• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.3
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• pp.211-226
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• 2023

As we transition into the post-COVID era, economic activities that were stagnant are regaining momentum. In particular, there is a growing trend of technology entrepreneurship driven by the opportunities of digital transformation in the Fourth Industrial Revolution. However, entrepreneurship education content is struggling to keep up with the rapid pace of technological change. This study aims to emphasize the importance of entrepreneurship mentoring as a crucial component of entrepreneurship education content that requires adaptation and advancement due to the increasing demand for technology entrepreneurship. This study redefines startup mentoring, which is differentiated from general mentoring, at the present time when the demand for startups, which increases with the declining employment rate, increases, and the development of quality startup education contents and securing professional startup mentors are required. According to the start-up stage, it is divided into preliminary entrepreneurs and early entrepreneurs, and the effect of entrepreneurship knowledge and self-efficacy among start-up mentoring functions on entrepreneurial will and mentoring satisfaction is improved by empirically researching the effects of start-up mentoring functions in the case of initial entrepreneurs as a moderating effect. To confirm the importance of entrepreneurship mentoring effect for. To this end, among the mentoring functions, entrepreneurship knowledge and self-efficacy were set as independent variables, and entrepreneurial will and mentoring satisfaction were set as dependent variables. The research model was designed and hypotheses were established. In addition, empirical analysis was conducted by conducting a questionnaire survey on trainees who received entrepreneurship mentoring education at ICCE Startup School and Opus Startup School. To summarize the results of the empirical analysis, first, among the entrepreneurship mentoring functions, entrepreneurship knowledge and self-efficacy were analyzed to have a significant positive (+) effect on entrepreneurial will. Second, among the entrepreneurship mentoring functions, entrepreneurship knowledge and self-efficacy were analyzed to have a significant positive (+) effect on mentoring satisfaction. Third, it was analyzed that entrepreneurship had no significant moderating effect on entrepreneurial knowledge and entrepreneurial will. Fourth, it was analyzed that entrepreneurship had no significant moderating effect on mentoring satisfaction. Fifth, it was found that entrepreneurship had a significant moderating effect between self-efficacy and will to start a business. As a result of the research analysis, the first implication is that the mentoring function in start-up education is analyzed to produce meaningful results for both the initial entrepreneurs and the prospective entrepreneurs in the will to start a business and satisfaction. . Second, it was analyzed that there was no significant relationship between whether a business was started and the mentoring function and effect. However, it was analyzed that the will to start a business through improvement of self-efficacy through mentoring was significantly related to whether or not to start a business. turned out to be helpful. Many start-up education programs currently conducted in Korea educate both early-stage entrepreneurs and prospective entrepreneurs at the same time for reasons such as convenience. However, through the results of this study, even in small-scale entrepreneurship mentoring, it is suggested that customized mentoring through detailed classification such as whether the mentee has started a business can be a method for successful entrepreneurship and high satisfaction of the mentee.

• Explosives and Blasting
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• v.30 no.2
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• pp.29-42
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• 2012

Variables influencing the free face movement due to rock blasting include the physical and mechanical properties, in particular the discontinuity characteristics, explosive type, charge weight, burden, blast-hole spacing, delay time between blast-holes or rows, stemming conditions. These variables also affects the blast vibration, air blast and size of fragmentation. For the design of surface blasting, the priority is given to the safety of nearby buildings. Therefore, blast vibration has to be controlled by analyzing the free face movement at the surface blasting sites and also blasting operation needs to be optimized to improve the fragmentation size. High-speed digital image analysis enables the analyses of the initial movement of free face of rock, stemming optimality, fragment trajectory, face movement direction and velocity as well as the optimal detonator initiation system. Even though The high-speed image analysis technique has been widely used in foreign countries, its applications can hardly be found in Korea. This thesis aims at carrying out a fundamental study for optimizing the blast design and evaluation using the high-speed digital image analysis. A series of experimentation were performed at two large surface blasting sites with the rock type of shale and granite, respectively. Emulsion and ANFO were the explosives used for the study. Based on the digital images analysis, displacement and velocity of the free face were scrutinized along with the analysis fragment size distribution. In addition, AUTODYN, 2-D FEM model, was applied to simulate detonation pressure, detonation velocity, response time for the initiation of the free face movement and face movement shape. The result show that regardless of the rock type, due to the displacement and the movement velocity have the maximum near the center of charged section the free face becomes curved like a bow. Compared with ANFO, the cases with Emulsion result in larger detonation pressure and velocity and faster reaction for the displacement initiation.

• Journal of Hospice and Palliative Care
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• v.13 no.4
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• pp.232-242
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• 2010

Purpose: This study was done to investigate effects of foot massage and supportive communication provided by hospice volunteers on depression, anxiety, and mood of cancer patients who are going under intravenous chemotherapy at out patient department (OPD). Methods: A non-equivalent control group non-synchronized design was used. Sixty-four participants were recruited from out-patients setting in a university hospital by a convenient sampling. Two trained- hospice volunteers first provided regular hospice volunteer service to 34 patients in the control group. Subsequently, foot massage and supportive communication were provided to 30 participants in the experimental group. After the intervention, all participants answered the structured questionnaire with visual analog scales on depression, anxiety, and mood including general characteristics. Data were analyzed using descriptive statistics, two sample t-test, and paired t-test by PASW 17. Results: After the intervention, changes in negative moods, i.e. strain and powerlessness in the experimental group were significantly different from those in control group; strain and powerlessness in the experimental group were significantly decreased by foot massage and supportive communication provided by hospice volunteers. Conclusion: The current findings provide an empirical evidence of a brief and efficacious intervention for cancer patients. Further studies are warranted with larger sample size to validate the effectiveness of foot massage and supportive communication as a solid intervention for cancer patients who are undergoing intravenous chemotherapy at OPD.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.391-398
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• 2012

This paper presents the shear capacities of biaxial hollow slab with donut type hollow sphere. Recently, various types of slab systems which can reduce self-weight of slabs have been studied for increasing constructions of taller and larger building structures. A biaxial hollow slab system is widely known as one of the effective slab system, which can reduce self-weight of slab. According to previous studies, the hollow slab has low shear strength, compared to solid slab. Also, the shear capacities of biaxial hollow slab are influenced by the shapes and materials of hollow spheres. However, the current code does not provide a clear computation method for the shear strength of hollow slab. To verify the shear capacities of this hollow slab, one-way shear tests were performed. Four test specimens were used for test parameters. One was conventional RC slab and others were hollow slabs. The test parameters included two different shapes and materials of plastic balls. The shape parameters were donut and non-donut forms and the material parameters were general plastic and glass fiber plastic. The results showed that the shear strengths varied depending on hollow shapes and materials used in the slab.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.634-639
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• 2020

In general, the stability and response characteristics of the system can be improved by changing the pole position because a nonlinear system can be linearized by the product of a 1st and 2nd order system. Therefore, a controller that moves the pole can be designed in various ways. Among the other methods, LQ control ensures the stability of the system. On the other hand, it is difficult to specify the location of the pole arbitrarily because the desired response characteristic is obtained by selecting the weighting matrix by trial and error. This paper evaluated a method of selecting a weighting matrix of LQ control that moves multiple double poles with Jordan blocks to real poles. The relational equation between the double poles and weighting matrices were derived from the characteristic equation of the Hamiltonian system with a diagonal control weighting matrix and a state weighting matrix represented by two variables (ρ_d, ϕ_d). The Moving-Range was obtained under the condition that the state-weighting matrix becomes a positive semi-definite matrix. This paper proposes a method of selecting poles in this range and calculating the weighting matrices by the relational equation. Numerical examples are presented to show the usefulness of the proposed method.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.481-488
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• 2015

The purpose of this study is to provide analytical method to reasonably predict the overall behavior up to destruction of reinforced concrete panel specimens using high-strength reinforcing bar. A total of 12 specimens of reinforced concrete panels with a wall thickness one-third the size of the actual nuclear containment structures under various loading conditions and design parameters were selected and the analysis was performed using a non-linear finite element analysis program (RCAHEST) was developed by the authors. The mean and coefficient of variation for shear strength at cracking point and maximum shear strength from the experiment and analysis results was predicted 1.03 and 12%, 0.97 and 9%, respectively. For the shear strain at the maximum shear strength from the experiment and analysis results was predicted 0.96 and 30%, respectively. Based on the results, the analysis program that was applied newly modified constitutive equation in this study is judged as having a relatively high reliability for the analysis results.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.21-31
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• 2018

This paper analyzes the displacements of CFRD which was completed by field measurement. It is to understand the deformation behavior of the dam body according to the water level change from the impounding time. And it was compared with numerical analysis results. As a result of measuring the behavior of the dam crest and downstream slope according to impounding, horizontal displacements in axis direction of the dam, upstream and downstream displacements and settlements occurred mostly when the water level reaches about half of the dam height. The displacements continued until the water level reached its maximum. After that, it showed a constant convergence regardless of the water level. Horizontal displacements of the face slab which is the most important in CFRD were similar at all locations. The Horizontal displacements of the face slab showed the trends of increasing in winter and decreasing in summer due to the effect of the outside temperature before impounding. Also, the displacements increased until the water level reached about half of the dam height. After that, they decreased with rising in water level. As a result, the face slab behaviors according to seasonal change after impounding as well as water level condition. It is judged because of the material characteristics of the concrete slab. Numerical analysis showed slightly different maximum settlement and depth of occurrence from the measuring data after construction of the dam. It is considered that this is due to various design and construction differences such as the estimation of input parameters in analysis, construction period, and the layer thickness of construction. For the overall period of the dam, the settlements were mostly completed during the construction period and some settlements occurred in the early days of impounding and then converged.

• Sleep Medicine and Psychophysiology
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• v.23 no.2
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• pp.61-67
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• 2016

Objectives: We aimed to evaluate the effects of mattress type on both objective and subjective sleep quality in healthy good sleepers. Methods: Fifteen healthy good sleepers with a mean age of 30.8 years participated in this study. A randomized crossover trial was carried out using two different mattress types: a standard mattress and a contour coil mattress. After a night of adaptation, all participants were randomized to either a standard mattress or a contour coil mattress. Then, nocturnal polysomnography was conducted for two consecutive nights. Subjective evaluations were obtained using a self-report questionnaire before and after the polysomnographic recording sessions. Results: The polysomnographic showed no differences in total sleep time, sleep stage, or wake time after sleep onset between the two mattress conditions. Of the polysomnographic variables, only sleep onset latency was significantly reduced for the contour coil mattress. Additionally, participants reported better subjective sleep quality when sleeping on the contour coil mattress, according to the questionnaires. Conclusion: The type of mattress might affect not only subjective, but also objective sleep quality, including sleep onset latency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.282-289
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• 2017

The flexural behavior tests of UHPC segmental Box girder which has 160MPa compressive strength and 15.4m length were carried out. The test variables are area of prestressing wires, volume fraction of steel fibers and longitudinal reinforcing bars in upper flange and web. PS tendons which has 32 strands of 15.2mm diameter in lower flange, 24 strands and 14 strands in lower flange were arranged and volume fraction of 2%, 1.5% and 1.0% is used in box girder concrete. UHPFRC box girder which has 32 strands in lower flange showed the over reinforcement and brittle behavior. UHPFRC box girder which has 24 strands showed the similar peak load as 32 strands girder and ductile behavior as large deflection. UHPFRC box girder which has 14 strands showed half of the peak load of 24 strands box girder and ductile behavior. After the application of the formular for the reinforcement index to the behavior of the UHPFRC box girders, reinforcement index does not determine the characteristic of behavior of UHPFRC box girder exactly. So the index should consider the dimension precisely and modify the reference value corresponding to the 0.005 strain of the prestressing strands.