• Smart Structures and Systems
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• v.31 no.3
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• pp.283-299
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• 2023

Structural stability of floating platforms has long since been a crucial issue in the field of marine engineering. Excessive motions would not only deteriorate the operating conditions but also seriously impact the safety, service life, and production efficiency. In recent decades, several control devices have been proposed to reduce unwanted motions, and an attractive one is the tuned heave plate (THP). However, the THP system may reduce or even lose its effectiveness when it is mistuned due to the shift of dominant wave frequency. In the present study, a novel adaptive tuned heave plate (ATHP) is proposed based on inerter by adjusting its inertance, which allows to overcome the limitation of the conventional THP and realize adaptations to the dominant wave frequencies in real time. Specifically, the analytical model of a representative semisubmersible platform (SSP) equipped with an ATHP is created, and the equations of motion are formulated accordingly. Two optimization strategies (i.e., J₁ and J₂ optimizations) are developed to determine the optimum design parameters of ATHP. The control effectiveness of the optimized ATHP is then examined in the frequency domain by comparing to those without control and controlled by the conventional THP. Moreover, parametric analyses are systematically performed to evaluate the influences of the pre-specified frequency ratio, damping ratio, heave plate sizes, peak periods and wave heights on the performance of ATHP. Furthermore, a Simulink model is also developed to examine the control performance of ATHP in the time domain. It is demonstrated that the proposed ATHP could adaptively adjust the optimum inertance-to-mass ratio by tracking the dominant wave frequencies in real time, and the proposed system shows better control performance than the conventional THP.

• Asia Marketing Journal
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• v.14 no.3
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• pp.7-26
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• 2012

The success story of E-mart fascinated many academics and practitioners alike. Though E-mart began as a nameless discount store in Chang-dong, Seoul in 1993, it has transformed itself into a leading distribution company and one of the most powerful brands in Korea. Surprisingly, it achieved the great success against the two crises it met: the national economic crisis and the invasion of the global giant Walmart. The main objective of this case study is to formally examine how E-mart overcame the two crises. More specifically, this case study highlights the ways with which E-mart turned those difficulties into opportunities for growth. In our examination of the E-mart case, we could clearly see E-mart's competence and spirit that allowed it to turn crises into advantageous opportunities. E-mart attracted the customers who wanted value-oriented consumption by its positioning as the "Lowest price discount store", when consumer sentiment was frozen under the economic crisis. Furthermore, when a large-scale foreign discount store like Walmart entered the Korea market, E-mart built its core competencies as the 'Korean style discount store'. These ingenious positioning and efforts resulted in E-mart taking over their archrival, Walmart, and forced the global Goliath to exit the Korean market. The case of E-mart's effective crisis management teaches many important lessons and a few core lessons that apply to many companies. One such lesson is the importance of positioning which enabled E-mart to turn crises into opportunities. Granted, the strategy of positioning as the 'Korean style discount store', or 'Lowest price discount store' was possible due to overall support with cost reduction, development and management of their own system, an apprentice educate system, etc. based on an excellent selection of location of the store and efficient distribution systems. Still, the positioning strategy of E-mart was truly ground breaking in distancing itself from its competitors. The lessons from E-mart will help those companies currently in a stagnant situation or a crisis to turn their obstacles into great success.

• Knowledge Management Research
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• v.24 no.3
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• pp.127-148
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• 2023

Traditional Business Intelligence environment is limited to support the rapidly changing businesses and the exponential growth of data in both volume and complexity of data. Companies should shift their business intelligence environment into Self-Service Business Intelligence (SSBI) environment in order to make smarter and faster decisions. However, firms seem to face various challenges in implementing and leveraging the effective business intelligence system, and academics do not provide sufficient studies related including the success factors of SSBI. This study analyzes the three cases of Korean companies in depth, their development process and the assessment of business intelligence, based on the theoretical model on the key success factors of business intelligence systems. The comparative analysis of the three cases including project managers' interviews and performance evaluations provide rich implications for the successful adoption and the use of business intelligence systems of firms. The study is expected to provide useful references for firms to fully leverage the effects of business intelligence systems and upgrade towards self-service business intelligence systems.

• Journal of Environmental Health Sciences
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• v.50 no.1
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• pp.54-65
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• 2024

Background: There is growing international recognition of the need for improvements to national chemical management systems for hazardous chemicals. The European Union has recently introduced the concept of 'essential uses' as a new approach to the management hazardous chemicals by limiting their uses. Objectives: This paper examines the concept of essential uses in chemical management and how to apply it through a case study of essential use. This approach is distinct from the current chemical management system, but seeks to improve its potential benefits by effectively restricting or gradually decreasing the use of hazardous substances. Methods: The concept of essential uses was introduced by reviewing the Montreal Protocol on Substances that Deplete the Ozone Layer, Cousins's three essentiality categories applied to PFAS, restriction options assessed in the PFAS restriction proposal under REACH, and the California Safer Consumer Products regulations prioritizing 6PPD in motor vehicle tires. Based on these essential uses concepts for PFAS and 6PPD, uses of benzene were classified in accordance with the essential uses approach for products using benzene in South Korea. Results: The essential use concept is able to manage the restriction and authorization of substances of concern through essential uses and non-essential uses and the feasible substitution of uses and substances. Conclusions: If the concept and methodology of essential uses are clearly established, they can be expected to shift the national chemical management paradigm from regulating substances to limiting uses under the existing substance management system.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.59-64
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• 2024

In this study, we conducted research on a miniaturized transmission system suitable for ultra-compact electric vehicles, such as electric arts or small electric cars. While conventional electric vehicles eliminate multi-gear transmissions and control motor output or secure initial driving force through reducers, in vehicles like electric karts or compact electric cars, which have relatively small battery capacities, the driving range can be reduced or the motor can be stressed epending on the loading state. Therefore, in this study, we developed a low stage ratio 0.625 and high stage ratio 1.6 a two-stage transmission system that can change gears as needed, considering factors such as slope conditions and loading status, by applying the continuously variable transmission (CVT) mechanism. Based on the selected gear ratios, we designed the transmission and created a test rig to verify the power transmission efficiency of the developed transmission. Using the test rig, we varied the rotational speed and load of the transmission to confirm its power transmission characteristics and also examined the heat generation characteristics during shifting and operation. As a result, developed a two-stage transmission with a CVT structure.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.4
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• pp.615-627
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• 2024

With the evolution of power systems and advancements in IT technology, there is an increasing demand to shift from serial-based communication to TCP/IP-based communication. However, TCP/IP communication entails various security threats, necessitating extensive consideration from an information security perspective. Security measures such as authentication and encryption cannot be rapidly implemented due to issues like the replacement of Remote Terminal Units (RTUs) and the performance requirements of encryption algorithms. This paper proposes a state estimation-based intrusion detection model to identify and effectively detect threats to power control systems in such a context. The proposed model, in addition to signature detection methods, verifies the validity of acquired data, enabling it to detect attacks that are difficult to identify using traditional methods, such as data tampering.

• Journal of the Korean Arthroscopy Society
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• v.12 no.2
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• pp.112-117
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• 2008

Purpose: Double-bundle reconstruction of anterior cruciate ligament(ACL) has the advantage of restoring the isometry and original function of ACL. The purpose of this study is to evaluate the clinical results following double-bundle reconstruction of ACL using autogenous hamstring grafts through an accessory anteromedial portal. Materials and Methods: From January 2005 to July 2006, sixty patients(52 males, 8 females) underwent double-bundle ACL reconstruction using autogenous hamstring tendons..The mean age was 31.7 years($20{\sim}51$ years). The mean follow up period was 13.4 months($12{\sim}16$ months). We made a horizontal-oblique skin incision just medial to tibial tuberosity and harvested semitendinosus and gracilis tendon. Tibial tunnel for posterolateral bundle was made near its anatomical position. By modifying an anatomic reconstruction of ACL by Yasuda et al., we made a femoral tunnel for posterolateral bundle through accessory anteromedial portal. Tunnels for anteromedial bundle were made with conventional method. We reconstructed anteromedial bundle with semitendinosus tendon and posterolateral bundle with gracilis tendon. Clinical results at last follow up were evaluated by range of motion, extent of anterior displacement(KT-1000 arthrometer), pivot-shift test. Functional evaluation of clinical outcomes were evaluated by Lysholm score and modified Feagin Scoring System. Results: There was no limitation of motion of knee joint at last follow up. Mean side to side difference of anterior displacement of tibia by KT-1000 arthrometer was improved from 8.4 mm preoperatively to 1.7 mm postoperatively(p<0.05). Average Lysholm score was improved from 64.1 preoperatively to 92.2 postoperatively(p<0.05). In modified Feagin Scoring System, 90% of cases were rated as good or excellent. Conclusion: Double-bundle reconstruction of ACL using autogenous hamstring grafts through accessory anteromedial portal results in good clinical outcomes.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.139-146
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• 2004

A 2D/3D complex optical system and its vision inspection algerian is proposed and implemented as a single probe system for high speed, precise vision inspection of the solder pastes. One pass un length labeling algorithm is proposed instead of the conventional two pass labeling algorithm for fast extraction of the 2D shape of the solder paste image from the recent line-scan camera as well as the conventional area-scan camera, and the optical probe path generation is also proposed for the efficient 2D/3D inspection. The Moire interferometry-based phase shift algerian and its optical system implementation is introduced, instead of the conventional laser slit-beam method, for the high precision 3D vision inspection. All of the time-critical algorithms are MMX SIMD parallel-coded for further speedup. The proposed system is implemented for simultaneous 2D/3D inspection of 10mm${\times}$10mm FOV with resolutions of 10 ${\mu}{\textrm}{m}$ for both x, y axis and 1 ${\mu}{\textrm}{m}$ for z axis. Experiments conducted on several nBs show that the 2D/3D inspection of an FOV, excluding an image capturing, results in high speed of about 0.011sec/0.01sec, respectively, after image capturing, with $\pm$1${\mu}{\textrm}{m}$ height accuracy.

• Archives of design research
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• v.13 no.3
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• pp.281-292
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• 2000

Today, the rapid economic growth and emerging new trends have been changed radically throughout the society and they especially have affected the changes of life-style and the diversity of residents'demands in housing life. This changes of life have brought the shift in family form from traditional type, thus new phase of nuclear family means that it makes on the whole, variable family forms such as single family, non-blood one, a generation one and so on. It therefore is time that we should not only explore current housing plans, but envisage concept of new living space to satisfy latent need of the occupants. But the forms, in spite of the diversity of user's needs and the change of life-style, of many houses as many apartment and tenement houses supplied so far have been clearly limted, and housing policy of the mass-supply causes monotonous space composition, over-occupation and non-changeability. Now, the collective houses have some limits owing to the commoness and assemblage, but they have failed to keep up with the variable and changeable life-style of residents. These problems, to put it concretely, lead to increasing needs for the number of rooms in proportion to family members, for the change of behavior using the space. We therefore need to propose the new living space. As the current plans for designing house are based on the average life-style of people, they can not cope with variable demands of the resident. For that reason, this paper will propose the manual space system as an alternative for it and the goal is to suggest new furniture system which we need to create the flexibility of living space.

• Journal of Engineering Education Research
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• v.2 no.1
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• pp.39-50
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• 1999

In recent globalization era, Korean architectural education and profession are emerging as the fields with serious problems. There are two major reasons. One is an internal factor caused by Ministry of Education's full scale shift from department to faculty system. Due to the drastic change in this system, most of schools have serious difficulties to deliver the proper professional education. And the other is an external factor. In WTO era, Union of International Architects has adopted $\ulcorner$UIA Accord on Recommended International Standards of Professionalism In Architectural Practice$\lrcorner$. According to the education section of the Accord, it requires 5 years of professional education in the accredited school. So, if it is formally adopted in the Beijing Congress, which is scheduled to be held in June 1999, we may face very serious problems in architectural education. As mentioned above, with the present education system it is believed not easy to meet their new criteria. Within the present system, which does not have any mandatory relationship with professional licence, students might go on to diverse fields such as architectural design, structural engineering, construction management and building equipment engineering. However, if UIA Accord and Engineering Accreditation are required at the same time, it will not be easy to meet their new criteria with present architectural education system. The goal of this paper is to suggest the models to meet the standards of international community while keeping the strengths of existing systems.