• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.90-95
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• 1997

In this work, linear dynamics of a circulating fluid-fueled subcritical reactor system with temperature feedback and external neutron source was modeled and examined. In a circulating fluid-fuel system, the stable region is slightly moved by a circulation fluid effect. The effects of subcriticality and temperature feedback coefficient on the reactor stability were tested by calculating frequency response of neutron density originated from reactivity perturbation or external source oscillation of system. The amplitude transfer function has a different shape near subcritical region due to the exponential term in the transfer function. The results of the study show that at a slightly subcritical region, low frequency oscillation in accelerator current or reactivity can be amplified depending on the temperature feedback. However, as the subcriticality increases, the oscillation becomes negligible regardless of the magnitude of the temperature feedback coefficient.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.389-392
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• 2000

This paper presents a performance Analysis of electrically exhaust gas recirculation valve using commercial electromagnetic simulation software, Flux2D. Under the assumption of 2D axi-symmetric magnetic field, the characteristics of EEGR valve by revising the design parameter, has ken investigated by estimating the variation of thrust force with respect to the pintle position. The mode shapes and the frequency response functions were computed by using three dimensional finite element modeling of the whole EEGR valve and their accuracies were verified with experimental FFT analysis technique.

• Ocean and Polar Research
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• v.38 no.4
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• pp.325-330
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• 2016

Partial high frequency bands were allocated to the operation of ocean surface radars that monitor the sea surface currents and waves in WRC-12. On that basis, government-related organizations revised the table of domestic frequency allocation. In order to study radio environments in the allocated bands for ocean radar, tests of the radio signal spectrum were carried at 7-sites using the receiver of the ocean surface radar system operated with a shutdown of the transmitter for 10-60 min. The results showed that no serious radio noises occur at 25 and 43 MHz bands, indicating a good radio environment for the ocean surface radar operation. However, at 13 MHz band, it was difficult to generate stable and confidential data from the ocean surface radar because serious radio noises occurred continuously.

• Journal of the Korean housing association
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• v.17 no.2
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• pp.143-150
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• 2006

In this Study, it was investigated what the critical elements of the Architectural Review by the Seoul Building Design Committee were. The critical elements selected by the members of committee were systematically analyzed. They were based on the 169 cases reviewed by the Building Design Committee. The committee consists of Professors, famous architects, architectural experts and official members. Thus, the critical elements selected by the committee can be regarded as the important criteria for the forthcoming architectural reviewing process. The critical elements selected by 960 members of the committee were classified by the frequency. The results in this study showed that the critical elements were ordered as follows: (1)floor plan, (2)landscape gardening, (3)form, (4)open space, (5)structure, (6)plan for preventing disasters, (7)circulation for men and cars, (8)facilities, (9)parking, (10)revision of drawings and documents. These criteria of the architectural evaluation established by the Seoul Building Design Committee can be applied to the fundamental preparation of the architectural review.

• Journal of Power Electronics
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• v.13 no.3
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• pp.458-468
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• 2013

Large capacity reactive power compensation and harmonic control in the low-voltage grid of an enterprise, are important technical means to improve power quality and reduce power loss. In this paper, the principle of an efficient power quality controller is analyzed. Then, key application technologies of the HPQC which would influence the performances of the HPQC are studied. Based on an analysis of the harmonic shunt problem, a frequency dividing control strategy of the HPQC continuous subsystem is proposed. A parameter design method of the HPQC discrete subsystem and its installation method are also proposed to ensure the system compensation effect. HPQC systems have been designed for a copper foil plant. The effectiveness of this paper has been verified by the simulation and application results.

• The Journal of the Korea Contents Association
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• v.16 no.9
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• pp.198-210
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• 2016

The purpose of this study is to analyze the tourists' circulations and behaviors at one of the representative dark tourism sites in Seoul, named Seodaemun Prison History Hall. This study conducts direct observation and behaviour tracking or follow-up survey based on traffic circulation and visitors' Muse-Ethogram extracted from the previous studies. The result of tourists' actual circulations shows that main tourists' flows of study areas consist of 3 approaches; suggested, unstructured and directed approaches. And tourists' behaviors such as moving(M), stop looking(SL), and reading(RE) reveal with the highest frequency. This study finds the 'expressing feeling(EXP)' as a new visitor' behavior in dark tourism site. The highest frequency of visitors' movement patterns is stop looking-reading-move(SL-RE-M). The results of this study could be used as a planning and design guidelines of dark tourism related to exhibition circulation, visitors' behaviors and development of exhibition content.

• Journal of Chest Surgery
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• v.7 no.1
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• pp.109-116
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• 1974

Eleven cases of peripheral arterial injuries treated at Korea University Woo Sok Hospital during these 3 years and 3 months from Feb. 1971Eleven cases of peripheral arterial injuries treated at Korea University Woo Sok Hospital during these 3 years and 3 months from Feb. 1971 to May 1974 were reviewed. Common causes of injuries were stab wound, automobile accidents and iatrogenic injuries during operation. Of the 11 arterial injuries 3 were femoral artery which` was the commonest in frequency and the next was 2 cases of brachial artery. The most frequent type of injury was transection. Laceration, contusion and spasm was also recognized. The need to operate immediately following an injury was emphasized. Operative procedures were end to end anastomosis and saphenous vein graft in 5 and 2 cases, respectively. Other cases were undergone multiple suture ligature due to staphyllococcal infection, insertion of polyethylene catheter, and lateral suture after thromboendarterectomy. Fractures and extensive soft tissue damage associated with arterial injuries with widespread destruction of the collateral circulation aggravated the situation and complicated the amputation of lower extremity in 4 cases. The factors influencing the amputation were time lag, presence of associated injuries and complications.[KTCS 1974;1:109-116] Common causes of injuries were stab wound, automobile accidents and iatrogenic injuries during operation. Of the 11 arterial injuries 3 were femoral artery which` was the commonest in frequency and the next was 2 cases of brachial artery. The most frequent type of injury was transection. Laceration, contusion and spasm was also recognized. The need to operate immediately following an injury was emphasized. Operative procedures were end to end anastomosis and saphenous vein graft in 5 and 2 cases, respectively. Other cases were undergone multiple suture ligature due to staphyllococcal infection, insertion of polyethylene catheter, and lateral suture after thromboendarterectomy. Fractures and extensive soft tissue damage associated with arterial injuries with widespread destruction of the collateral circulation aggravated the situation and complicated the amputation of lower extremity in 4 cases. The factors influencing the amputation were time lag, presence of associated injuries and complications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.10-17
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• 2007

Numerical results from the "figure-of-eight" motion of Phormia-Regina in Part 1 indicate that vortical structure and vortex dynamics do play a critical role in lift and thrust generation. The aerodynamic force generation of insects' wing could be governed by aerodynamic parameters such as Reynolds number; kinematic parameters such as frequency, amplitude, and component of the figure of eight motion; and morphological parameters such as wing shape and the number of wing. In the present work, the effects of Reynolds number, reduced frequency and motion component are investigated in detail to clarify aerodynamic characteristics of insect wing. Through numerical results and their physical interpretation, the mechanism of aerodynamic force generation is presented more clearly. Rotation turns out to be the most important component in thrust generation and subsequent counterclockwise rotational circulation is closely related with thrust generation.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.11 no.1
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• pp.162-179
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• 1998

In the literatual studies on the yupung(油風), the results were as follows. 1. Yupung(油風) was called 'Quijidu(鬼지頭)', 'Quichedu(鬼剃頭)', 'Ballak(髮落)' etc. It was a localized loss of hair in round or oval ares without any subjective symptom 2. The etiology and pathogenesis of Yupung were disorder of vital energy& blood circulation caused by deficiency of blood and wind-dryness syndrome, energy-stagnation and blood stasis, impairment of the liver & kidney. The treatments of Yupung were invigorating the liver & kidney, clearing away heat-evil and cooling blood, nourishing the liver & kidney, activating blood circulation to dissipate blood stasis etc, 3. In the frequency of prescription, the most numerous prescription is Shineuingyangjindan(神應養眞丹) and the next are Tonggyuhwalhyultang(通竅活血湯) & Chilbomiyumdan(七寶美髥丹), 4. In the frequency of medicine, the most numerous medicine is Radix Angelicae Sinensis(當歸) and the next are Rhizoma Rehmanniae Praeparatae(熟地黃) & Rhizoma Ligusiici Chuanxiong(川芎). 5. In classification of drug action, medicines of clearing away wind-heat evil and invigorating yin used to be very busy. 6. In classification of four characters, the most parts are warm medicine. 7. In classification of five tastes, the most numerous tastes are sweet and bitter tastes. 8. In classification of toxicity, the most is non-toxic medicines. 9. In classification of the channel distribution, the most is the medicine that belongs to liver channel. 10. In acupuncture theraphy, it was used 'GV20(百會)', 'G20(風池)', 'GV16(風府)', 'GV14(大椎)', 'LI4(合谷)' etc. in body acupuncture, was used 'S25(天樞)', 'GV14(大椎)', 'B13(肺兪)', 'LI11(曲池)' etc. in moxibustion.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.141-154
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• 2023

This study investigated the effect of water retention characteristics between aged and fresh Municipal Solid Waste (MSW) on the stability of the landfill. A series of transient numerical modeling for the slope of an MSW landfill was performed considering the variation of water retention characteristics due to leachate circulation. Four different scenarios were considered in this analysis depending on how to obtain hydraulic conductivity and the aging degree of materials. Unsaturated hydraulic properties of the MSW used for the modeling were evaluated through modified hanging column tests. Different water retention properties and various landfill conditions, such as subgrade stiffness, leachate injection frequency, and gas and leachate collection system, were considered to investigate the pore water distribution and slope stability. The stability analyses related to the factor of safety showed that unsaturated properties under those varied conditions significantly impacted the slope stability, where the factor of safety decreased, ranging between 9.4 and 22%. The aged materials resulted in a higher factor of safety than fresh materials; however, after 1000 days, the factor of safety decreased by around 10.6% due to pore pressure buildup. The analysis results indicated that using fresh materials yielded higher factor of safety values. The landfill subgrade was found to have a significant impact on the factor of safety, which resulted in an average of 34% lower factor of safety in soft subgrades. The results also revealed that a failed leachate collection system (e.g., clogging) could result in landfill failure (factor of safety < 1) after around 298 days, while the leachate recirculation frequency has no critical impact on stability. In addition, the accumulation of gas pressure within the waste body resulted in factor of safety reductions as high as 24%. It is essential to consider factors related to the unsaturated hydraulic properties in designing a landfill to prevent landfill instability.