• International Journal of Knowledge Content Development & Technology
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• 제12권1호
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• pp.85-104
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• 2022

In this study, in line with the era of the fourth industrial revolution, general concepts, technologies, trends, and examples of virtual reality and augmented reality were examined, and based on this, a plan that could be applied to libraries in the future was proposed. As a result of the study, first, it is necessary to construct a smart space as an experiential play space that can satisfy cultural desires transcending time and space by providing immersive contents using 4th technology such as VR and AR. Second, it is necessary to expand experiential cultural support services through VR, AR and MR. Third, to develop educational contents based on augmented reality technology. In order to apply and activate virtual reality and augmented reality in libraries in the future, based on a survey of librarians and users of public libraries, a survey on the application status, satisfaction, and demand of current public libraries should be conducted.

• 아태비즈니스연구
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• 제15권2호
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• pp.23-40
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• 2024

Purpose - The purpose of this study is to examine the relation between accruals quality and managers' choice on the type of voluntary disclosure. Design/methodology/approach - Samples of this study are 8,248 firm-year observations listed in Korea Stock Exchange. Poisson regression analysis was hired in order to analyze the association between disclosure frequency and accruals quality because the dependent variables are count data. Findings - First, this study finds that managers' use of non-earnings-related type of voluntary disclosure is negatively related to accruals quality while their use of earnings-related disclosure is positively related to accruals quality. Second, discretionary accruals quality as well as innate accruals quality is significantly associated with disclosure frequency. Research implications or Originality - This study extends the line of research by incorporating the content of voluntary disclosure, earnings- and non-earnings-related information. The results of this study suggest that accruals quality may play a role in the choice of disclosure manner when investigating managers' voluntary disclosure.

• 에너지공학
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• 제17권3호
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• pp.167-174
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• 2008

지중유효열전도율 측정에서는 선형열원 모델이 열응답 시험의 자료 해석에 주로 이용되고 있는 실정이다. 이 선형열원 모델의 응용에서는 해의 신뢰도를 높이기 위하여 일정시간의 초기자료를 폐기하여야 하며 이 일정시간을 본 연구에서는 초기제외시간으로 명명한다. 그런데 이 초기제외시간의 산정에 관하여 뚜렷한 기준이 마련되어 있지 않아 선형열원 모델을 이용한 자료해석에서는 초기제외시간 선정이 다소 주관적이 되는 경향이 있으며 따라서 이 모델의 응용에는 충분한 경험이 필요하다. 무차원 시간 $\tau=5$가 초기제외시간 선정에 한 기준으로 제시되기도 하였으나 이 역시 완전한 선형열원 모델에서 도출되는 매우 이론적인 결과이며 실제 시스템은 이 이론적인 선형열원과 다른 점이 많다. 본 연구에서는 초기제외시간을 선정하는 새로운 방법을 제시한다. 이 방법에서는 먼저 오차해석을 수행하고 그 결과를 토대로 초기제외시간을 결정하게 된다. 본 연구에서는 이 방법을 2개의 현지 시험결과에 적용하여 보았으며 위에 언급한 $\tau=5$에 의한 방법보다 훨씬 더 신뢰성 높은 결과를 도출할 수 있었다(Table 2 참조).

• Journal of Communications and Networks
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• 제17권1호
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• pp.1-11
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• 2015

In this paper, the transmission of an improper-complex second-order stationary data sequence is considered over a strictly band-limited frequency-selective channel. It is assumed that the transmitter employs linear modulation and that the channel output is corrupted by additive proper-complex cyclostationary noise. Under the average transmit power constraint, the problem of minimizing the mean-squared error at the output of a widely linear receiver is formulated in the time domain to find the optimal transmit and receive waveforms. The optimization problem is converted into a frequency-domain problem by using the vectorized Fourier transform technique and put into the form of a double minimization. First, the widely linear receiver is optimized that requires, unlike the linear receiver design with only one waveform, the design of two receive waveforms. Then, the optimal transmit waveform for the linear modulator is derived by introducing the notion of the impropriety frequency function of a discrete-time random process and by performing a line search combined with an iterative algorithm. The optimal solution shows that both the periodic spectral correlation due to the cyclostationarity and the symmetric spectral correlation about the origin due to the impropriety are well exploited.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.337-345
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• 2002

The present study addresses a computational result of unsteady gas flow through a critical nozzle. The axisymmetric, unsteady, compressible, Wavier-Stokes equations are solved using a finite volume method that makes use of the second order upwind scheme for spatial derivatives and the multi-stage Runge-Kutta integral scheme for time derivatives. The steady solutions of the governing equation system are validated with the previous experimental data to ensure that the present computational method is valid to predict the critical nozzle flows. In order to simulate the effects of back pressure fluctuations on the critical nozzle flows, an excited pressure oscillation with an amplitude and frequency is assumed downstream of the exit of the critical nozzle. The results obtained show that for low Reynolds numbers, the unsteady effects of the pressure fluctuations can propagate upstream of the throat of critical nozzle, and thus giving rise to the applicable fluctuations in mass flow rate through the critical nozzle, while for high Reynolds numbers, the pressure signals occurring at the exit of the critical nozzle do not propagate upstream beyond the nozzle throat. For very low Reynolds number, it is found that the sonic line near the throat of the critical nozzle remarkably fluctuateswith time, providing an important mechanism for pressure signals to propagate upstream of the nozzle throat, even in choked flow conditions. The present study is the first investigation to clarify the unsteady effects on the critical nozzle flows.

• Nutrition Research and Practice
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• 제7권1호
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• pp.66-71
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• 2013

This study analyzes important factors of foodservice in school through comparison of students' satisfaction of using foodservice in Korea and US in order to meet students' expectations. The survey was composed of 4 categories including menu, service, hygiene, and facility and it was carried out in both countries to evaluate satisfaction. First, comparison of satisfaction between two countries was made using t-test. Secondly, multiple regression was performed to identify factors affecting satisfaction. As a result Korean students were more satisfied than American students in all aspects. However, regardless of nationality, the top three factors affecting the students' satisfaction were the same. The predictors were food taste (Korean 0.375 and American 0.350), menu variety (Korean 0.305 and American 0.278), and service line (Korean 0.226 and American 0.192). Despite the similarity of the predicators, it can be concluded that the difference in satisfaction level between the two nationscan be explained by the approaches to create comfortable and acceptable changes in schools' foodservice. Korea has been increasing the foodservice quality based on their objectives to provide students comfortable and positive environment when eating nutritious meals. However, US have made their main objectives on making changes to decrease youth obesity. Foodservice improvements according to continuous evaluations and surveys are necessary in order to increase students' satisfaction.

• Journal of Information Processing Systems
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• 제14권2호
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• pp.499-509
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• 2018

Recently, hybrid transactional memory (HyTM) has gained much interest from researchers because it combines the advantages of hardware transactional memory (HTM) and software transactional memory (STM). To provide the concurrency control of transactions, the existing HyTM-based studies use a bloom filter. However, they fail to overcome the typical false positive errors of a bloom filter. Though the existing studies use a global lock, the efficiency of global lock-based memory allocation is significantly low in multi-core environment. In this paper, we propose an efficient hybrid transactional memory scheme using near-optimal retry computation and sophisticated memory management in order to efficiently process transactions in multi-core environment. First, we propose a near-optimal retry computation algorithm that provides an efficient HTM configuration using machine learning algorithms, according to the characteristic of a given workload. Second, we provide an efficient concurrency control for transactions in different environments by using a sophisticated bloom filter. Third, we propose a memory management scheme being optimized for the CPU cache line, in order to provide a fast transaction processing. Finally, it is shown from our performance evaluation that our HyTM scheme achieves up to 2.5 times better performance by using the Stanford transactional applications for multi-processing (STAMP) benchmarks than the state-of-the-art algorithms.

• 한국실내디자인학회논문집
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• 제13권4호
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• pp.110-117
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• 2004

Recently the hospitals or clinics tend to get out of the functional and technological aspect so as to gradually emphasize service for patients. While qualitative rather than quantitative alteration is noticeable, the scale of clinics is getting larger. Especially, the opulence resulted from economic, social and cultural development has enabled more people to visit dermatology or plastic surgery besides treatment for disease. Responding to this tendency, dermatology is focusing on skin beauty, plastic operation, controlling obesity, etc. for women rather than ordinary treatment. Thus, dermatology is in need of space for skin control as well as ordinary treatment, which raises the immediate necessity of new plan for space and interior environment. In order to meet such necessity of dermatology, it is required to fully study and consider the plan for interior space. First, the purpose, scope and method of research will be defined in the introduction. Second, the concept of clinic as well at the characteristic of dermatology will be studied by theoretical investigation. Third, the general concept of dermatology will be analyzed by examining the characteristic of each room in dermatology, the moving line of nurses and patients, the color of dermatology and the design factor of finishing materials through general investigation on dermatology. Fourth, in order to look into the general case of dermatology, the object of examination will be selected for examination through literature and visiting. After examining data, the result will be analyzed and evaluated to prepare the ground for interior plan of dermatology.

• ETRI Journal
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• 제26권4호
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• pp.321-331
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• 2004

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low-level scheduler in the optical network unit (ONU) and a high-level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi-point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah "Ethernet in the first mile" (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.444-449
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• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range) and presented in time domain.