• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1389-1408
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• 2021

Proof-of-Work (PoW) is the first and still most common consensus protocol in blockchain. But it is costly and energy intensive, aiming at addressing these problems, we propose a consensus algorithm named Proof-of-Work-and-Block-Compression (PoW-BC). PoW-BC is an improvement of PoW to compress blocks and adjust consensus parameters. The algorithm is designed to encourage the reduction of block size, which improves transmission efficiency and reduces disk space for storing blocks. The transaction optimization model and block compression model are proposed to compress block data with a smaller compression ratio and less compression/ decompression duration. Block compression ratio is used to adjust mining difficulty and transaction count of PoW-BC consensus protocol according to the consensus parameters adjustment model. Through experiment and analysis, it shows that PoW-BC improves transaction throughput, and reduces block interval and energy consumption.

• 운동영양학회지
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• 제24권4호
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• pp.1-6
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• 2020

[Purpose] Exercise is a fundamental way to maintain and improve health and physical fitness. Many human studies have demonstrated the beneficial effects of exercise on various biological parameters. However, studies investigating the effects of exercise in dogs are limited. This review summarized the current data from studies that examined the effects of different exercise conditions (treadmill vs. non-treadmill and acute vs. chronic) on physiological and hematological parameters in dogs. [Methods] Papers addressing the effects of exercise in dogs published from January 2000 to October 2020 were retrieved from the online databases of Scopus, Google Scholar, and PubMed and were selected and reviewed. [Results] The exercise conditions differentially affected physiological and hematological responses and adaptation in dogs. Therefore, the development and comprehensive evaluation of scientific exercise programs for dogs are necessary. [Conclusion] The dog would be a valuable exercise science animal model, and studies aiming at the optimal health, well-being, and quality of life of dogs need to be conducted.

• 대한인간공학회지
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• 제26권2호
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• pp.45-59
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• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.101-108
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• 2016

The RCS characteristics of stealth modified three-surface aircraft are analyzed in this paper. Prototype A is built with CATIA software and the three-dimensional digital models of modified stealth three-surface B and C are also designed based on carrier-based aircraft Su-33; the numerical simulation of RCS characteristics of three-surface aircraft is conducted with RCSAnsys software based on physical optics method and the method of equivalent currents; The following results are obtained by comparative analysis and mathematical statistics: (1) by the use of physical optics method and equivalent electromagnetic current method, the scattering intensity for each part of the model and RCS characteristic of the aircraft can be analyzed efficiently and accurately; (2) compared with model A, the mean RCS value of model B is reduced to 14.1% in forward direction and 48.1% in lateral direction; (3) compared with model A, the mean RCS value of model C decreases to 11.4% in forward direction and 21.6% in lateral direction. The results are expected to provide theoretical basis and technical support to the conceptual design of aircraft and stealth technology research.

• Structural Engineering and Mechanics
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• 제53권3호
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• pp.393-410
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• 2015

Two dimensional numerical models and physical models have been developed to study the highly nonlinear interactions between waves and breakwaters, but several of these models consider the effects of the structural dynamic responses and the shape of the breakwater axis on the wave pressures. In this study, a multi-material Arbitrary Lagrangian Eulerian (ALE) method is developed to simulate the nonlinear interactions between nonlinear waves and elastic seawalls on a coastal rubble mound breakwater, and is validated experimentally. In the experiment, a solitary wave is generated and used with a physical breakwater model. The wave impact is validated computationally using a breakwater - flume coupling model that replicates the physical model. The computational results, including those for the wave pressure and the water-on-deck, are in good agreement with the experimental results. A local breakwater model is used to discuss the effects of the structural dynamic response and different design parameters of the breakwater on wave loads, together with pressure distribution up the seawall. A large-scale breakwater model is used to numerically study the large-scale wave impact problem and the horizontal distribution of the wave pressures on the seawalls.

• 대한간호학회지
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• 제29권4호
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• pp.829-840
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• 1999

This study was conducted to construct a hypothetical model of depression in Korean adolescent women and validate the fit of the model to the empirical data. The data were collected from 345 high school girls in Seoul, from May 1 to June 30, 1998. The instruments were the Body Mass Index, Physical Satisfaction Scale, Family Adaptatibility and Cohesion Evaluation Scale III, Family Satisfaction Scale, CES-D and School Adptation Scale. The data were analyzed using descriptive statistics with the pc -SAS program. The Linear Structural Relationship(LISREL) modeling process was used to find the best fit model which would predict the causal relationships among the variables. The overall fit of the hypothetical model to the data was moderate ［X$^2$＝69.6(df＝17, p＝.000), GFI ＝0.95, AGFI＝0.90, RMR＝0.087, NNFI＝0.86, NFI＝0.90］. The predictable variables, especially menstrual symptoms, physical symptoms and family function, had a significant direct effect on depression. but school life adaptation did not have a significant direct effect. These variables explained 18.1% of the total variance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.537-540
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• 2006

Over the past few decades, a considerable number of studies on the durability of concrete have been carried out extensively. A lot of improvements have been achieved especially in modeling of ionic flows. However, the majority of these researches have not dealt with the chloride binding isotherm based on the mechanism, although chloride binding capacity can significantly impact on the total service life of concrete under marine environment. The purpose of this study is to develop the model of chloride binding isotherm based on the individual mechanism. It is well known that chlorides ions in concrete can be present; free chlorides dissolved in the pore solution, chemical bound chlorides reacted with the hydration compounds of cement, and physical bound attracted to the surface of C-S-H grains. First, sub-model for water soluble chloride content is suggested as a function of pore solution and degree of saturation. Second, chemical model is suggested separately to estimate the response of binding capacity due to C-S-H and Friedel's salt. Finally, physical bound chloride content is estimated to consider a surface area of C-S-H nano-grains and the distance limited by the Van der Waals force. The new model of chloride binding isotherm suggested in this study is based on their intrinsic binding mechanisms and hydration reaction of concrete. Accordingly, it is possible to characterize chloride binding isotherm at the arbitrary stage of hydration time and arbitrary location from the surface of concrete. Comparative study with experimental data of published literature is accomplished to validity this model.

• Journal of Power Electronics
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• 제18권6호
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• pp.1771-1779
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• 2018

Modern trams with a super capacitor have gained a lot of attention in recent years due to its reliability, convenience, energy conservation and environmental friendliness. Because of its special charging characteristic, the traditional charging structure and control strategy cannot satisfy its charging requirements. This paper presents a new charging topology for fast charging modern trams with a super capacitor and it designs a controller using continuous control set model predictive control (CCS-MPC). There are three contributions in this paper. First, a new charging structure is designed and its mathematics model is derived. The cascade structure is adopted instead of the parallel structure to simplify the control process and to keep the rated power of the controllable part low. Second, a MPC control strategy is proposed to satisfy the charging characteristic. The optimal control signal can be obtained by solving the designed optimization problem. The optimal control signal is related to the discrete control action. In addition, mapping between the continuous control signal and the discrete control action is designed. Third, a semi-physical experimental platform is built to verify the proposed topology and control method. The simulation model and experiment platform are built to verify the correctness of the new structure and its control method. The results obtained show that the new topology can work effectively.

• 한국의류학회지
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• 제38권4호
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• pp.528-539
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• 2014

This study analyzed the influence of self-construal on sociocultural attitude toward physical appearance, body satisfaction, and appearance management behavior through a structural equation model. The empirical study was based on the response of 369 adult females between the ages of 20 and 49 in Seoul. Self-construal was presented as an independent self-construal and interdependent self-construal, respectively. The sociocultural attitude toward physical appearance as an intermediate variable in the research model was composed of two sub-factors that included internalization and awareness. The other (body satisfaction) was measured by two factors (body and face). Appearance management behavior (as a final outcome variable) were composed of various factors that included clothing concern, skin care, hair care, and weight training. The findings of this study were: 1) the effect of independent self-construal on the sociocultural attitude toward physical appearance was not significantly meaningful; however, interdependent self-construal influenced it positively. 2) Sociocultural attitude toward physical appearance appeared to have a negative effect on body satisfaction. 3) The body satisfaction also had a negative effect on appearance management behavior in this study.

• 한국항행학회논문지
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• 제13권3호
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• pp.351-357
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• 2009

본 논문에서는 QualNet에 Matlab으로 구현해 놓은 WAVE 채널 모델과 물리계층 시뮬레이션 모듈을 효과적으로 연동시킬 수 있는 방안을 연구하였다. 우선, QualNet 시뮬레이터에서 사용하는 간소화된 무선 물리계층 및 통신매체의 구현 방법에 대해 검토 후, QualNet 네트워크 시뮬레이터가 상세한 다중경로 페이딩 모델과 IEEE802.11p 통신 모뎀이 구현된 이종의 물리계층 시뮬레이션 모듈을 도입하기 위한 실질적인 방안을 제시하였다. 본 논문의 결과는 차세대 DSRC 규격인 WAVE를 위한 상위계층에서부터 하위 물리계층 링크를 통합시뮬레이션 하는 링크 시뮬레이션 기법으로 활용될 것이다.