velocity and adiabatic flame temperature are 34.4cm/s, 1681.7K at equivalence ratio 0.8 within range of 1.0kW to 3.0kW and for cases of 3.5kW, 5.0kW, of electrical output, burning velocity and adiabatic flame temperature represent 30.5, 29.8cm/s and 1722.8, 1750K respectively. CO shows the lowest emission index at equivalence ratio 0.8 and NOx reveals the highest emission index at equivalence ratio 1.

• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.27-38
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• 2022

Urban air mobility (UAM) has recently attracted lots of attention as a solution to urban centralization and global warming. Electric vertical take-off and landing (eVTOL) is a concept that emerges as one of the promising and clean technologies for UAM. There are two difficult challenges for eVTOL aircraft to solve. One is how to improve the weight efficiency of aircraft, and the other is how to complete long-range missions for UAM's flight scenarios. To approach these challenges, we propose a consolidated concept design of battery-fuel cell hybrid tiltrotor aircraft with a liquid hydrogen (LH₂) fuel tank. The efficiency of a battery-fuel cell hybrid powertrain system on the designed eVTOL aircraft is compared to that of a battery-only powertrain system. This paper shows how much payload can increase and the flight scenario can be improved by hybridizing the battery and fuel cell and presenting a detailed concept of a cryogenic storage tank for LH₂.

• Journal of Yeungnam Medical Science
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• 제29권1호
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• pp.14-18
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• 2012

Background: The purpose of this study was to differentiate chromophobe renal cell carcinoma and clear cell renal cell carcinoma on helical CT. Methods: The CT images of 9 patients histopathologically proven to have chromophobe renal cell carcinoma and 20 patients with clear cell renal cell carcinoma were reviewed. The tumor sizes, margins, enhancement degrees and patterns, presence or absence of calcification, and tumor spread patterns (including perinephric changes, venous invasion, lymphadenopathy, and distant metastasis) were compared. Results: All the chromophobe renal cell carcinomas showed well-demarcated margins. Thechromophobe renal cell carcinomas showed milder enhancements than the clear cell renal cell carcinomas. The sensitivity and specificity for differentiating the chromophobe renal cell carcinoma from the clear cell renal cell carcinoma were 100 and 88%, respectively, when 101 Hounsfield units was used as the cut-off value in the corticomedullary phase, and 95 and 100% when a less-than-three-time enhancement change was used as a cut-off value in the corticomedullary phase (p<0.05). The chromophobe renal cell carcinomas (67%) tended to show a homogeneous enhancement whereas the clear cell renal cell carcinomas (85%) usually showed a heterogeneous enhancement (p<0.05). Statistical analysis revealed that the frequencies of the tumor spread pattern and calcification in the two subtypes didnot differ significantly (p>0.05). Conclusion: The CT findings of the chromophobe renal cell carcinomascompared to those of the clear cell renal cell carcinomas showed that there were mild enhancements in the corticomedullary phase, homogeneous enhancements, and well-demarcated margins.

• 대한산업공학회지
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• 제41권4호
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• pp.330-337
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• 2015

A bucket-brigade is a way of transporting items where items are passed from one person to the next. The operation of the bucket brigade imitates the cooperative behavior of ants when brood, food or other resources are moved. Koo (2009) presented a bucket brigade-based assembly cell where each worker follows a simple rule: perform assembly operations on a product until the next worker downstream takes it over; then go back to the previous worker upstream to take over a new assembly job. In this way, the flow line is self-balanced without any predetermined job assignment. However, there are some productivity losses related to hand-off and blocking. This paper examines the hand-off and blocking losses and presents a new bucket brigade-based assembly cell where working areas for each assembler is restricted with the help of buffer interfaces. Simulation experiments are used to validate the performance of the new assembly system.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1580-1583
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• 2008

We propose an optical configuration for a vertical alignment (VA) liquid crystal (LC) cell to eliminate the off-axis light leakage in the dark state. The proposed compensation configuration consists of a positive A-film, a positive C-film and a negative C-film. The optical design is performed on a Poincar$\acute{e}$ sphere. This configuration has a better tolerance to the wavelength dispersion, as the polarization trace could self-compensate it. From calculations, we show that the proposed VA LC cell can improve the viewing angle characteristics by compensating for the light leakage in the diagonal direction.

• 정보처리학회논문지C
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• 제9C권3호
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• pp.385-398
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• 2002

제한된 라디오 스펙트럼에서 증가하는 이동 단말기의 수에 따라 서비스를 제공하기 위해서, 무선 시스템은 마이크로/피코 셀룰러 구조와 같이 설계되어야 한다. 이와 같이 다수의 사용자를 수용하기 위하여 셀 크기를 축소하게 되면 핸드오프 이벤트가 증가하게 되며, 안정적인 서비스를 제공하기 위해 효과적 처리해 줄 수 있는 핸드오프 기술이 필수적이라 할 수 있다. Population-Based Bandwidth Reservation(PBR) 구조는 한 셀(Cell)의 이웃에 있는 셀 들에게 셀룰러 트래픽의 양에 따라 대역폭의 양을 동적으로 조절함으로써 핸드오프 호(Hand-off Call)들에게 우선 순위를 제공하는 구조이다. 본 논문에서는 어떤 기간에 발생하는 핸드오프 호에 요구되는 전체 대역폭에 대한 요청 예약 비율을 나타내는 Fractional Parameter, f의 변화에 따라 PBR 구조의 성능을 분석하였다. 파라미터 f의 값은 QoS(Quality of Service) 요구에 따라 결정되어지며, 요구사항을 충족시키기 위하여 변화하는 트래픽 상태에 따라 동적으로 조절된다. f의 최적값은 이동국(Mobile Station)의 속도, 평균 호의 기간, 셀 크기 등에 따라 결정되어진다. 본 논문에서는 이동국의 속도에 따라서 평균 호의 기간과 셀 크기를 가정하였다. 속도에 따라서 약간의 타이가 나지만, 0.4 $\leq$ f $\leq$ 0.6인 경우에서 Blocking Probability, Dropping Probability, Utilization이 최적인 값을 가지게 된다.

• 한국안광학회지
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• 제18권4호
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• pp.533-540
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• 2013

목적: 본 연구에서는 발생 중[태어난 지 5일(P5), 10일(P10)] 마우스 망막의 ON-OFF 방향특이성 신경절세포 수상돌기 상에서 NMDA R1 수용체의 시냅스 패턴을 연구하고자 하였다. 방법: ON-OFF 방향특이성 신경절세포는 Lucifer yellow를 주사하여 형태학적 특징으로 동정하였다. 이극세포로부터의 글루타메이트의 흥분성 유입을 확인하기 위해 membrane traffic motor 단백질 마커인 kinesin을 이용하였다. 결과: 본 연구에서 P5, P10의 ON-OFF 방향특이성 신경절세포를 동정할 수 있었으며, NMDA R1의 면역반응반점은 내망상층에서 강하게 나타났다. ON-OFF 방향특이성 신경절세포의 수상돌기상의 수용체의 분포패턴에서 방향특이성을 예측할 수 있는 어떠한 비대칭성도 발견하지 못하였다. 결론: 이극세포로부터의 글루타메이트성 자극유입은 P5, P10 단계에서 모두 균형적으로 유입되며, 방향특이성은 NMDA R1 수용체의 특이적인 패턴에 있지 않음을 밝혔다.

• Journal of Electrochemical Science and Technology
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• 제13권4호
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• pp.472-478
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• 2022

Solar energy harvesting is practiced by various nations for the purpose of energy security and environment preservation in order to reduce overdependence on oil. Converting solar energy into electrical energy through Photovoltaic (PV) module can take place either in on-grid or off-grid applications. In recent time Lithium battery is exhibiting its presence in on-grid applications but its role in off-grid application is rarely discussed in the literature. The preliminary capacity and Peukert's study indicated that the battery quality is good and can be subjected for life cycle test. The capacity of the battery was 10.82 Ah at 1 A discharge current and the slope of 1.0117 in the Peukert's study indicated the reaction is very fast and independent on rate of discharge. In this study Lithium Iron Phosphate battery (LFP) after initial characterization was subjected to life cycle test which is specific to solar off-grid application as defined in IEC standard. The battery has delivered just 6 endurance units at room temperature before its capacity reached 75% of rated value. The low life of LFP battery in off-grid application is discussed based on State of Charge (SOC) operating window. The battery was operated both in high and low SOC's in off-grid application and both are detrimental to life of lithium battery. High SOC operation resulted in cell-to-cell variation and low SOC operation resulted in lithium plating on negative electrode. It is suggested that to make it more suitable for off-grid applications the battery by default has to be overdesigned by nearly 40% of its rated capacity.