• Structural Engineering and Mechanics
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• v.50 no.5
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• pp.589-603
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• 2014

Expressions for determining the value of the impact force as reported in the literature and incorporated into code provisions are essentially quasi-static forces for emulating deflection. Quasi-static forces are not to be confused with contact force which is generated in the vicinity of the point of contact between the impactor and target, and contact force is responsible for damage featuring perforation and denting. The distinction between the two types of forces in the context of impact actions is not widely understood and few guidelines have been developed for their estimation. The value of the contact force can be many times higher than that of the quasi-static force and lasts for a matter of a few milli-seconds whereas the deflection of the target can evolve over a much longer time span. The stiffer the impactor the shorter the period of time to deliver the impulsive action onto the target and consequently the higher the peak value of the contact force. This phenomenon is not taken into account by any contemporary codified method of modelling impact actions which are mostly based on the considerations of momentum and energy principles. Computer software such as LS-DYNA has the capability of predicting contact force but the dynamic stiffness parameters of the impactor material which is required for input into the program has not been documented for debris materials. The alternative, direct, approach for an accurate evaluation of the damage potential of an impact scenario is by physical experimentation. However, it can be difficult to extrapolate observations from laboratory testings to behaviour in real scenarios when the underlying principles have not been established. Contact force is also difficult to measure. Thus, the amount of useful information that can be retrieved from isolated impact experiments to guide design and to quantify risk is very limited. In this paper, practical methods for estimating the amount of contact force that can be generated by the impact of a fallen debris object are introduced along with the governing principles. An experimental-calibration procedure forming part of the assessment procedure has also been verified.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.145-151
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• 2021

This study aimed to investigate the efficient conduct of HA coating on Ti Gr4 for the practical use of medical device. Ti Gr4 alloy specimens measuring 𝜱 25mm × 1mm were sprayed with hydroxyapatite using thermal spray according to ASTM F1185-88. The surface was evaluated at #120, #400, #1,000 sandpaper and barrel finishing. Each coating properties was analyzed using SEM, UTS 20,000psi cap. and in vitro cytotoxicity. Surface morphology consists of well molten particles with very little resolidified or unmolten areas. The average Ca/P ratio is 1.74 which is in good agreement with theoretical value of 1.67. The average roughness Ra is very representative of roughness of specimen. The coatings are dense and well adhered to the substrate. The average bond strength was 61.74 MPa with a standard deviation of 4.06 which indicates fairly reliable results for ASTM 633 type tests. Variations in results from jig design, epoxy used, crosshead speeds etc. in vitro cytotoxicity result had a Grade 3. The results of the study are expected to be helpful in osseointegration and plasma-spray HA coated Ti Gr4 are more satisfactory in HA coating thickness elevation which is preferable to any other system.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.24-32
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• 2021

Personal Air Vehicle (PAV), Cargo UAS (Cargo UAS), and existing manned and unmanned aircraft are key vehicles for urban air mobility (UAM), and should demonstrate compatibility for the design of aircraft systems. The safety assessment required by for certification to ensure safety and reliability should be systematically performed throughout the entire cycle from the beginning of the aircraft development process. However, with the increasing complexity of safety critical aviation systems and the application of state-of-the-art systems, conventional experience-based and procedural-based safety evaluation methods make ir difficult to objectively assess safety requirements and system safety. Therefore, Model-Based Safety Assessment (MBSA) using modeling and simulation techniques is actively being studied at domestic and foreign countries to address these problems. In this paper, we propose a Model-Based Safety Evaluation framework utilizing modeling and simulation-based integrated flight simulators. Our case studies on the Traffic Collision Availability System (TCAS) and Wheel Brake System (WBS) confirmed that they are practical for future safety assessments.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.39 no.2
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• pp.39-49
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• 2021

This study was conducted to establish practical goals for the viewing environment and interpretation and delivery system of cultural heritage and to create an viewing environment according to the classification of cultural heritage types, and the conclusions reached are as follows. First, five goals were set based on the international basic principles of the cultural heritage viewing environment and interpretation and delivery system. Second, based on the set goals, cultural heritage was classified into the first type 'disappeared and hidden heritage', the second type 'stuffed memory heritage', and the third type 'living memory heritage'. Third, the directions for creating the viewing environment for each type of cultural heritage were suggested. The first type has to be able to properly convey cultural heritage to visitors through excavation and digital technology. The second type needs a plan to deliver tangible and intangible values by combining various digital technologies with actual cultural heritage. The third type should emphasize the role of local residents in effectively enjoying the tangible and intangible values ??that already exist. Fourth, it proposed comprehensive considerations in the establishment of the cultural heritage viewing environment and interpretation and delivery system. Based on dynamic and sustainable heritage management, cultural heritage viewing should be valuable, satisfying and enjoyable. In addition, local communities should be actively involved, and tourism and conservation activities should be able to benefit the community. Establishment of a viewing environment should protect and strengthen the authenticity of cultural heritage.

• Journal of Korea Trade
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• v.24 no.8
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• pp.101-120
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• 2020

Purpose - The buyer's right to withhold performance is a useful and important self-help remedy to protect himself from the seller's breach of contract, and it is also the coercive means to induce the seller to perform his part of contract. However, the buyer's exercise of such a right often exposes himself to the risk of breaching the contract. This is generally due to his ignorance when he is entitled to the right and also uncertainties inherent in the law. Therefore, the purpose of this paper is to examine what the requirements should be fulfilled before the buyer exercises the right for the seller's actual breach of contract. Design/methodology - In order to achieve the purposes of the study, it executes a comparative study of the rules as to the requirements for the buyer's right to withhold performance for the seller's actual non-performance under the CISG and the CESL. It mainly focuses on performance due, the seller's non-performance, the buyer's readiness to perform and the requirement of notice. Findings - The main findings of this comparative study can be summarized as follows: Although the CISG has no expressive provision for the buyer's general right to withhold performance for the seller's actual non-performance, it may be inferred from the general principles the CISG underlies, synallagmatic nature of the contract. In addition, it can be drawn by analogy from relevant provisions of the CISG. On the other hand, the CESL expressively provides that the buyer has a general right to withhold performance where the seller fails to tender performance or perform the contract. Therefore, it seems that the position of CESL is rather easier and more apparent to allow the buyer to withhold performance for the seller's non-performance. Originality/value - Most of the existing studies on the right to withhold performance under the CISG have centered on the right to withhold performance for an anticipatory breach of contract. On the other hand, there have been few prior studies on the right to withhold performance for the actual nonperformance during a contractual period of performance. Therefore, this paper examined the requirements for the buyer's right to withhold performance under the CISG and the CESL in a comparative way for the seller's actual breach of obligation. In this conclusion, it may provide practical and legal considerations and implications for business people who are not certain about the right to withhold performance.

• Journal of Korea Trade
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• v.24 no.1
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• pp.82-98
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• 2020

Purpose - This study aims to overcome the limitations of existing studies, which linearly determine the precedence factors of competency in overseas subsidiaries. The research objectives are as follows. First, what kind of nonlinear effects does the level of control held by Korean headquarters over foreign subsidiaries have in terms of competency in the subsidiaries? Second, what kind of nonlinear effects do the local experiences of overseas subsidiaries have on their competency? Design/methodology - With data on Korean multinational corporations (MNCs), this paper analyzes the effects of control levels of headquarters (HQs) and host-country experiences of foreign subsidiaries regarding competency in overseas subsidiaries. In particular, this study focuses on nonlinear models, differentiating it from previous studies. In order to examine research hypotheses, this study conducted a survey of overseas subsidiaries of Korean corporations. Surveys were conducted through various methods including e-mail, online questionnaires, fax, and telephone calls. Copies of the questionnaire were distributed to a total of 2,246 overseas subsidiaries, and 409 completed responses were collected. Excluding 15 copies that were insufficiently answered, responses from a total of 394 copies were used for analysis. Findings - This study presents the following results. First, there is a U-shaped relationship between levels of HQ control and competency in foreign subsidiaries. This means that higher levels of HQ control negatively impact the competency levels of subsidiaries because strict control undermines autonomy in subsidiaries. However, if the level of HQ control exceeds a certain point, then the transfer of knowledge between HQs and subsidiaries is facilitated. Knowledge transferred from HQs can be used as prior knowledge by foreign subsidiaries to the benefit of all parties. Accordingly, knowledge transfer negates the negative effects of excessive HQ control and positively affects competency in subsidiaries. Second, there is an inverted U-shaped relationship between the local (host-country) experiences of subsidiaries and competency in foreign subsidiaries. This means that foreign subsidiaries can overcome the liabilities of foreignness and contribute to capability building by accumulating unique knowledge about their host countries. However, if local experiences accumulate excessively beyond a certain point, then the host country-specific experiences of foreign subsidiaries will offset the benefits discussed above. Excessive local experiences not only increase organizational inertia, but also create a problem of goal incongruence due to information asymmetry between HQs and subsidiaries. Therefore, excessive local experiences have negative effects on competency in foreign subsidiaries. Originality/value - This study suggests the following implications. First, unlike existing studies based mainly on linear models, this study presents important theoretical implications in its focus on nonlinear models and its analysis of the effects of HQ control and local experiences on competency in foreign subsidiaries from perspectives of organizational learning theory and agency theory. Second, in terms of practical implications, the results of this study suggest that optimally raising levels of HQ control and managing the local experiences of subsidiaries without increasing organizational inertia is important for enhancing competency in foreign subsidiaries.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.389-399
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• 2021

The purpose of this study was to explore the domestic and overseas home modification policies, and review the direction of domestic home modification policies to enable 'Aging In Place; AIP' and the competencies required of occupational therapist as and expert in home modification. In order to expand occupational therapy for domestic home modification and strengthen occupational therapist competency, it is required to establish a clear and practical home modification process that reflects the design and intervention of occupational therapy. Appropriate selection and standardization of the evaluation tools that identifies the needs of the elderly and reflects the characteristics of domestic housing types are also required. In addition, it is necessary to understand policies and systems, and endeavour to establish a relevant knowledge base for communication and cooperation with experts in other fields. In terms of the policy, there is a need for the home modification support system that allows the elderly to adapt to their aging regardless of their income level, beyond the existing support system, which was implemented mainly for low-income people and disabled. In addition, as in overseas cases, the efforts need to be made to provide various and efficient measures, such as support for barrier-free housing, expansion of the scope of support through cooperation between the national government and local governments, low-interest loans and tax reductions, and establishment of governance with organizations and institutions related to home modification services.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.129-134
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• 2021

Recently, the demand for electricity is gradually increasing due to the rapid industrial development and the improvement of living standards. In the case of Korea, which is highly dependent on fossil fuels due to such a surge in electricity demand, reduction and freezing of greenhouse gas emissions due to international environmental regulations will immediately lead to a contraction in industrial activities. Accordingly, there are many difficulties in competition with advanced countries that want to link the environment with the country's industrial production activities, and the development of alternative energy as a countermeasure is of great interest around the world. Among these new power generation methods, small-scale power generation facilities with relatively small capacity include photovoltaic generation, wind power generation, and fuel cell generation. Among them, the fuel cell attracts the most attention in consideration of continuous operation, high power generation efficiency, and long-term durability, which are important factors for practical use. Therefore, in this paper, the fuel cell power generation system was researched and constructed by designing the power conversion circuit necessary to finally obtain the AC power used in our daily life by using the DC power generated from the fuel cell as an input.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.764-771
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• 2018

Domestic and foreign agricultural environments nowadays are undergoing various changes such as aging of agricultural population, increase of earned population, rapid climate change, diversification of agricultural product distribution structure, depletion of water resources and limited cultivation area. In order to respond to various environmental changes in recent agriculture, practical use of Smart Greenhouse to easily record, store and manage crop production information such as crop growing information, growth environment and agriculture work log, Interest is growing. In this paper, we propose a system that collects the situation information necessary for growth such as temperature, humidity, solar radiation, CO2 concentration, and monitor the collected data, which can be measured in the rhizosphere of the crop. We have developed a system that collects data such as temperature, humidity, radiation, and growth environment data, which are measured by data obtained from the rhizosphere measuring section of a growing crop and measured by a sensor, and transmitted to a wireless communication gateway of 400 MHz. We developed the integrated SW that can monitor the rhythm environment data and visualize the data by using cloud based data. We can monitor by graph format and data format for visualization of data. The existing smart farm managed crops and facilities using only the data within the farm, and this study suggested the most efficient growth environment by collecting and analyzing the weather and growth environment of the farms nationwide.

• The Journal of Society for e-Business Studies
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• v.23 no.4
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• pp.1-17
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• 2018

Recently, most online firms are trying to provide personalized services based on customer's data. However, customers are reluctant to give their information to online firm because of concerns about data breach. Online firms are seeking to increase their trust by ensuring the protection of personal information for customers through privacy seal (e.g. e-privacy) or data breach insurance. This research examines the effects of privacy assurance(i.e. privacy seal, data breach insurance) on consumer behavior in online environment. An experiment based on the hypothetical scenario was conducted using a between-subjects 2 (type of privacy assurance) + 1 (control) design. We found that both privacy seal and data breach insurance increased perceived privacy trust. In addition, privacy seal has a positive effect on the intention to provide personal information through perceived privacy trust. Finally, in the case of the group with a high (low) disposition to trust, higher perceived privacy trust is formed through privacy seal (data breach insurance). Theoretical and practical implications are discussed.