• Speech Sciences
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• v.15 no.2
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• pp.145-156
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• 2008

The purpose of this study was to investigate the reason why puberphonia patients revisit hospitals after completion of its treatment and the effect of visual voice therapy on voice improvement. The subject the study included are two puberphonia patients who had been diagnosed by laryngologists. The patients who were diagnosed as puberphonia by the laryngologist and treated by the a speech pathologist, completed their treatment and revisited hospital. The study used laryngoscopy, acoustic and aerodynamic analysis before and after voice treatment to investigate what change happens and why generalization of treatment effect did not occur naturally in the daily life. Their voices of pre-therapy and post-therapy were analyzed on the aspects of acoustics, aerodynamics and laryngeal endoscopy. As a result, it was found that fundamental frequency(Fo) was significantly lowered in respect of acoustic change and maximum phonation time(MPT) was increased to some extent in respect of aerodynamic change. In addition, there was a laryngoscopic change and commissure glottic chink disappeared generally in the phonation. The reason why the generalization did not occur naturally in one’s daily routine was mainly due to the fact that high-pitched voicing was used for a long time. Other than that reason, negative reaction or attitude of surrounding people and lack of confidence were to blame for failure of generalization.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.56.1-56.1
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• 2018

Tidal disruption events (TDEs) provide evidence for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. TDEs occur when a star on a parabolic orbit approaches close enough to a SMBH to be disrupted by the tidal force of the SMBH. The subsequent super-Eddington accretion of stellar debris falling back to the SMBH produces a characteristic flare lasting several months. The theoretically expected bolometric light curve decays with time as proportional to $t^{-5/3}$. However, the light curves observed in most of the optical-UV TDEs deviate from the $t^{-5/3}$ decay rate especially at early time, while the light curves of some soft-X-ray TDEs are overall in good agreement with the $t^{-5/3}$ law. Therefore, it is required to construct the theoretical model for explaining these light curve variations consistently. In this paper, we revisit the mass fallback rates analytically and semi-analytically by taking account of the structure of the star, which is simply modeled by the polytrope. We find the relation between a polytropic index and the power law index of the mass fallback rate. We also discuss whether and how the decay curves, which we derived, fit the observed ones.

• Korean Journal of Remote Sensing
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• v.37 no.4
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• pp.789-802
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• 2021

Synthetic Aperture Radar (SAR) at C-band is an ideal remote sensing system for crop monitoring owing to its short wavelength, which interacts with the upper parts of the crop canopy. This study evaluated the potential of dual polarimetric Sentinel-1 at C-band for monitoring rice phenology. Rice phenological variations occur in a short period. Hence, the short revisit time of Sentinel-1 SAR system can facilitate the tracking of short-term temporal morphological variations in rice crop growth. The sensitivity of SAR backscattering coefficients, backscattering ratio, and polarimetric decomposition parameters on rice phenological stages were investigated through a time-series analysis of 33 Sentinel-1 Single Look Complex images collected from 10th April to 25th October 2020 in Gimhae, South Korea. Based on the observed temporal variations in SAR parameters, we could identify and distinguish the phenological stages of the Gimhae rice growth cycle. The backscattering coefficient in VH polarisation and polarimetric decomposition parameters showed high sensitivity to rice growth. However, amongst SAR parameters estimated in this study, the VH backscattering coefficient realistically identifies all phenological stages, and its temporal variation patterns are preserved in both Sentinel-1A (S1A) and Sentinel-1B (S1B). Polarimetric decomposition parameters exhibited some offsets in successive acquisitions from S1A and S1B. Further studies with data collected from various incidence angles are crucial to determine the impact of different incidence angles on polarimetric decomposition parameters in rice paddy fields.

• The Journal of the Korean Institute of Forest Recreation
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• v.22 no.4
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• pp.23-33
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• 2018

The purpose of this research is to develop basic materials useful for the visiting management policies' establishment of national parks by analyzing the characteristics of and satisfaction with the visit to Hallyeohaesang National Park according to travel routes. For this, a total of 671 visitors to Hallyeohaesang National Park were recruited and field surveys were conducted three times in spring, summer, and fall from March to November 2017. The Hallyeohaesang national park's visitors were surveyed using a self-administered questionnaire about visitor characteristics (ex: motivation of visiting, travel routes, travel time, and participating activities, etc.) and satisfaction (ex: satisfaction with the visit, intention to revisit, and intention to recommend). SPSS 21.0 program was used for the statistical analysis: frequency analysis and independent-samples t-test analysis. As a result of analysis the motivation of visiting, those who visited only Hallyeohaesang National Park (a single destination) showed a mean value statistically significantly higher level in health improvement and vacation, relaxation, and healing compared to those who had visited or would visit other places along with Hallyeohaesang National Park (multi-destinations). Single destination visitors spent less time traveling from home to national park than multi-destinations visitors. Those who visited only Hallyeohaesang National Park (as a single destination) showed a mean value statistically higher satisfaction and intention to revisit and recommend. The results of this research have significance in providing basic materials to develop efficient park management policies by studying the characteristics of Hallyeohaesang National Park visitors.

• Journal of Distribution Science
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• v.14 no.2
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• pp.123-133
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• 2016

Purpose - Understanding how service convenience drives shopping performance is imperative for retailers such as department and large discount stores. Retailers have to enhance shopping productivity by reducing the costs of shopping, as convenience triggers customers' perceived shopping value, leading to customer satisfaction, and ultimately patronage behavior. Consumers, generally considering time as a scarce resource, are more sensitive to the time costs of tasks in regard to shopping trip, differently from forming perceptions of convenience in time orientation. Therefore, this study attempts to examine the moderating effects of consumers' time orientation on the relationships among service convenience of retailers and shopping performances such as shopping value and service performances. Research design, data, and methodology - The department and discount store chains were chosen as the point of analysis in this study. Data were collected from a survey of real-life consumers and all respondents were screened to ensure only those who had visited in the department and discount store chains within past six month prior to the day of data collection. Out of 600 self-reported surveys that were distributed, a total of 530 responses were returned and after excluding 20 incomplete responses, the final sample size was 510. The three hypotheses were proposed and tested in this study. The one hypothesis was on the moderating effects of time orientation for the effects of service convenience on shopping value (hedonic and utilitarian shopping value). The other two hypotheses were on the comparisons between high and low time-oriented customers with the effects in shopping value from service performance. Hierarchical moderated regression analysis was used to test the hypotheses. Results - The results suggest that the effect of service convenience on utilitarian shopping value and the positive effect of utilitarian shopping value on customer satisfaction are greater in low time orientation than high time orientation customers. Conversely, when customers are highly oriented toward time, the effects of hedonic shopping value on customer satisfaction and revisit intention are greater than for customers who are lowly oriented toward time. Conclusions - This study has two-fold significance. First, this study contributes to the consumer behavior and services marketing literature by incorporating customers' time orientation into the service convenience-shopping performance. Although the effect of service convenience on shopping performance might differ from customers' perceptions concerning shopping, there has been little investigation or comparison between customers' perception on time. This study is a first attempt to consider how the effects of service convenience on shopping value and service performance vary with differing levels of customers' time orientation. This study advances prior studies by showing that the service convenience-shopping value and service convenience-service performance relationships vary across different combinations of the customer's time orientation. The findings of this study suggest that the retailers need to enhance the experiential aspects of the stores for their high time-oriented customers. Conversely, for the low time-oriented customers, the retailers should boost the visual distinctiveness and ease of store navigation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.752-759
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• 2012

This paper presents a mission orbit design method for spacecraft which use the sun-synchronous and ground repeat orbits. In this work, we have proposed a new design procedure, "Nonlinear simulation-based numerical optimization technique" using the commercial S/W's such as STK (Satellite Tool kit) and Matlab, which are widely adopted S/W's in the area of orbital mechanics and engineering analysis. Inclusion of all the perturbation effects on the spacecraft not only can more precisely satisfy the mission requirements for sun-synchronicity and repeated ground track, and also operational requirements such as minimum change in the S/C local time, maximization of the contact time with a specified ground station, etc. can be appropriately considered. Design examples for LEO sun-synchronous mission are presented to demonstrate the usefulness of the proposed method in this paper.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.803-816
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• 2014

Defense-in-depth is a fundamental safety principle for the design and operation of nuclear power plants. Despite its general appeal, defense-in-depth is not without its drawbacks, which include its potential for concealing the occurrence of hazardous states in a system, and more generally rendering the latter more opaque for its operators and managers, thus resulting in safety blind spots. This in turn translates into a shrinking of the time window available for operators to identify an unfolding hazardous condition or situation and intervene to abate it. To prevent this drawback from materializing, we propose in this work a novel safety principle termed "observability-in-depth". We characterize it as the set of provisions technical, operational, and organizational designed to enable the monitoring and identification of emerging hazardous conditions and accident pathogens in real-time and over different time-scales. Observability-in-depth also requires the monitoring of conditions of all safety barriers that implement defense-in-depth; and in so doing it supports sensemaking of identified hazardous conditions, and the understanding of potential accident sequences that might follow (how they can propagate). Observability-in-depth is thus an information-centric principle, and its importance in accident prevention is in the value of the information it provides and actions or safety interventions it spurs. We examine several "event reports" from the U.S. Nuclear Regulatory Commission database, which illustrate specific instances of violation of the observability-in-depth safety principle and the consequences that followed (e.g., unmonitored releases and loss of containments). We also revisit the Three Mile Island accident in light of the proposed principle, and identify causes and consequences of the lack of observability-in-depth related to this accident sequence. We illustrate both the benefits of adopting the observability-in-depth safety principle and the adverse consequences when this principle is violated or not implemented. This work constitutes a first step in the development of the observability-in-depth safety principle, and we hope this effort invites other researchers and safety professionals to further explore and develop this principle and its implementation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.6
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• pp.401-412
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• 2022

In this study, we investigated the design methods of satellite constellations to conduct near-real-time surveillance reconnaissance of the Korean Peninsula. Also, we designed satellite constellations utilizing the Walker-Delta method and repeat-ground-track method, and taking into account the target area and the feasible number of satellites. The constrains of the Electro-Optical and Synthetic Aperture Radar equipment were also considered in performance analysis. As a result, the designed constellation has mean revisit time of less than 30 min which enables near-real-time surveillance reconnaissance of the Korean Peninsula. This research provides the strategy to design the satellite constellation for reconnaissance. Furthermore, it contributes to suggesting an operating strategy for micro-satellites constellation and guidelines for establishing space force.

• The Journal of the Korea Contents Association
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• v.12 no.10
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• pp.466-479
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• 2012

Temple stay has increased fast in the quantitative part recently and it is tourism goods with cultural value as a kind of religion tourism. It is thought that the qualitative development is accompanied with quantitative development at this time. So, in order to increase qualitative improvement, it is needed to confirm mutual relationships among religious involvement, satisfaction factors of performance and behavior intentions of people who takes part in temple stay. Also, this paper confirms whether statistical characteristic of population affects religious involvement or not. 3 assumptions are established for these purposes and all of 3 established assumptions are partly adopted through statistical analyses.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.779-789
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• 2012

In the kinetic theory of dense fluids the many-particle collision bracket integral is given in terms of a classical collision operator defined in the phase space. To find an algorithm to compute the collision bracket integrals, we revisit the eigenvalue problem of the Liouville operator and re-examine the method previously reported [Chem. Phys. 1977, 20, 93]. Then we apply the notion and concept of the eigenfunctions of the Liouville operator and knowledge acquired in the study of the eigenfunctions to cast collision bracket integrals into more convenient and suitable forms for numerical simulations. One of the alternative forms is given in the form of time correlation function. This form, on a further manipulation, assumes a form reminiscent of the Chapman- Enskog collision bracket integrals, but for dense gases and liquids as well as solids. In the dilute gas limit it would give rise precisely to the Chapman-Enskog collision bracket integrals for two-particle collision. The alternative forms obtained are more readily amenable to numerical simulation methods than the collision bracket integrals expressed in terms of a classical collision operator, which requires solution of classical Lippmann-Schwinger integral equations. This way, the aforementioned kinetic theory of dense fluids is made fully accessible by numerical computation/simulation methods, and the transport coefficients thereof are made computationally as accessible as those in the linear response theory.