• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1711-1715
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• 2006

최근 급격한 도시화는 홍수량 증가 및 갈수 시 하천의 건천화 등 유역의 유출특성 변화를 가져왔다. 본 연구에서는 이러한 문제를 해결하는 방안 중 하나인 투수성 포장의 유역 내 수문학적 효과를 분석하였다. 이를 위해 투수성 포장을 이용한 수리모형 실험 및 수치모형(SWMM)을 병행하여 수행하였다. 연구에 사용한 수치모형은 기존 도시유출 모형인 SWMM(Storm Water Management Model) 모형에 투수성 포장의 수문학적 효과를 고려할 수 있도록 수정된 모형이며, 수리모형 실험 결과를 토대로 수치모형의 중요 매개변수를 추정하였다. 또한 실험에 의해 관측된 지표 및 지하수 유출량과 수치모형에 의해 산출된 자료를 비교.분석하여 수정된 SWMM 모형의 유용성을 평가하였다. 강우강도가 65 mm/hr, 90 mm/hr, 95 mm/hr인 강우를 4시간씩 공급하는 경우에 대한 3가지 수리모형 실험을 수행하였다. 수리모형실험 결과 강우강도는 지표면 유출의 크기에 직접적인 영향을 미치고 있었으며 지하수 유출량은 강우강도 보다는 지하수위 조건에 더 큰 영향을 받는 것으로 분석되었다. 수리모형 실험결과 및 수치모형 모의결과를 비교 분석한 결과, 토양 함수량 및 지하수위 변동 특성은 초기에서 정상상태로 전이되는 부분과 강우 정지 후 감소되는 부분에서 수리모형 실험과 다른 양상을 보였다. 지하수위는 실험 시 발생하는 공기층의 포집이 많은 영향을 미치고 있음을 알 수 있었고, 함수량 변화에 있어서는 수치모형(SWMM)의 모의 결과가 과도하게 감소하는 특성을 보여 주고 있었다. 즉, 유출량의 특성은 비슷한 양상을 보이고 있으나 지하수위 변화 및 토양 내 함수량 변화 예측에 있어서는 그 정확도가 떨어지는 것으로 평가되었다. 그러나 본 연구결과를 통하여 투수성 포장과 지하수에 관련된 매개변수의 집적과 분석결과는 현장기술 적용 시 매개변수의 유용한 선택과 도시유역의 물 순환 건전화 대안기술 적용에 효과적인 방법론을 제시할 수 있을 것으로 사료된다.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.755-765
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• 2012

The Land Surface Temperature (LST) is one of the significant factors to understand the water and energy cycles between the land surface and atmosphere. However, few previous studies for spatio-temporal variations of LST has been investigated. In this study, we conducted comparative analyses between the Communication, Ocean and Meteorological Satellite (COMS) and MOderate-Resolution Imaging Spectroradiometer (MODIS) LST data. We compared COMS data with observations to identify the accuracy and found relative underestimated patterns of the COMS data as compared to observations. We also found that COMS LST were underestimated in compare to MODIS LST. The Terra LST was verified to have more similar trends with the COMS LST rather than Aqua LST. While we identified the applicability of COMS based on the results of similar tendencies of two comparisons, more intensive validation research at a variety of field conditions should be conducted to gurantee current COMS LST.

• Korean Journal of Logic
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• v.5 no.2
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• pp.39-66
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• 2002

일반적으로 엄밀한 방법을 통하여 증명되었다고 말해지는 괴델의 불완전성 정리는 일련의 전제와 배경지식이 요구된다고 하겠다. 이들 중에서 무엇보다도 중요한 것은 정리의 증명에 사용되는 메타언어상의 수학적 참에 대한 개념이다. 일단 확인할 수 있는 것은 "증명도, 반증도 되지 않지만 참인 산수문장의 존재"라는 불완전성 정리의 내용에서 괴델이 가정하고 있는 수학적 참의 개념이 구문론적인 증명개념으로부터 완전히 독립되어야 한다는 점이다. 문제는 그가 가정하고 있는 수학적 참의 개념이 도대체 무엇이어야만 하겠는가라는 점이다. 이 논문은 이 질문과 관련하여 내용적으로 3부분으로 나누어 질 수 있다. I. 괴델의 정리의 증명에 필요한 전제들 및 표의 도움을 얻어 자세히 제시되는 증명과정의 개략도를 통해 문제의 지형도를 조감하였다. II, III. 비트겐슈타인의 괴델비판을 중심으로, "일련의 글자꼴이 산수문장이다"라는 주장의 의미에 대한 상식적 비판 및 해석에 바탕을 둔 모형이론에 대한 대안제시를 통하여 괴델의 정리를 증명하기 위해 필요한 산수적 참에 관한 전제가 결코 "확보된 것이 아니다"라는 점을 밝혔다. IV. 괴델의 정리에 대한 앞의 비판이 초수학적 전제에 대한 것이라면, 3번째 부분에서는 공리체계에서 생성 가능한 표현의 증명여부와 관련된 쌍조건문이 그 도입에 필수적인 괴델화가 갖는 임의성으로 인해 양쪽의 문장의 참, 거짓 여부가 서로 독립적으로 판단 가능하여야만 한다는 점에(외재적 관계!) 착안하여 궁극적으로 자기 자신의 증명여부를 판단하게 되는 한계상황에 도달할 경우(대각화와 관련된 표 참조) 그 독립성이 상실됨으로 인해 사실상 기능이 정지되어야만 한다는 점, 그럼에도 불구하고 이 한계상황을 간파할 경우(내재적 관계로 바뀜!)항상 순환논법을 피할 수 없다는 점을 밝혔다. 비유적으로 거울이 모든 것을 비출 수 있어도 자기 스스로를 비출 수 없다는 점과 같으며, 공리체계 내 표현의 증명여부를 그 체계내의 표현으로 판별하는 괴델의 거울 역시 스스로를 비출 수는 없다는 점을 밝혔다. 따라서 괴델문장이 산수문장에 속한다는 믿음은, 그 문장의 증명, 반증 여부도 아니고 또 그 문장의 사용에서 오는 것도 아니고, 플라톤적 수의 세계에 대한 그 어떤 직관에서 나오는 것도 아니다. 사실상 구문론적 측면을 제외하고는 그 어떤 것으로부터도 괴델문장이 산수문장이라는 근거는 없다. 그럼에도 불구하고 괴델문장을 산수문장으로 볼 경우(괴델의 정리의 증명과정이라는 마술을 통해!), 그것은 확보된 구성요소로부터 조합된 문장이 아니라 전체가 서로 분리불가능한 하나의 그림이라고 보아야한다. 이것은 비트겐슈타인이 공리를 그림이라고 본 것과 완전히 일치하는 맥락이다. 바론 그런 점에서 괴델문장은 새로운 공리로 도입된 것과 사실은 다름이 없다.

• Fashion & Textile Research Journal
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• v.19 no.5
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• pp.646-652
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• 2017

In order to clarify an availability of water treatment for persimmon extract dyeing, effect of color developing by water treatment process on cotton fabrics dyed with persimmon extract was investigated. Dyed fabrics were dipped still water and circulation water in various temperature. Concerning water color developing, still water color developing and circulation water color developing have been examined, and the temperature of water has been apprehended to prepare an effective basis of water color development. The surface color based on circulation water color development displays low values of $a^{\ast}$ and $b^{\ast}$, and the range of the c value(Munsell chroma) is narrow and has the value of 2 to 3, thus displays the coloration of a dark tone. The effect of temperature in water color development was insignificant, due to the small difference in temperature from $20^{\circ}C$ to $40^{\circ}C$. At $80^{\circ}C$, remarkable color development manifested, which is evidence of the high influence of temperature. The effects of circulation were clear at low temperatures, and the effects of temperature highly manifested at high temperatures. Circulation water color development display great color development at all temperatures to allow industrial color development with the absence of sunlight, thereby having an effect of energy reduction and developing color in dark tones, however this also is a strength of persimmon extract concerning color diversification, and is judged to have great value of industrial and practical application.

• Journal of Chest Surgery
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• v.31 no.2
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• pp.113-117
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• 1998

From October 1993 to April 1997, 37 patients(30 male and 7 female patients), ranging in age from 23 to 73 years, were operated for annuloaortic ectasia with or without aortic dissection. Four patients were in New York Heart Association Class I, 10 in Class II, 20 in Class III, and 3 in Class IV. In cases of annuloaortic ectasia with aortic dissection, the surgical treatment in all cases consisted of total replacement of the ascending aorta with composite graft and reimplantation of the coronary arteries to the tube graft. The postoperative complication, as postoperative bleeding or LV dysfunction, was 18%(7 cases) and late mortality for entire group was 2.7%(one death). The period of follow-up ranged from 1 month to 36 months(average 9.6 months). In conclusion, Bentall operation for annuloaortic ectasia with or without aortic dissection is reliable method with low mortality and excellent short-term results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.359-367
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• 2018

The vortex ring state that occurs during the descending flight of a rotorcraft generates a circulating flow like a donut near the rotating surface, and it often causes a rotorcraft fall due to loss of thrust. In this paper, we have physically identified the flow field in the vortex ring state of the quadcopter, one of the types of unmanned aerial vehicles. The descending flight of the quadcopter was simulated in a 1m subsonic wind tunnel of the Korea Aerospace Research Institute(KARI) and the Particle Image Velocimetry(PIV) was used for the flow field measurement. The induced velocity in the hovering state is estimated by using the momentum theory and the test was carried out in the range of descent rate at which the vortex ring condition could be caused. The development and the direction of the vortex ring were confirmed by the measurement of the flow field according to not only the descent rate but also propeller separation distance. In addition, the results of the study show the vortex ring state can be predicted sufficiently by measuring the flow velocity around the quadcopter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.610-616
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• 2020

This study conducted joint research with the Navy logistics command ship technology research institute to resolve the occurrence of naval vessel's high-temperature warning and equipment shutdown caused by VRTU overheating during summer operation and the dispatch of troops to equatorial regions. The cooling effect was checked according to the installation of a thermoelectric device cooling system, and heat flow and heat transfer characteristics inside VRTU was analyzed using Computational Fluid Dynamics. In addition, the temperature distribution inside the engine room was assessed through interpretation, and the optimal installation location to prevent VRTU overheating was identified. As a result, the average volume temperature inside the VRTU decreased by approximately 10 ℃ with the installation of the cooling system, and the fan installed in the cooling system made the heat circulation smooth, enhancing the cooling effect. The inside of the engine room showed a high-temperature distribution at the top of the engine room, and the end of the HVAC duct diffuser showed the lowest temperature distribution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.165-172
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• 2017

In this study, centrifugal fan blades used to circulate cold air inside a household refrigerator were optimized to achieve high performance and low noise by using the response surface method, which is frequently employed as an optimization algorithm when multiple independent variables affect one dependent variable. The inlet and outlet blade angles, and the inner radius, were selected as the independent variables. First, the fan blades were optimized to achieve the maximum volume flow rate. Based on this result, a prototype fan blade was manufactured using a 3-D printer. The measured P-Q curves confirmed the increased volume flow rate of the proposed fan. Then, the rotation speed of the new fan was decreased to match the P-Q curve of the existing fan. It was found that a noise reduction of 1.7 dBA could be achieved using the new fan at the same volume flow rate.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.103-108
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• 2004

The space environment is characterized such a severe condition as high vacuum and very low temperature. Since a satellite will be exposed such a space environment as soon as it goes into the its orbit, thermal vacuum test should be carried out to verify the performance of the satellite on the ground under the space environmental conditions. KARI has a thermal vacuum chamber with useful dimensions of ∮3.6m×L3m, in which KOMPSAT-1 and KOMPSAT-2 satellites were tested. But very large thermal vacuum chamber with useful dimensions of ∮8m×L10m has been needed to meet the future demand of large satellites. Generally, the thermal vacuum chamber can be divided into a vacuum system and a thermal system. Especially, a cryogenic system in the thermal system simulates very low temperature of -196℃ under the high vacuum condition. In this paper, we propose the new cryogenic system can be applied to the future large thermal vacuum chamber.

• The Korean Journal of Emergency Medical Services
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• v.21 no.2
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• pp.51-61
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• 2017

Purpose: This study measured return of spontaneous circulation (ROSC) in relation to dispatch distance in patients with out-of-hospital cardiac arrest. Methods: Of 2,347 out-of-hospital cardiac arrest patients transported by emergency medical technicians in J Province between January 1 and December 31, 2015, those under age 18, those with reserved resuscitation, and those with traumatic cardiac arrest, leaving 855 patients in the study sample. ROSC was compared between those with dispatch distance ${\leq}4km$ (short dispatch distance, 465 patients) and those with dispatch distance >4 km (long dispatch distance, 390 patients). Results: The mean was 2.17 km in the short dispatch group and 9.87 km in the long dispatch group (p=.000). Mean distance from was 6.49 km and 13.39 km in the two groups, respectively (p=.000). ROSC differed significantly between the short and long dispatch distance groups (7.1% for short dispatch distance, 3.6% for long dispatch distance, p=.025). The length of time from to cardiopulmonary resuscitation also differed significantly between the short and long dispatch distance groups (8.77 minutes and 14.63 minutes, respectively, p=.000). Conclusion: ROSC was lower in areas of long dispatch distance compared to those of short dispatch distance. We expect this was most likely due to differences in response time by age and dispatch distance to the scene of cardiac arrest. However, no significant differences were found between the groups in the factors affecting ROSC.