• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.463-470
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• 2006

This paper deals with a new 3-phase power quality disturbance generator. The proposed generator can provide phase jump as well as voltage sag, swell, outage, unbalance, and over and under voltage. The operating principle of the generator is described in each mode of disturbance. The magnitude of the phase jump is analysed and it is found that the magnitude is the function of the turn-ratios of the transformers consisting the generator. The scheme has simple structure compared with the conventional one, and the major components of the proposed scheme are SCR thyristor and transformer, which guarantees high reliability and cost-effective implementation of the generator. Furthermore, high efficiency can be obtained because there is no PWM switching of the semiconductor devices, and it is easy to control the system. Simulations are carried out to confirm the operation in each disturbance mode, and experiments has been done with 5kVA power rating. The usefulness of the proposed scheme is verified through simulation and experimental results. It is expected that the scheme can be applied to the performance test of the custom power devices such as UPS, DVR, DSTATCOM, and SSTS with cost-effective system.

• Journal of The Korean Association of Information Education
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• v.19 no.3
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• pp.311-322
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• 2015

This study analyzed the trend and problems in the design of contents developed by teachers, and suggested strategies for improvement. It analyzed the contents ranked as the first level in the Research Competition on Educational Informatization for the last 3 years. Concerning the 8 types of instructional activities and the 6 types of knowledge acquisition, most contents took limited types(i.e., the individual tutoring type, the concept learning type and the principle learning type). In addition, when the contents were evaluated according to the quality certification criteria for educational software, it was found that the quality level of the design was low in many criteria. When the content analysis was applied for the in-depth analysis of design characteristics, various problems were found in the areas such as evaluation, feedback and learning objectives. Also other common problems were found in the design areas such as level-based differentiated learning, interaction between students and contents, presentation of text and narration, utilization of information on a student, screen design, the content level appropriate for students. In relation to the problems found from the analysis, some strategies for improvement were suggested concerning the following topics: question selection and guidance for evaluation, content and types of feedback, statement of learning objectives, selection of content, interaction, and screen design.

• Culinary science and hospitality research
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• v.18 no.1
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• pp.259-271
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• 2012

As the society's expectations of business have drastically amplified in recent years, an increasing number of companies have devoted their resources and managerial attention to corporate social responsibility. However, little information bas been reported on consumers' expectations on social responsibility of restaurant companies. This research studied the consumer's perception on the socially responsible business practices of restaurant companies. The research also investigated if the customer's expectations differ based on the types of restaurants. Overall, it was found that the consumers strongly feel the necessities of restaurants' socially responsible activities and publicity of those activities (4.08 and 4.05, respectively, out of 5). They also responded that the socially responsible behaviors of restaurants somewhat affect their purchase decisions (3.74 out of 5). As a result of a principle component analysis, five types of socially responsible activities(i.e., philanthropic responsibility, economic responsibility, community responsibility, environmental protection responsibility, and consumer protection responsibility) were extracted. In addition, the results showed that the consumer's expectations toward socially responsible activities of restaurants differ based on the types of restaurants (multivariate F=4.616, p=0.000).

• Communications of Mathematical Education
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• v.25 no.2
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• pp.323-339
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• 2011

The expansion of exponential law as the law of calculation of integer numbers can be a good material for the students to experience an extended configuration which is based on an algebraic principle of the performance of equivalent forms. While current textbooks described that exponential law can be expanded from natural number to integer, rational number and real number, most teachers force students to accept intuitively that the exponential law is valid although exponent is expanded into real number. However most teachers overlook explaining the value of exponent of rational number or exponent of irrational number so most students have a lot of questions whether this value is a rational number or a irrational number. Related to students' questions, most teacher said that it is out of the current curriculum and students will learn it after going to college instead of detailed answers. In this paper, we will present several examples and the values about irrational exponents of a positive rational and irrational exponents of a positive irrational number, and study the recognition and fallacy of would-be teachers about the cases of irrational exponents of a positive rational and irrational exponents of a positive irrational number at the expansion of exponential law.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.3
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• pp.41-63
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• 2004

The area covered by product liability in broadest sense is so vast that an attempt to analyse all its impact on the aviation world risk. Every effort has been made to confine our review of subject a closely as possible to its influence on aircraft manufacturers, airlines and passengers, in spite of strong connections with other spheres of commercial. Product Liability in aviation is the liability of aircraft's manufacturer, processor or non-manufacturing seller for injury to the person or property of a buyer or third party caused by a product which has been sold. Here-in a product is aircraft, third party is passengers who suffered damage by defective design, defective construction, inadequate instructions for handling in aircraft. Whenever a product turns out to be defective after it has been sold, there are under Anglo-American law three remedies available against the aircraft's manufacturer (1) liability for negligence (2) breach of warranty (3) strict liability in tort. There are Under continental law Three remedies available against the aircraft's manufacturer (1) liability for defective warranty (2) liability for non-fulfillment of obligation (3) liability in tort. It is worth pointing out here an action for breach of warranty or for defective warranty, for non-fulfillment of obligation is available only to direct purchaser on the basis of his contract with the aircraft's manufacturer, which of course weakness its range and effectiveness. An action for tort offers the advantage of being available also to third parties who have acquired the defective product at a later stage. In tort, obligations are constituted not only by contract, but also by stature and common law. In conclusion, There in no difference in principle of law. In conclusion I would like to make few suggestions regarding the product liability for aircraft's manufacturer. Firstly, current general product liability code does not specify whether government offices(e.g. FAA) inspector conducted the inspection and auditory certificate can qualify as conclusive legal evidence. These need to be clarified. Secondly, because Korea is gaining potential of becoming aircraft's manufacturer through co-manufacturing and subcontracting-manufacturing with the US and independent production, there needs legislation that can harmonize the protection of both aircraft's manufacturers and their injured parties. Since Korea is in primary stage of aviation industry, considerate policy cannot be overlooked for its protection and promotion. Thirdly, because aircraft manufacturers are risking restitution like air-carriers whose scope of restitution have widened to strict and unlimited liability, there needs importation of mandatory liability insurance and national warranty into the product liability for aircraft's manufacturers. Fourthly, there needs domestic legislation of air transportation law that clearly regulates overall legal relationship in air transportation such as carrier & aircraft manufacturer's liability, and aviation insurance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.301-317
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• 2002

Recently, a geophysical exploration technology is frequently utilized in the civil engineering field as well as in the resource exploration. It might be important for civil engineers to understand the fundamental theory of seismic survey and limitation of the technique when utilizing these techniques in the civil engineering field. A 3-dimensional migration technique based on the principle of ellipsoid to predict the fractured zone ahead of tunnel face utilizing the tunnel seismic survey was proposed so that the geometry of the fractured zone can be estimated, i.e. the angle between tunnel axis and discontinuity zone, and the dip. Moreover, a numerical analysis technique to simulate the TSP (Tunnel Seismic Prediction) test was proposed in this paper. Based on parametric studies, the best element size, the analysis time step, and the dynamic characteristics of pressure source were suggested to guarantee the stability and accuracy of numerical solution. Example problems on a hypothetical site showed the possibility that the 3-dimensional migration technique proposed in this paper appropriately estimate the 3D-geometry of fractures ahead of tunnel face.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.7
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• pp.387-394
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• 2016

Commercial 28 algae removal technologies that have been applied in domestic rivers and lakes with green tide were investigated, analyzed and classified. The classification of algae removal technologies was based on the three criteria (i.e., principle, flow rate of water body, and application period). Also, algae removal technologies were evaluated in terms of cost effectiveness, field applicability, effect durability, and eco friendliness. From the analysis results, technologies using physical, chemical, biological, and convergent controls were 32.2%, 25%, 21.4%, and 21.4%, respectively. The 75% of technologies have been applied to stagnant water body (${\leq}0.2m/s$). Also, algae harvesting ship with dissolved air flotation, conveyor belt and filtration processes and natural floating coagulant were found to have better field applicability, compared to other technologies. However, proper algae removal technology in specific rivers and lakes should be chosen after the evaluation of long-term pilot scale field test. Also, development of energy and resource recovery technologies from algae biomass is warranted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.144-153
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• 2016

This study examined the recent study trends through a systematic review of the effect of sensory integration intervention and the objective reason to show the areas where sensory integration intervention is effective. The databases, Medline and EMBASE, were searched for "Occupational therapy", "Sensory integration therapy", "Sensory processing", "Weighted vest", and "Wilbarger protocol". For the analysis studies, 14 studies on the effects of sensory integration intervention from 2010 to 2015 were analyzed and organized according to the principle of PICO. According to the result, there were 4 studies each of evidence levels I and e V, which was the largest number of studies (28.6%). The result from frequency analysis of the measurement used for measuring the effects of intervention showed that GAS and VABS-II were used in the 4 studies (11.8%). 71.4% of children with autism spectrum were the major subject group in the analysis studies and sensory integration intervention had an effect on the motor performance, sensory processing, behavior, learning-related education, and occupation performance area. This study result will be useful for establishing sensory integration as an interventional program in occupational therapy practice. In further studies, it will be important to verify the intervention effect of sensory integration in another rehabilitation area.

• Food Science of Animal Resources
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• v.20 no.4
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• pp.303-310
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• 2000

In vitro 소화시 계란 성분이 anti-Y ruckeri IgY 항세 활성을 안정화시키는데 어떡해 관여하는지를 SDS-PAGE와 ELISA로 조사한 결과는 다음과 같다. Anti-Y ruckeris IgY 항체와 난황 및 난백으로 혼합 후 펩신으로소화시킨 후 경우 1시간 후 난황 및 난백이 혼합된 시료에서 모두 anti-Y ruckeri IgY 항체의 heavy chain과 light chain이 분해는 되었지만 어느 정도 밴드를 관찰할 수있었으며, anti-Y, ruckeri IgY 항체 활성 측정한 결과 난황시료는 35%, 난백시료는 61%의 항체 활성을 유지시켰다. Anti-Y ruckeri IgY 항체와 오보알부민, 오보뮤우신, 라이소자임 및 오보뮤코이드를 혼합 한 후 펩신으로 소화시킨 경우 1시간 우에는 anti-Y, ruckeri IgY항체의 heavy chain의 밴드르 fdjsm 정도 볼 수 있는 형태로 나타났으며, anti-Y, ruckeri IgY 항체의 light chain는 오보뮤우신 및 오보뮤코이드가 홉합되어 펩신으로 소화시킨 경우 1시간 후에는 밴드를 거의 볼수 없었으나 오보알부민 오보트란스훼린 및 라이소자임에 혼합된 시료에서 밴드를 관찰할수 있었다. 특히 라이소자임과 오보트란스훼린의 경우 펩신 호화 2시간 우에도 anti-Y, ruckeri IgY 항체의 light 밴드가 관찰되었다. 펩신소화 1시간 후에 난백성분이오보알부민, 오보뮤우신, 라이소자임, 오보트란스웨린 및 오부뮤코이드 중에서 단지 오보트란스훼린만이 38%의 anti-Y, ruckeri IgY 항체 활서을 보인후 2시간 후에도 15% 정동의 활성을 나타내었다. anti-Y, ruckeri IgY항체와 난백 및 전란을 혼합한 다음 무지개송어 위 추출액으로 소화시 2시간 후에 난백은 14%, 전란은 69%로 anti-Y, ruckeri IgY 항체 활성을 유지시킨 것으로 나타났다.X> $e_{I}$ WPi_BE_QE]]]]]로 상징하며 WLWQ에 적용되는 몇 가지 제약을 관찰하고 이를 일반적인 언어원리로 설명한다. 첫째, XP는 주어로만 해석되는데 그 이유는 XP가 목적어 혹은 부가어 등 다른 기능을 할 경우 생략 부위가 생략의 복원 가능선 원리 (the deletion-up-to recoverability principle)를 위배하기 때문이다. 둘째, WLWQ가 내용 의문문으로만 해석되는데 그 이유는 양의 공리(the maxim of quantity: Grice 1975) 때문이다. 평서문으로 해석될 경우 WP에 들어갈 부분이 XP의 자질의 부분집합에 불과하므로 명제가 아무런 정보제공을 하지 못한다. 반면 의문문 자체는 정보제공을 추구하지 않으므로 앞에서 언급한 양의 공리로부터 자유롭다. 셋째, WLWQ의 XP는 주제어 표지 ‘는/-은’을 취하나 주어표지 ‘가/-이’는 취하지 못한다(XP-는/-은 vs. XP-가/-이). 이는 IP내부 에 비공범주의 존재 여부에 따라 C의 음운형태(PF)가 시성이 정해진다는 가설로 설명하고자 했다. WLWQ에 대한 우리의 논의가 옳다면, 본 논문은 다음과 같은 이론적 함의를 기닌다. 첫째, WLWQ의 존재는 생략에 대한 두 이론 즉 LF 복사 이론과 PF 삭제 이론 중 전자의 입장을 지지한다. 둘째, WP를 XP로부터 복원할 때 부분 자질만 복사된다. 이는 어휘가 통사층위로 들어온 이후에도 어휘 자질들이 완전히 동결되는 것이 아니라 계속 지시될 수 있다는 가설을 지지한다.