• International Journal of Automotive Technology
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• v.6 no.4
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• pp.323-332
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• 2005

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.555-561
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• 2005

This experimental study was executed to obtain basic data for actual engine operation using radical induced ignition method (RI) which can achieve emission reduction and high efficiency due to the rapid bulk combustion. In this study, a direct injection diesel engine was converted into SI type engine with a sparkplug. The modified SI type engine can be divided into two classes. One is the SI engine with a sparkplug only at the cylinder head, and the other is the SI engine with the sparkplug which is enveloped in a sub-chamber. Also, a basic experimental was conducted in order to investigate combustion mechanism of radical induced injection before the experiment execution for actual engine using the modified SI engine. The bulk combustion phenomenon of radical induced ignition method was analyzed from the basic experiment by using a constant volume chamber. Volume value of sub-chamber used in this experiment is approximately $0.2\%$ of one of the main combustion chamber. In this paper, combustion characteristics using radical induced injection method was compared with that of using spark ignition method according to change in the engine speed and equivalence ratio. As a result, in the case of the radical induced injection engine, the combustion duration and cycle variation were respectively reduced ranged from $\Phi$(equivalence ratio)=0.8 (lean mixture ratio) to $\Phi$=1.0 (stoichiometric ratio).

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7831-7834
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• 2014

Objective: To explore the influence of different ways of blood transfusion on the expression levels of interleukins (IL) and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) inperi-operative patients with esophageal cancer. Materials and Methods: A total of 80 patients with esophageal cancer who underwent radical operations were selected as study patients and randomly divided into an observation group (treated with autologous blood transfusion) and control group (with homologous blood transfusion). Changes of intra-operative indexes and peri-operative blood indexes, from hemoglobin (Hb) and hematocrit value (Hct), to levels of inflammatory factors like interleukins-6 (IL-6), IL-8, IL-10 and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) were compared. Results: Operations for patients in both groups were successfully conducted, and no significant differences in mean surgical duration and intra-operative hemorrhage volume, fluid infusion volume and blood transfusion volume were detected (p>0.05). Compared with values before surgery, Hb and Hct levels decreased significantly while white blood cell count (WBC) increased 1, 5 and 7 d after operation (p<0.05, p<0.01). In addition, WBC was apparently higher in observation group than in control group 5 and 7 d after operation (p<0.01). Compared with before surgery, in the observation group, levels of IL-6, IL-8 and IL-10 had no significant differences after operation (P>0.05), but TNF-${\alpha}$ level increased y (p<0.01), whereas in control group, IL-6 level had no significant difference (p>0.05), IL-8 level decreased obviously (p<0.05), IL-10 level increased markedly first and then decreased gradually as time passed but its level remained elevated (p<0.01), and TNF-${\alpha}$ level increased first and then decreased, and there was no significant difference 7 d after operation (p>0.05). Conclusions: Decreased IL-8 and increased IL-10 levels are two important reasons for immunosuppression after homologous blood transfusion, whereas autologous blood transfusion can alleviate this while increasing the TNF-${\alpha}$ level, which also has potential to improve anti-tumor immunity in the human body.

• Archives of Plastic Surgery
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• v.39 no.5
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• pp.509-513
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• 2012

Background The extended latissimus dorsi flap is important for breast reconstruction. Unfortunately, donor site seroma is the most common complication of extended latissimus dorsi flap for breast reconstruction. Although using fibrin sealant in the donor site reduces the rate of seroma formation, donor site seroma remains a troublesome complication. The purpose of this study was to analyze the effectiveness of the combination of quilting sutures and fibrin sealant in the latissimus dorsi donor site for the prevention of seroma. Methods Forty-six patients who underwent breast reconstruction with extended latissimus flap were enrolled in the study. The patients received either fibrin sealant (group 1, n=25) or a combination of fibrin sealant and quilting sutures (group 2, n=21) in the extended latissimus dorsi donor site. Outcome measures were obtained from the incidence, volume of postoperative seroma, total drainage amount, indwelling period of drainage, and duration of hospital stay. Results The incidence of seroma was 76% in group 1 and 42.9% in group 2 (P=0.022). We also found significant reductions in seroma volume (P=0.043), total drainage amount (P=0.002), indwelling period of drainage (P=0.01), and frequency of aspiration (P=0.043). The quilting sutures did not affect the rate of drainage, tube reinsertion, or hospital stay. Conclusions The use of quilting sutures combined with fibrin sealant on the latissimus dorsi flap donor site is helpful for reducing the overall seroma volume, frequency of aspiration, and total drainage amount.

• Journal of Korean Neurosurgical Society
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• v.39 no.2
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• pp.102-108
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• 2006

Objective : The management of diffuse astrocytomas is one of the most controversial areas in clinical neurooncology. There are numerous reviews and editorials outlining the difficulties in the management of these lesions. In this study, we assess the role of Gamma Knife radiosurgery[GKS] for diffuse astrocytomas. Methods : Twenty-three patients with a diffuse astrocytoma were treated with GKS as a primary or adjuvant method from February 1995 to October 2003. The mean marginal dose was $13.6\;[8.5{\sim}17.5]Gy$ and the mean maximal dose was $27.3\;[17.0{\sim}35.0]Gy$. Local control and the pattern of radiologic response were evaluated. The probable factors affecting local control, such as tumor volume, margin dose, previous history of craniotomy or stereotactic biopsy, and the presence or absence of previous radiotherapy were statistically analyzed. The average duration of follow-up was 39.7 [$11.3{\sim}101.5$] months after GKS. Results : Of the 23 lesions treated, 16 lesions [69.6%] were controlled during the follow-up period. The mean progression-free interval was 57.4 months and the 5-year progression-free rate was 68%. Only tumor volume was found to be a statistically significant factor for local control. Smaller tumors were better controlled by GKS; it was significantly effective in tumors with less than $10cm^3$ volume. Conclusion : GKS could be a valuable therapeutic modality both as a primary treatment and as a postoperative adjuvant therapy in some selected cases.

• Journal of Information Technology Services
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• v.19 no.2
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• pp.11-21
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• 2020

This study explores the effect of time-deals, i.e., online promotions with time limit. Recently many online/mobile shopping sites in China utilize so called hot deal marketing technique for a short duration at a specific time. The purpose of "time-deals" is to attract online shoppers with deep discounted price and induce consumers to purchase items. This paper examines the effect of time-deals on sales volume, firstly by comparing the sales volume of time-deal days with that of no time-deal days and secondly by comparing the sales volume of days before and after two types of time deals, usual time-deals and special time-deals, Although some prior research studied the role of time-deals in promoting consumers' purchase behavior, most used the experimental approach by building mock-up shopping sites and asking participants purchase intention. However, purchase intention does not always result in purchase behavior. This study extracted actual purchase data for four items on time-deals from an online shopping site in China. A comparison of sales volumes on time-deal days with no time-deal days has shown the significant difference in the sales volumes. This finding confirms the positive effect of time-deals on purchase behavior. This study has also found that special time-deals soak up near-future demands in advance and lower the sales after the special time-deal event, although there is no significant difference in sales before and after usual time-deals.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1027-1036
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• 2020

In this study, a cloud-based processing method using Agisoft Metashape, a commercial software, and Amazon web service, a cloud computing service, is introduced and evaluated to quickly generate high-precision 3D realistic data from large volume UAV images acquired in disaster sites. Compared with on-premises method using a local computer and cloud services provided by Agisoft and Pix4D, the processes of aerial triangulation, 3D point cloud and DSM generation, mesh and texture generation, ortho-mosaic image production recorded similar time duration. The cloud method required uploading and downloading time for large volume data, but it showed a clear advantage that in situ processing was practically possible. In both the on-premises and cloud methods, there is a difference in processing time depending on the performance of the CPU and GPU, but notso much asin a performance benchmark. However, it wasfound that a laptop computer equipped with a low-performance GPU takes too much time to apply to in situ processing.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.116-122
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• 2012

The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fuel. In a constant volume chamber, the injected spray was visualized by the spray visualization system, which consisted of the high-speed camera, the metal-halide lamp, the injector control device, and the image analysis system with the image processing program. It was revealed that the injection quantity was mainly affected by the difference between the injection pressure and the ambient pressure. For low injection pressure conditions, the injection quantity was decreased by the increase of the ambient pressure, while it nearly maintained regardless of the ambient pressure at high injection pressure. According to the increase of the ambient pressure in the constant volume chamber, the spray development became slow, consequently, the spray tip penetration decreased, and the spray area increased. In additions, the circular cone area decreased, and the vortex area increased.

• The Journal of Fisheries Business Administration
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• v.31 no.2
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• pp.133-153
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• 2000

During the last several decades, Korea has been regarded as one of the fastest growing economies in the world. However, the small size of national land has not met the vigorous demand for land necessary to develop economic infra-structures such as large-scale harbors airports and highways. In order to satisfy the growing demand for land, the Korean government and industry have implemented the national land development programs to reclaim land from the sea fur the several decades. It is certain that these land development programs have resulted in a lot of property disputes between fishermen and public project administrators. This paper is to develop a quantitative model to estimate compensation for damages or restriction of charted fisheries resulting from large-scale public projects. In this paper, the compensation model is derived by using cost-volume-profit analysis framework because the compensation for charted fisheries basically depends on the factors such as the costs, production volume, profit of charted fisheries damaged or restricted by public projects. The model shows that the compensation for damages or restriction of charted fisheries is determined by the average annual profit, damage duration period, and the degree of fishery damages. In addition, the degree of fishery damages measured by the ratio of lost profit to annual average profit turns out to be determined by the following factors: annul profit, unit variable cost, decrease in production volume, the rate of increase in variable cost, and a change in fixed cost. Furthermore, this parer discusses the nam issues related to practices and regulation of the compensation for fishery damages in the current Fishery Act of Korea and suggests some appraisal methods which will be able to lead to theoretically correct and fair compensation for fisheries damages resulting from large-scale public projects.

• International Journal of Computer Science & Network Security
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• v.23 no.2
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• pp.183-192
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• 2023

Radiofrequency ablation (RFA) is an alternative treatment for liver cancer to the surgical intervention preferred by surgeons. However, the main challenge remains the use of RF for the ablation of large tumours (i.e., tumours with a diameter of >3 cm). For large tumours, RFA takes a large duration in the ablation process compared with surgery, which increases patient pain. Therefore, RFA for large tumours is not preferred by surgeons. The currently materials used in RF electrodes, such as the nickeltitanium alloy (nitinol), are characterized by low thermal and electrical conductivities. On the other hand, the use of materials that have high thermal and electrical conductivities, such as titanium aluminide alloy (gamma titanium), produces more thermal energy for tumours. In this paper, we developed a cool-tip RF electrode model that uses nickel-titanium alloy and replaced it with titanium aluminide alloy by using the finite element model (FEM). The aim of this paper is to study the effect of the thermal and electrical conductivities of gamma titanium on the ablation volume. Results showed that the proposed design of the electrode increased the ablation rate by 1 cm³ /minute and 6.3 cm³/10 minutes, with a decrease in the required time ablation. Finally, the proposed model reduces the ablation time and damages healthy tissue while increasing the ablation volume from 22.5% cm³ to 62.5% cm³ in ten minutes compared to recent studies.