• The Journal of the Acoustical Society of Korea
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• v.28 no.7
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• pp.646-652
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• 2009

In this paper, welding pitch optimization technique of vehicle subframe is presented considering the fatigue life of spot welding nuggets. Fatigue life of spot welding nuggets is estimated by using the frequency-domain fatigue analysis technique. The input data, which are used in the fatigue analysis, are obtained by performing the dynamic analysis of vehicle model passing through the Belgian road profile and also the modal frequency response analysis of finite element model of vehicle subframe. According to the fatigue life result obtained from the frequency-domain fatigue analysis, the design points to optimize the weld pitch distance are determined. For obtaining the welding pitch combination to maximize the fatigue life of the spot welding nuggets, 4-factor, 3-level orthogonal array experimental design is used. This study shows that the optimized subframe improves the fatigue life of welding nugget with minimum fatigue life about 65.8 % as compared with the baseline design.

• Wind and Structures
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• v.38 no.4
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• pp.261-275
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• 2024

Before performing an experimental study on the downburst-generated wave, it is necessary to examine the scale effects and corresponding corrections or compensations. Analysis of similarity is conducted to conclude the non-dimensional force ratios that account for the dynamic similarity in the interaction of downburst with wave between the prototype and the scale model, along with the corresponding scale factors. The fractional volume of fluid (VOF) method in association with the impinging jet model is employed to explore the characteristics of the downburst-generated wave numerically, and the validity of the proposed scaling method is verified. The study shows that the location of the maximum radial wind velocity in a downburst-wave field is a little higher than that identified in a downburst over the land, which might be attributed to the presence of the wave which changes the roughness of the underlying surface of the downburst. The impinging airflow would generate a concavity in the free surface of the water around the stagnation point of the downburst, with a diameter of about two times the jet diameter (D_jet). The maximum wave height appears at the location of 1.5D_jet from the stagnation point. Reynolds number has an insignificant influence on the scale effects, in accordance with the numerical investigation of the 30 scale models with the Reynolds number varying from 3.85 × 10⁴ to 7.30 × 10⁹. The ratio of the inertial force of air to the gravitational force of water, which is denoted by G, is found to be the most significant factor that would affect the interaction of downburst with wave. For the correction or compensation of the scale effects, fitting curves for the measures of the downburst-wave field (e.g., wind profile, significant wave height), along with the corresponding equations, are presented as a function of the parameter G.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.5
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• pp.1-16
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• 2022

Although start-up is a key national strategy to increase national competitiveness and create employment, the survival rate of start-ups has not improved significantly. This is an important reason for the inability to provide timely and appropriate support to startups, which are in the early stages of start-up, due to the unique limitations of existing start-up support institutions and investors. The relatively recent accelerator is attracting attention as a subject of solving the above problems through professional incubation and investment. However, there are only a few empirical studies on investment determinants that affect the survival and success of accelerators, and there is a lack of theoretical evidence. Accordingly, in previous studies, 12 investment determinants were derived from a static, strategic, and dynamic perspective as accelerator investment determinants based on a business model innovation framework. This study subdivided the accelerator investment determinants derived through previous studies into 21 and analyzed the importance and priority of each factor using AHP (Analytic Hierarchy Process) analysis technique for domestic accelerator investment experts. As a result of the analysis, the top factors of importance of accelerator investment determinants were in the order of 'human resources', 'customer and market', 'intellectual resources', and 'entrepreneur's ability to realize opportunities'. It can be seen that the accelerator considers the core competencies of startups to implement solutions as the most important factor when making startup investment decisions. It was also confirmed that accelerators are strategic to create a clear value proposition and differentiated market position based on the core competitiveness of startups, and that the core value delivery method prefers a market-oriented business model and recognizes entrepreneurs's innovation capability is an important factor to realize a business model with limited resources in a rapidly changing market. This study is of academic significance in that it analyzes the importance and priority of accelerator investment determinants through demonstration as a follow-up study on accelerator investment determinants derived based on business model innovation theory that reflects the nature, goals, and major activities of accelerator investment. In addition, it is of practical value as it contributes to revitalizing the domestic startup investment ecosystem by providing accelerators with theoretical grounds for investment decisions and specific information on detailed investment determinants.

• Journal of Korean Academy of Nursing
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• v.30 no.5
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• pp.1279-1291
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• 2000

The main objectives of this study were to analyze the concept of hope, so to provide basic data to develop a valid instrument to measure hope, and to develop hope enhancing nursing intervention a program for cancer patients. The hybrid model approach was applied in three phases, the theoretical phase, the empirical phase, and the analytic phase. The study was developed on universal attributes explaining generalized hope and specific hope, which were revealed in a comprehensive review of the literature. In the empirical phase, eight cancer patients undergoing chemotherapy were interviewed to reveal causes, motivation, and their resource of hope according to The Hope Assessment Guide (Farren, Herth, & Popovich, 1995). In the analytical phase, the results of the two previous stages of the study were compared. The results were as follows : In the theoretical phase, six dimensions of hope emerged; affective, cognitive, behavioral, affiliative, temporal and contextual dimension. The antecedent of hope was loss, crisis, uncertainity, and stress. The consequences were renewal, development of new methods, safety, peace and transcendental competence. In the empirical phase, these six dimensions emerged as theoretical phases were verified and specified as these descriptive terms: feeling, intention, expectation, activity, relation, future- orientation, reality and goal-setting. The antecedent factor of hope was occurrence or recurrence of cancer. The consequence of hope was ability to cope with real condition, feeling of safety and comfort, peace, development of new strategy and recovery of disease. The major content of hope in this phase was related to specific hope, but it was also influenced on by general hope. In the analytic phase, general and specific hope was renamed as trait and state hope. All attributes emerged at the empirical phases, and also emerged at the theoretical phase. However, cognitive and contextual dimensions were revised and specified. In conclusion, the concept of hope is divided into trait hope and state hope, and state hope is an anticipatory expectation that occurs at the time of a stressful stimulus, such as being diagnosed with cancer. Hope is a multidimensional dynamic energized mental state which has the dimensions of affective, cognitive, behavioral, affiliative, temporal and contextual. There should be further studies to develope the state and trait hope scale according to definition and attributes of hope investigated in this study. In addition, considering results of the empirical phase, the family is very a important factor as a resource of hope, so it is necessary to consider family in implementing a nursing intervention program to enhance hope.

• Journal of the Korean Society for Library and Information Science
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• v.33 no.1
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• pp.67-86
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• 1999

It needs to be considered that citing is net a static process but a dynamic process which is to produce to reproduce and to distribute knowledge by the interaction between societies surrounding the citer. This study begins by briefly acknowledging that citation is a universal practice in terms of establishing citer's own basis of research on the basis of the relation to previous studies and persuadeing potential citer to cite his/her research product. This study, however, is a preliminary attempt to examine the premise that although citing is a unversal practice. but citer motivations can be influenced by various citation environmental contexts surrounding the citer. This study presented general citation motivations derived from previous studies: (1) substantial motivations - conceptional and methodological citations 2) persuasive motivations - positive, applied, and negative citations, (3) perfunctory motivations - perfunctory and bibliographic citations, and (4) social relation motivations - personal connections and knowledge familiarity citations. In addition, this study identified citation environment factors affecting these citation motivations: (1) citer and documentation factor, (2) social and cultural environment, (3) information environment, and (4) international knowledge system environment. Each citation environment factor presented should be interpreted not as a separate factor, but rather as a close interrelation among these environment factors, Finally, the model of the citation environment factors developed in this study was discussed in the aspects of the relationship between citation motivations and their citation environment factors. This study suggested that further research should be conducted in order to examine these relationships more empirically and citation should be considered as a social product reflecting the interaction between citer and various citation environments.

• Journal of Biomedical Engineering Research
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• v.24 no.6 s.81
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• pp.515-522
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• 2003

Pharynx is a system transporting foods by peristaltic motion(contraction and expansion movement! into the esophagus and functioning as airway passages. In this study, structural changes of pharyngeal dysfunction are analyzed by biomechanical model using CT and FEM(finite clement method). Loading condition was assumed that equal pressure was loaded sequentially to inside of pharyngeal tissue. In order to analyze the pharyngeal muscular dysfunction by biomechanical model. the pharyngeal dysfunctions was classified into 3 cases. Taking into account the clinical complication by neuromuscular symptoms such as pharyngeal dysfunction after stroke. we assumed that a change of material property is caused by muscular tissue stiffness. A deformation of cross sectional area of the pharynx is analyzed increasing the stiffness $25\%,\;50\%,\;75\%$ in each case on the basis of stress-strain relationship. Based on three-dimensional reconstruction of pharyngeal structure using limited factor - techniques and the optimization procedure by means of inverse dynamic approach. the biomechanical model of the human pharynx is implemented. The results may be used as clinical index illustrating the degree of pharyngeal muscular dysfunction. This study may be used as useful diagnostic model in discovering early deglutitory impediment caused by physiological or pathological pharyngeal dysfunction.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.743-752
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• 2009

One of the major problems associated with operation of domestic sewer lines involves hydraulic problems such as insufficient conveyance capacity, exceeding maximum velocity, and deficiency of minimum velocity. It has also been pointed out that influent concentration lower than design concentration of pollutants, which is mainly caused by unidentified inflow and infiltration, degrades the operational efficiency of many sewage treatment plants (STPs). A computer-added analysis method supporting a coupled simulation of sewage quality and quantity is essentially required to evaluate the status of existing STPs and to improve their efficiency by a proper sewer rehabilitation work. In this study, dynamic water quality simulations were conducted using MOUSE TRAP to investigate the principal parameters that governs the changes of BOD, ${NH_4}^+$, and ${PO_4}^{3-}$3- concentrations within the sewer networks based on data acquired through on-site and laboratory measurements. The BOD, ${NH_4}^+$ and ${PO_4}^{3-}$3- concentrations estimated by MOUSE TRAP was lower than theoretical pollution loads because of sedimentation and decomposition in the sewer. The results revealed that sedimentation is a most important factor than other biological reactions in decreasing pollutant load in the sewers of C-city. The sensitivity analysis of parameters pertaining to water quality changes indicated that the effect of the BOD decay rate, the initial DO concentration, the half-saturation coefficient of dissolved BOD, and the initial sediment depth is marginal. However, the influence of settling rate and temperature is relatively high because sedimentation and precipitation, rather than biological degradation, are dominant processes that affect water quality in the study sewer systems.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.1
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• pp.116-126
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• 2006

The purpose of this study is to analyze the growing course of Busan, Gimhae and Jinhae and further find patterns of the urban growth. This study shows that patterns of the urban growth differ from city to city, being influenced by the city's characteristics. Acknowledging this fact would help the decision maker to determine the developing plan of the urban. The methodology for this study is as follows; Fuzzy set concept is applied to minimize the data loss. At the same time, the AHP is used to give a relative weight to each factor. In order to be able to manage the change based on the dynamic model and time, Cellular Automata is introduced to simulate the growth of urban. The results show that the pattern of Gimhae's and Jinhae's growth is the same, whereas that of Busan is different from them. That is to say, each city has regional characteristics. And the pattern of the urban growth is influenced by the regional conditions of the city.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.101-110
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• 2012

In recent days, lots of social commerce newly emerged business types of e-commerces are on the basis of social network. Therefore social commerce with social network might be powerful communication channel among customers and has suggested new paradigm in transaction model on the internet. In general, major roles of social commerce sites are to promote transaction with high discount rate and/or lots of event and to activate markets of local area. As characteristics of social commerce such as dynamic, rapid, and open, this research was assumed that design factors of sites that are different from existing e-commerce sites might be influential elements in decision making of purchase. This research is to empirically investigate which factors affect purchase decision making behaviors for 20s respondents who are major users of social commerce services. As a result major factor, easy-to-use, affecting decision making factors was identified and this result can give implication to researchers and persons in charge of fields who have interests in commerce site design and upgrade.

• Journal of Environmental Science International
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• v.29 no.1
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• pp.1-13
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• 2020

Recently, a heavy rainfall with high spatial variation occurred frequently in the Korean Peninsula. The meteorological event that occurred in Busan on 3 May 2016 is characterized by heavy rain in a limited area. In order to clarify the reason of large spatial variation associated with mountain height and location of low level jet, several numerical experiments were carried out using the dynamic meteorological Weather Research and Forecasting (WRF) model. In this case study, the raised topography of Mount Geumjeong increased a barrier effect and air uplifting due to topographic forcing on the windward side. As a result, wind speed reduced and precipitation increased. In contrast, on the downwind side, the wind speed was slightly faster and since the total amount of water vapor is limited, the precipitation on the downwind side reduced. Numerical experiments on shifting the location of the lower jet demonstrated that if the lower jet is close to the mountain, its core becomes higher due to the effect of friction. Additionally, the water vapor convergence around the mountain increased and eventually the precipitation also increased in the area near the mountain. Hence, the location information of the lower jet is an important factor for accurately predicting precipitation.