• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.119-120
• /
• 2004

Urban groundwater has a unique hydrologic system because of the complex surface and subsurface infrastructures such as deep foundation of many high buildings, subway systems, and sewers and public water supply systems. It generally has been considered that increased surface impermeability reduces the amount of groundwater recharge. On the other hand, leaks from sewers and public water supply systems may generate the large amounts of recharges. All of these urban facilities also may change the groundwater quality by the recharge of a myriad of contaminants. This study was performed to determine the factors controlling the recharge of deep groundwater in an urban area, based on the hydrogeochemical characteristics. The term ‘contamination’ in this study means any kind of inflow of shallow groundwater regardless of clean or contaminated. For this study, urban groundwater samples were collected from a total of 310 preexisting wells with the depth over 100 m. Random sampling method was used to select the wells for this study. Major cations together with Si, Al, Fe, Pb, Hg and Mn were analyzed by ICP-AES, and Cl, N $O_3$, N $H_4$, F, Br, S $O_4$and P $O_4$ were analyzed by IC. There are two groups of groundwater, based on hydrochemical characteristics. The first group is distributed broadly from Ca-HC $O_3$ type to Ca-C1+N $O_3$ type; the other group is the Na+K-HC $O_3$ type. The latter group is considered to represent the baseline quality of deep groundwater in the study area. Using the major ions data for the Na+K-HC $O_3$ type water, we evaluated the extent of groundwater contamination, assuming that if subtract the baseline composition from acquired data for a specific water, the remaining concentrations may indicate the degree of contamination. The remainder of each solute for each sample was simply averaged. The results showed that both Ca and HC $O_3$ represent the typical solutes which are quite enriched in urban groundwater. In particular, the P$CO_2$ values calculated using PHREEQC (version 2.8) showed a correlation with the concentrations of maior inorganic components (Na, Mg, Ca, N $O_3$, S $O_4$, etc.). The p$CO_2$ values for the first group waters widely ranged between about 10$^{-3.0}$ atm to 10$^{-1.0}$ atm and differed from those of the background water samples belonging to the Na+K-HC $O_3$ type (<10$^{-3.5}$ atm). Considering that the p$CO_2$ of soil water (near 10$^{-1.5}$ atm), this indicates that inflow of shallow water is very significant in deep groundwaters in the study area. Furthermore, the P$CO_2$ values can be used as an effective parameter to estimate the relative recharge of shallow water and thus the contamination susceptibility. The results of our present study suggest that down to considerable depth, urban groundwater in crystalline aquifer may be considerably affected by the recharge of shallow water (and pollutants) from an adjacent area. We also suggest that for such evaluation, careful examination of systematically collected hydrochemical data is requisite as an effective tool, in addition to hydrologic and hydrogeologic interpretation.ion.ion.

• Journal of Chest Surgery
• /
• v.36 no.12
• /
• pp.904-910
• /
• 2003

Thoracoscopic bullectomy (VATS-B) is now the preferred treatment for spontaneous pneumothorax despite of higher recurrence rate than open thoracotomy. Several methods have been used to prevent this problem. The effectiveness of staple line reinforcement (SLR) in VATA-B using endostaplers was assessed by clinical and experimental study. Meterial and Method: In experimental study, canine lungs were harvested immediately (group I N=5) and 48 hours (group II N=5) after stapling. The pressures at which initial air leaks occurred were measured. In clinical study from February 1997 to March 1999, 106 procedures in 104 patients undergoing VATS-B for spontaneous pneumothorax were classified into two groups according to the presence of SLR and were compared. Result: The average pressure of the initial air leakage was significantly higher in SLR than that of staples alone (18$\pm$1.6 vs 48$\pm$3 mm Hg in group I; 23.8$\pm$1.9 vs 54$\pm$4.6 mm Hg in group II, p<0.001). In the clinical data, there were significant differences seen in the duration of drainage, the total length of endostaplers used, and the duration of the postoperative hospital stay between patients with staple alone and patients with SLR (4.4$\pm$1.4 vs 3.1$\pm$1.1 days in duration of drainage, 92.3$\pm$28.1 vs 71.1$\pm$30.6 mm in total length of endostaplers used, 5.9$\pm$1.9 vs 4.6$\pm$1.7 days in postoperative hospital stays, p<0.001). Conclusion: SLR was effective for preventing prolonged air leakage and responsible for shorter hospital stays after VATS-B for the treatment of spontaneous pneumothorax.

• Journal of Chest Surgery
• /
• v.41 no.6
• /
• pp.729-735
• /
• 2008

Background: This study was performed to evaluate the safety and efficacy of performing additional tetracycline pleurodesis during the thoracoscopic treatment of primary spontaneous pneumothorax. Material and Method: Between March 2004 and December 2007, 91 cases of primary spontaneous pneumothorax were treated by video-assisted thoracoscopic surgery. The thoracoscopic procedures included resection of the blebs and mechanical pleurodesis by scrubbing the parietal pleura. For 27 cases (Tetracycline group, group I), 20 mg/kg tetracycline was instilled into the pleural space through a trocar before closing the chest. The control group (group II) consisted of 64 cases of primary spontaneous pneumothorax for which the same thoracoscopic procedures alone were performed during the same study period. Result: There was no significant difference between the two groups in terms of the demographic data, the operative findings and the operation time. The percentage of cases that needed intravenous analgesics and the duration of intravenous analgesics were comparable in both groups. There was no significant difference in the duration of air leaks and complications between the two groups. The patients treated with tetracycline pleurodesis had a longer period of postoperative chest drainage (4.2 days vs 3.5 days, respectively, p=0.03) and hospitalization (5.0 days vs 4.0 days, respectively, p=0.006). During the follow up period, the ipsilateral recurrence rate was much lower for the patients who were treated with tetracycline pleurodesis (0% vs 10.9%, respectively, p=0.099), and freedom from recurrence tended to be more favorable for group I (p=0.077), although this was not statistically significant. Conclusion: Additional tetracycline pleurodesis during thoracoscopic treatment for primary spontaneous pneumothorax caused prolongation of chest drainage and a prolonged hospital stay. However, further investigations are needed because tetracycline pleurodesis can be performed safely without serious complications and it showed a distinct tendency to reduce the rate of recurrence.

• Journal of the Society of Disaster Information
• /
• v.9 no.4
• /
• pp.449-461
• /
• 2013

As the hydrofluoric acid leak in Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak in Ulsan, Gyeongsangnam-do demonstrated, chemical related accidents are mostly caused by large amounts of volatile toxic substances leaking due to the damages of storage tank or pipe lines of transporter. Safety assessment is the most important concern because such toxic material accidents cause human and material damages to the environment and atmosphere of the surrounding area. Therefore, in this study, a hydrofluoric acid leaked from a storage tank was selected as the study example to simulate the leaked substance diffusing into the atmosphere and result analysis was performed through the numerical Analysis and diffusion simulation of ALOHA(Areal Location of Hazardous Atmospheres). the results of a qualitative evaluation of HAZOP (Hazard Operability)was looked at to find that the flange leak, operation delay due to leakage of the valve and the hose, and toxic gas leak were danger factors. Possibility of fire from temperature, pressure and corrosion, nitrogen supply overpressure and toxic leak from internal corrosion of tank or pipe joints were also found to be high. ALOHA resulting effects were a little different depending on the input data of Dense Gas Model, however, the wind direction and speed, rather than atmospheric stability, played bigger role. Higher wind speed affected the diffusion of contaminant. In term of the diffusion concentration, both liquid and gas leaks resulted in almost the same $LC_{50}$ and ALOHA AEGL-3(Acute Exposure Guidline Level) values. Each scenarios showed almost identical results in ALOHA model. Therefore, a buffer distance of toxic gas can be determined by comparing the numerical analysis and the diffusion concentration to the IDLH(Immediately Dangerous to Life and Health). Such study will help perform the risk assessment of toxic leak more efficiently and be utilized in establishing community emergency response system properly.

• Journal of Intelligence and Information Systems
• /
• v.20 no.4
• /
• pp.59-87
• /
• 2014

In MIS field, the researches on payment services are focused on adoption factors of payment service using behavior theories such as TRA(Theory of Reasoned Action), TAM(Technology Acceptance Model), and TPB (Theory of Planned Behavior). The previous researches presented various adoption factors according to types of payment service, nations, culture and so on even though adoption factors of identical payment service were presented differently by researchers. The payment service industry relatively has strong path dependency to the existing payment methods so that the research results on the identical payment service are different due to payment culture of nation. This paper aims to suggest a successful adoption factor of noble payment service regardless of nation's culture and characteristics of payment and prove it. In previous researches, common adoption factors of payment service are convenience, ease of use, security, convenience, speed etc. But real cases prove the fact that adoption factors that the previous researches present are not always critical to success to penetrate a market. For example, PayByPhone, NFC based parking payment service, successfully has penetrated to early market and grown. In contrast, Google Wallet service failed to be adopted to users despite NFC based payment method which provides convenience, security, ease of use. As shown in upper case, there remains an unexplained aspect. Therefore, the present research question emerged from the question: "What is the more essential and fundamental factor that should takes precedence over factors such as provides convenience, security, ease of use for successful penetration to market". With these cases, this paper analyzes four cases predicted on the following hypothesis and demonstrates it. "To successfully penetrate a market and sustainably grow, new payment service should find non-customer of the existing payment service and provide noble payment method so that they can use payment method". We give plausible explanations for the hypothesis using multiple case studies. Diners club, Danal, PayPal, Square were selected as a typical and successful cases in each category of payment service. The discussion on cases is primarily non-customer analysis that noble payment service targets on to find the most crucial factor in the early market, we does not attempt to consider factors for business growth. We clarified three-tier non-customer of the payment method that new payment service targets on and elaborated how new payment service satisfy them. In case of credit card, this payment service target first tier of non-customer who can't pay for because they don't have any cash temporarily but they have regular income. So credit card provides an opportunity which they can do economic activities by delaying the date of payment. In a result of wireless phone payment's case study, this service targets on second of non-customer who can't use online payment because they concern about security or have to take a complex process and learn how to use online payment method. Therefore, wireless phone payment provides very convenient payment method. Especially, it made group of young pay for a little money without a credit card. Case study result of PayPal, online payment service, shows that it targets on second tier of non-customer who reject to use online payment service because of concern about sensitive information leaks such as passwords and credit card details. Accordingly, PayPal service allows users to pay online without a provision of sensitive information. Final Square case result, Mobile POS -based payment service, also shows that it targets on second tier of non-customer who can't individually transact offline because of cash's shortness. Hence, Square provides dongle which function as POS by putting dongle in earphone terminal. As a result, four cases made non-customer their customer so that they could penetrate early market and had been extended their market share. Consequently, all cases supported the hypothesis and it is highly probable according to 'analytic generation' that case study methodology suggests. We present for judging the quality of research designs the following. Construct validity, internal validity, external validity, reliability are common to all social science methods, these have been summarized in numerous textbooks(Yin, 2014). In case study methodology, these also have served as a framework for assessing a large group of case studies (Gibbert, Ruigrok & Wicki, 2008). Construct validity is to identify correct operational measures for the concepts being studied. To satisfy construct validity, we use multiple sources of evidence such as the academic journals, magazine and articles etc. Internal validity is to seek to establish a causal relationship, whereby certain conditions are believed to lead to other conditions, as distinguished from spurious relationships. To satisfy internal validity, we do explanation building through four cases analysis. External validity is to define the domain to which a study's findings can be generalized. To satisfy this, replication logic in multiple case studies is used. Reliability is to demonstrate that the operations of a study -such as the data collection procedures- can be repeated, with the same results. To satisfy this, we use case study protocol. In Korea, the competition among stakeholders over mobile payment industry is intensifying. Not only main three Telecom Companies but also Smartphone companies and service provider like KakaoTalk announced that they would enter into mobile payment industry. Mobile payment industry is getting competitive. But it doesn't still have momentum effect notwithstanding positive presumptions that will grow very fast. Mobile payment services are categorized into various technology based payment service such as IC mobile card and Application payment service of cloud based, NFC, sound wave, BLE(Bluetooth Low Energy), Biometric recognition technology etc. Especially, mobile payment service is discontinuous innovations that users should change their behavior and noble infrastructure should be installed. These require users to learn how to use it and cause infra-installation cost to shopkeepers. Additionally, payment industry has the strong path dependency. In spite of these obstacles, mobile payment service which should provide dramatically improved value as a products and service of discontinuous innovations is focusing on convenience and security, convenience and so on. We suggest the following to success mobile payment service. First, non-customers of the existing payment service need to be identified. Second, needs of them should be taken. Then, noble payment service provides non-customer who can't pay by the previous payment method to payment method. In conclusion, mobile payment service can create new market and will result in extension of payment market.