• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.316-326
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• 1999

Purpose: We evaluated the feasibility of extracting pure left ventricular blood pool and myocardial time-activity curves (TACs) and of generating factor images from human dynamic N-13 ammonia PET using factor analysis. The myocardial blood flow (MBF) estimates obtained with factor analysis were compared with those obtained with the user drawn region-of-interest (ROI) method. Materials and Methods: Stress and rest N-13 ammonia cardiac PET imaging was acquired for 23 min in 5 patients with coronary artery disease using GE Advance tomograph. Factor analysis generated physiological TACs and factor images using the normalized TACs from each dixel. Four steps were involved in this algorithm: (a) data preprocessing; (b) principal component analysis; (c) oblique rotation with positivity constraints; (d) factor image computation. Area under curves and MBF estimated using the two compartment N-13 ammonia model were used to validate the accuracy of the factor analysis generated physiological TACs. The MBF estimated by factor analysis was compared to the values estimated by using the ROI method. Results: MBF values obtained by factor analysis were linearly correlated with MBF obtained by the ROI method (slope = 0.84, r = 0.91), Left ventricular blood pool TACs obtained by the two methods agreed well (Area under curve ratio: 1.02 ($0{\sim}1min$), 0.98 ($0{\sim}2min$), 0.86 ($1{\sim}2min$)). Conclusion: The results of this study demonstrates that MBF can be measured accurately and noninvasively with dynamic N-13 ammonia PET imaging and factor analysis. This method is simple and accurate, and can measure MBF without blood sampling, ROI definition or spillover correction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.4
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• pp.347-370
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• 2011

Slurry type shield would be very effective for the tunnelling in a sandy ground, when the slurry pressure would be properly adjusted. Low slurry pressure could cause a tunnel face failure or a ground settlement in front of the tunnel face. Thus, the stability of tunnel face could be maintained by applying an excess slurry pressure that is larger than the active earth pressure. However, the slurry pressure should increase properly because an excessively high slurry pressure could cause the slurry flow out or the passive failure of the frontal ground. It is possible to apply the high slurry pressure without passive failure if a horizontal impermeable layer is located in the ground in front of the tunnel face, but its location, size, and effects are not clearly known yet. In this research, two-dimensional model tests were carried out in order to find out the effect of a horizontal impermeable layer for the slurry shield tunnelling in a saturated sandy ground. In tests slurry pressure was increased until the slurry flowed out of the ground surface or the ground fails. Location and dimension of the impermeable layer were varied. As results, the maximum and the excess slurry pressure in sandy ground were linearly proportional to the cover depth. Larger slurry pressure could be applied to increase the stability of the tunnel face when the impermeable layer was located in the ground above the crown in front of the tunnel face. The most effective length of the impermeable grouting layer was 1.0 ~ 1.5D, and the location was 1.0D above the crown level. The safety factor could be suggested as the ratio of the maximum slurry pressure to the active earth pressure at the tunnel face. It could also be suggested that the slurry pressure in the magnitude of 3.5 ~4.0 times larger than the active earth pressure at the initial tunnel face could be applied if the impermeable layer was constructed at the optimal location.

• Journal of Chest Surgery
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• v.32 no.9
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• pp.773-780
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• 1999

Background: It has been demonstrated that brief periods of calcium depletion and repletion (calcium-free preconditioning, CP) have cardioprotective effects as seen in ischemic preconditioning(IP) which enhances the recovery of post-ischemic contractile dysfunction and reduces the incidence of reperfusion-induced arrhythmia or infarct size after a prolonged ischemia. In the present study, we tested this paradoxical phenomenon in isolated rabbit hearts. Material and Method: Hearts isolated from New Zealand white rabbits(1.5∼2.0 Kg body weight) were perfused with Tyrode solution using the Langendorff technique. After stabilizing the baseline hemodynamics, the hearts were subjected to 45 minutes of global ischemia followed by 120 minutes of reperfusion with IP(IP group, n=7) or without IP (ischemic control group, n=7). IP was induced by a single episode of 5 minutes global ischemia and 10 minutes reperfusion. In the CP group(n=7), the hearts were subjected to perfusion with Tyrode solution with calcium depletion for 5 minutes and repletion for 10 minutes, and 45 minutes of ischemia and 120 minutes of reperfusion. Left ventricular function including developed pressure, dP/dt, heart rate, left ventricular end-diastolic pressure and coronary flow was measured. Infarct size was determined by staining with 1% triphenyltetrazolium chloride and planimetry. Data were analyzed by a one-way analysis of variance and Tukey's post-hoc test. Result: In comparison with the ischemic control group, IP significantly enhanced the recovery of the left ventricular function including the left ventricular developed pressure, contractility, and coronary flow; in contrast, these functional parameters of the CP group tended to be lower than those of the ischemic control group. However, the infarct size was significantly reduced by IP or CP(p<0.05). Conclusion: These results suggest that in isolated Langendorff-perfused rabbit heart model, CP(induced by single episode of 5 minutes calcium depletion and 10 minutes repletion) could not improve the post-ischemic contractile dysfunction(after a 45-minute global ischemia) but it has an infarct size-limiting effect.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.400-425
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• 2018

This study presents the research results and current status of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to simulate the coupled hydro-mechanical behavior of fault, including slip or reactivation, induced by water injection. The first research step of Task B is a benchmark simulation which is designed for the modelling teams to familiarize themselves with the problem and to set up their own codes to reproduce the hydro-mechanical coupling between the fault hydraulic transmissivity and the mechanically-induced displacement. We reproduced the coupled hydro-mechanical process of fault slip using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. A methodology to formulate the hydro-mechanical coupling relations of two different hydraulic aperture models and link the solid element of TOUGH2 and the interface element of FLAC3D was suggested. In addition, we developed a coupling module to update the changes in geometric features (mesh) and hydrological properties of fault caused by water injection at every calculation step for TOUGH-FLAC simulator. Then, the transient responses of the fault, including elastic deformation, reactivation, progressive evolutions of pathway, pressure distribution and water injection rate, to stepwise pressurization were examined during the simulations. The results of the simulations suggest that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing collaboration and interaction with other research teams of DECOLVAEX-2019 Task B and validated using the field data from fault activation experiments in a further study.

• Journal of Intelligence and Information Systems
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• v.27 no.4
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• pp.23-48
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• 2021

The Korean economy has achieved continuous economic growth for the past several decades thanks to the government's export strategy policy. This increase in exports is playing a leading role in driving Korea's economic growth by improving economic efficiency, creating jobs, and promoting technology development. Traditionally, the main factors affecting Korea's exports can be found from two perspectives: economic factors and industrial structural factors. First, economic factors are related to exchange rates and global economic fluctuations. The impact of the exchange rate on Korea's exports depends on the exchange rate level and exchange rate volatility. Global economic fluctuations affect global import demand, which is an absolute factor influencing Korea's exports. Second, industrial structural factors are unique characteristics that occur depending on industries or products, such as slow international division of labor, increased domestic substitution of certain imported goods by China, and changes in overseas production patterns of major export industries. Looking at the most recent studies related to global exchanges, several literatures show the importance of cultural aspects as well as economic and industrial structural factors. Therefore, this study attempted to develop a forecasting model by considering cultural factors along with economic and industrial structural factors in calculating the import volume of each country from Korea. In particular, this study approaches the influence of cultural factors on imports of Korean products from the perspective of PUSH-PULL framework. The PUSH dimension is a perspective that Korea develops and actively promotes its own brand and can be defined as the degree of interest in each country for Korean brands represented by K-POP, K-FOOD, and K-CULTURE. In addition, the PULL dimension is a perspective centered on the cultural and psychological characteristics of the people of each country. This can be defined as how much they are inclined to accept Korean Flow as each country's cultural code represented by the country's governance system, masculinity, risk avoidance, and short-term/long-term orientation. The unique feature of this study is that the proposed final prediction model can be selected based on Design Principles. The design principles we presented are as follows. 1) A model was developed to reflect interest in Korea and cultural characteristics through newly added data sources. 2) It was designed in a practical and convenient way so that the forecast value can be immediately recalled by inputting changes in economic factors, item code and country code. 3) In order to derive theoretically meaningful results, an algorithm was selected that can interpret the relationship between the input and the target variable. This study can suggest meaningful implications from the technical, economic and policy aspects, and is expected to make a meaningful contribution to the export support strategies of small and medium-sized enterprises by using the import forecasting model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.253-266
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• 2014

The ECOM3D is used to study the circulation characteristics and density current from the Sumjin River runoff in the Kwangyang Estuarine System, South Sea, Korea. Annual mean value of $120m^3/s$ was imposed from the Sumjin River. The numerical model results in terms of tidal height, current and salinity field show satisfactory with skill scores over 90%. The current velocity showed the range of 1~2.5 m/s during flood and ebb phases. In particular, very strong flow occur in the narrow Channels of Noryang, Daebang and Changson exceeding over 2.0 m/s. The tidal residual currents in the various locations in the Kwangyang Estuary showed the range of 1~21 cm/s, The density-driven current through the Yeosu and Noryang Channels are about 12 cm/s and 4 cm/s, respectively. The current path through the Yeosu Channel is deflected toward west Bank. Based on budget analysis of the volume flux, the volume flux through the Yeosu Channel and the Noryang Channel were estimated to be 97.4 and $22.1m^3/s$ accounting for the 81.5% and 18.5% of total flux, respectively.

• Journal of Global Scholars of Marketing Science
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• v.18 no.2
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• pp.65-88
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• 2008

Since the implementation of economic reforms in 1978, the Chinese economy grows rapidly at an average annul growth rate of 9% over the post two decades. Franchising has been widely recognized as an important source of entrepreneurial activity. Trust is important in that it facilitates relational exchanges by permits partners to transcend short-run inequities or risks to concentrate on long-term profits or gains. In the relationship between the franchisors and franchisees, trust has been described as an important source of competitive advantage. However, little research has been done on the factors affecting trust in Chinese franchisor-franchisee relationships. The purpose of this study is to investigate what factors affect the trust in the franchise system in China, and to provide guidelines and insights to franchisors which enter Chinese market. In this study, according to Morgan and Hunt (1994), trust is defined as the extending when one party has confidence in an exchange partner's reliability and integrity. We offered a conceptual model of the empirical study. The model shows that the factors affecting the trust include franchisor's supports, communication, satisfaction with previous outcome and conflict. We also suggested the franchisor's supports and communication like to enhance the franchisee's satisfaction with previous outcome, and the franchisor's supports, communication and he franchisee's satisfaction with previous outcome tend to decrease conflict. Before the formal study, a pretest involving exploratory interviews with owners from three franchisees was conducted to make sure the questionnaire was relevant and clear to the respondents. The data were collected using trained interviewers to carry out personal interviews with the aid of an unidentified, muti-page, structured questionnaire. The respondents comprised of owners, managers, and owner managers of franchisee-owned food service franchises located in Beijing, China. Even though a total of 256 potential franchises were initially contacted, the finally usable sample consisted of 125 respondents. As expected, the sampling method was successful in soliciting respondents with waried personal and firm characteristics. Self-administrated questionnaires were used for all measures. And established scales were used to measure the latent constructs in this study. The measures tapped the franchisees' perceptions of the relationship with the referent franchisor. Five-point Likert-type scales ranging from "strongly disagree" (=1) to "strongly agree" (=7) were used throughout the constructs (trust, eight items; support, five items; communication, four items; satisfaction, six items; conflict, three items). The reliability measurements traditionally employed, such as the Cronbach's alpha, were used. All the reliabilities were greater than.80. The proposed measurement model was estimated using SPSS 12.0 and AMOS 5.0 analysis package. We conducted A series of exploratory factor analyses and confirmatory factor analyses to assess the convergent validity, discriminant validity, and reliability. The results indicate reasonable overall fits between the model and the observed data. The overall fit of measurement model were $X^2$= 159.699, p=0.004, d.f. = 116, GFI =.879, NFI =.898, CFI =.969, IFI =.970, TLI =.959, RMR =.058. The results demonstrated that the data reasonably fitted the model. We also examined construct reliability and reliability and average variance extracted (AVE). The construct reliability of each construct was greater than.80 and the AVE of each construct was greater than.50. According to the analysis of Structure Equation Modeling (SEM), the results of path model indicated an adequate fit of the model: $X^2$= 142.126, p = 0.044, d.f. = 115, GFI =.892, NFI =.909, CFI =.981, IFI =.981, TLI =.974, RMR =.057. As hypothesized, the results showed that it is strategically important to establish trust in a franchise system, and the franchisor's supports, communication and satisfaction with previous outcome tend to reinforce franchisee's trust. The results also showed trust seems to decrease as the experience of conflict episodes increases. And we also noticed that franchisor's supports and communication tend to enhance the franchisee's satisfaction with previous outcome, and communication tend to decrease conflict. If the trust between the franchisor and franchisee can be established in a franchise system, franchising offers many benefits and reduces many costs. To manage a mutual trust of relationship with their franchisees, franchisor's should provide support effectively to their franchisees. Effective assistant services have direct effect on franchisees' satisfaction with previous outcome and trust in franchisor. Especially, franchise sales process, orientation, and training in the start-up period are key elements for success of the franchise system. Franchisor's support is an accumulated separate satisfaction evaluation with different kind of service provided by the franchisor. And providing support definitely can improve the trustworthy image of the franchisor. In the franchise system, conflicts of interests and exertions of different power sources are very common. The experience of conflict episodes seems to negatively relate to trust. Therefore, it is important to reduce the negative side of the relationship conflicts. Communication actually plays a broader role in reducing conflict and establish mutual trust in franchisor-franchisee relationship. And effective communication between franchisors and franchisees can improve franchisees' satisfaction toward the franchise system. As the diversification of Chinese markets, both franchisors and franchisees must keep the relevant, timely, and reliable communication. And it is very important to improve the quality of communication. Satisfaction with precious outcomes seems to positively relate to trust. Franchisors and franchisees that are highly satisfied with the previous outcomes that flow from their relationship will perceive their partner as advancing their goal achievement. Therefore, it is necessary for both franchisor and their franchisees to make the welfare of partner with effort. Little literature has focused on what factors affect the trust between franchisors and their franchisees in China. This study developed the hypotheses regarding the factors affecting trust in the transaction relationship. The results of data analysis supported the hypotheses strongly. There are certain limitations in this study. First, we may point out that some other factors missed in this study could be significantly important. Second, the context of this study, food service industry, limits its potential generalizability for all franchise systems. More studies in different categories of franchise system are needed to broaden its generalizability. Third, the model was tested empirically in a sample in Beijing, more empirical tests of the proposed model in other Chinese areas are needed. Finally, the analysis in this study was solely based on the perception of franchisees and the opinions of franchisors were not included.

• Imaging Science in Dentistry
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• v.33 no.3
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• pp.143-149
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• 2003

Purpose: To investigate the radiosensitivity of the normal human oral keratinocytes (NHOK), and the effect of irradiation on cell cycle and protein expression. Materials and Methods: To evaluate the radiosensitivity of NHOK, the number of colonies and cells were counted after irradiation and the SF2 (survival fraction at 2Gy) value, and the cell survival curve fitted on a linear-quadratic model were obtained. LDH analysis was carried out to evaluate the necrosis of NHOK at 1, 2, 3, and 4 days after 2, 10, and 20 Gy irradiation. Cell cycle arrest and the induction of apoptosis were analyzed using flow cytometry at 1, 2, 3, and 4 days after 2, 10, and 200y irradiation. Finally, proteins related cell cycle arrest and apoptosis were analysed by Western blot. Results: The number of survived cell was significantly decreased in a dose-dependent manner. The cell survival curve showed SF2, α, and β values to be 0.568, 0.209, and 0.020 respectively. At 200y irradiated cells showed higher optical density than the control group. After irradiation, apoptosis was not observed but G2 arrest was observed in the NHOK cells. 1 day after 10 Gy irradiation, the expression of p53 remained unchanged, the p2l/sup WAF1/Cipl/ increased and the mdm2 decreased. The expression of bax, bcl-2, cyclin B1, and cyclin D remained unchanged. Conclusion: These results indicate that NHOK responds to irradiation by G2 arrest, which is possibly mediated by the expression of p21/sup WAFl/Cipl/, and that cell necrosis occurs by high dose irradiation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6447-6454
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• 2013

Seawater intake systems have significant problems due to seawater pollution, suspended solids, unstable intake and maintenance etc. An underground type seawater intake system was newly developed to overcome the existing weaknesses and was facilitated in Gyukpo port. In this study, to check the performance of the new system, the samples for water quality and the 3-D numerical modeling test were conducted. The five times test included the COD, total nitrogen, total phosphorus, pH, and suspended solid for the intake system. The analyses show that the COD, total nitrogen, total phosphorus, PH showedminor changes before and after. On the other hand, the change in suspended solids was significant and water was purified below 5 mg/l, first level fisheries water, after. The numerical model adopted the RNG $k-{\epsilon}$ algorithm and the CFX model based on the finite volume method. The porosity algorithm was used to reproduce filtered-sand, outer diameter, and thickness. The numerical results showed that the double pipe is advantageous in that it provides a uniform pressure between the inner and outer pipe for the flow to be stable. In addition, the use of multiple intake pipes did not interfere with the discharge reduction of 0.98 at the both intake pipes compared with the central intake pipe.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.6039-6046
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• 2015

Aims: To investigate effect of metallic nanoparticles, silver (AgNPs) and gold nanoparticles (AuNPs) as antitumor treatment in vitro against human breast cancer cells (MCF-7) and their associated mechanisms. This could provide new class of engineered nanoparticles with desired physicochemical properties and may present newer approaches for therapeutic modalities to breast cancer in women. Materials and Methods: A human breast cancer cell line (MCF-7) was used as a model of cells. Metallic nanoparticles were characterized using UV-visible spectra and transmission electron microscopy (TEM). Cytotoxic effects of metallic nanoparticles on MCF-7 cells were followed by colorimetric SRB cell viability assays, microscopy, and cellular uptake. Nature of cell death was further investigated by DNA analysis and flow cytometry. Results: Treatment of MCF-7 with different concentrations of 5-10nm diameter of AgNPs inhibited cell viability in a dose-dependent manner, with IC50 value of $6.28{\mu}M$, whereas treatment of MCF-7 with different concentrations of 13-15nm diameter of AuNPs inhibited cell viability in a dose-dependent manner, with IC50 value of $14.48{\mu}M$. Treatment of cells with a IC50 concentration of AgNPs generated progressive accumulation of cells in the S phase of the cell cycle and prevented entry into the M phase. The treatment of cells with IC50 concentrations of AuNPs similarly generated progressive accumulation of cells in sub-G1 and S phase, and inhibited the entrance of cells into the M phase of the cell cycle. DNA fragmentation, as demonstrated by electrophoresis, indicated induction of apoptosis. Conclusions: Our engineered silver nanoparticles effectively inhibit the proliferation of human breast carcinoma cell line MCF-7 in vitro at high concentration ($1000{\mu}M$) through apoptotic mechanisms, and may be a beneficial agent against human carcinoma but further detailed study is still needed.