• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1939-1944
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• 2020

Pool boiling heat transfer of a copper microporous coating was experimentally studied in borated water with a concentration of boric acid from 0.0 to 5.0 vol percent (vol%) to determine the effect of boric acid on boiling heat transfer in water. A high-temperature, thermally conductive microporous coating (HTCMC) was created by sintering copper powder with an average particle size of 67 ㎛ onto a 1 cm × 1 cm plain copper surface with a coating thickness of ~300 ㎛ within a furnace in a vacuum environment. The tests showed that the nucleate boiling heat transfer coefficient (NBHT) of HTCMC became slightly less enhanced as the concentration of boric acid increased but the NBHT coefficient values were still significantly higher than those of the plain surface. The critical heat flux (CHF) values from 0 to 1.0 vol% were maintained at ~2,000 kW/㎡, and then, they gradually decreased down to ~1,700 kW/㎡ as the concentration increased further to 5.0 vol%. It is believed that the micro-scale pores of the HTCMC were partially blocked by the high boric acid concentration during the nucleate boiling such that the small bubbles were not effectively created using the HTCMC reentrant cavities as the boric acid concentration increased.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.102-102
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• 2016

Water, which is most abundant in Earth surface and very closely related to all forms of living organisms, has a simple molecular structure but exhibits very unique physical and chemical properties. Even though tremendous effort has been paid to understand this nature's core substance, there amazingly still lefts much room for scientist to explore its novel behaviors. Especially, as the scale goes down to nano-regime, water shows extraordinary properties that are not observable in bulk state. One of such interesting features is the formation of nanoscale bubbles showing unusual long-term stability. Nanobubbles can be spontaneously formed in water on hydrophobic surface or by decompression of gas-saturated liquid. In addition, the nanobubbles can be generated during electrochemical reaction at normal hydrogen electrode (NHE), which possibly distorts the standard reduction potential at NHE as the surface nanobubble screens the reaction with electrolyte solution. However, the real-time evolution of these nanobubbles has been hardly studied owing to the lack of proper imaging tools in liquid phase at nanoscale. Here we demonstrate, for the first time, that the behaviors of nanobubbles can be visualized by in situ transmission electron microscope (TEM), utilizing graphene as liquid cell membrane. The results indicate that there is a critical radius that determines the long-term stability of nanobubbles. In addition, we find two different pathways of nanobubble growth: i) Ostwald ripening of large and small nanobubbles and ii) coalescence of similar-sized nanobubbles. We also observe that the nucleation and growth of nanoparticles and the self-assembly of biomolecules are catalyzed at the nanobubble interface. Our finding is expected to provide a deeper insight to understand unusual chemical, biological and environmental phenomena where nanoscale gas-state is involved.

• 대한지리학회지
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• 제1권
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• pp.67-82
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• 1963

본 연구는 낙안읍성이라는 특정 장소에서 열리는 남도음식축제를 사례로 이벤트관광의 정착과 성장과정을 관광지리학적 관점에서 고찰하였다. 남도음식축제는 특정장소가 갖는 매력요인과 전남지역의 고유한 향토음식이 결합된 전남의 대표적인 이벤트관광이며, 1998년 문체부에 의해 전국 3대 축제로 선정되어 전국적인 규모의 축제로 성장하였다. 1994년부터 시작된 남도음식축제는 프로그램과 예산, 참가인원 등 규모면에서 꾸준한 성장을 보여 왔다. 그리고 개최기간은 3일에서 일주일로 연장되었고, 관광세력권은 꾸준히 확대되고 있다. 남도음식축제를 더욱 활성화시키기 위해서는 관 주도의 축제에서 민간주도의 축제로의 전환, 지역축제를 이끌어 갈 전문인력의 양성, 낙안읍성이라는 장소성과 역사성을 부각시킬수 있는 프로그램 개발, 음식축제에 대한 보다 적극적인 경영마인드의 도입, 낙안읍성 주변의 주요 관광지와 연계관계를 구축하여 관광세력권의 확대, 지속적인 관광객 형태 및 평가분석을 통한 관광객들의 관심과 욕구의 반영 등이 필요하다.

• 대한조선학회논문집
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• 제37권3호
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• pp.57-68
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• 2000

이착륙 속력을 줄이기 위해 날개 밑으로 프로펠러 후류를 불어넣어 날개와 수면사이의 압력을 증가시키는 PAR(Power Augmented Ram) 효과는 해면효과익선의 성능을 크게 향상시킨다. 본 논문에서는 풍동실험을 통해 이러한 PARWIG(Wing in Ground)선의 공력특성을 연구하였으며 송풍기(blower)와 덕트(duct)를 사용한 제트분사를 프로펠러 후류로 대신하였다. 제트의 분사속도, 분사위치(수평 및 수직 방향), 분사각 및 덕트 직경 변화에 대해 20인승 PARWIG선의 1/25 축소 모형선의 지면과의 고도, 앙각 및 플랩각의 변화에 따른 양력, 항력 및 피치모멘트를 계측하여 공력특성을 비교하였다. 적절한 PAR효과의 사용은 양력을 크게 증가시키며 최대 4의 양력계수까지 얻을 수 있었다.

• 대한족부족관절학회지
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• 제10권1호
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• pp.37-41
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• 2006

Purpose: To investigate the early results of limited open repair technique of Achilles tendon ruptures, and to describe the surgical technique. Materials and Methods: From October 2004 to February 2005, a total of 10 patients with Achilles tendon rupture underwent limited open repair. The average age of the patients was 39.3 years, and the average follow-up period was 9 months. The causes of injury were sports injuries in 8 cases, and slip down in 2. The mean interval between the injury and the operation was 9 days. The clinical results were assessed by patient's satisfaction, incision length, hospitalization, the ankle-hindfoot scale of American Foot and Ankle Society (AOFAS), and complications. Results: Of 10 patients, 8 were very satisfied, and the remaining 2 were satisfied. The mean incision length was 2.0 cm, and the mean hospitalization was 2 days. The mean AOFAS score was 97 points, and there was no complications such as infection, rerupture, or nerve injury. All patients returned to work at approximately 2 months, and resumed light exercise such as jogging at approximately 3 months. Conclusion: Limited open repair technique of Achilles tendon ruptures is provided for better cosmetic results, high patient's satisfaction, and functionally successful results without postoperative complications.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.280-288
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• 2014

SDC (Samarium doped Ceria) electrolyte was developed for Intermediate temperature SOFC ($500^{\circ}C-800^{\circ}C$) which showed a good electrical conductivity. In this study, we used sintering aids to reduce the SDC sintering temperature down to $1000^{\circ}C$, especially which can help the SOFC scale-up. In order to reduce the SDC sintering temperature, $Li_2CO_3$ and $TiO_2$ were used as a sinering aids for decreasing sintering temperature. $Li_2CO_3$ and $TiO_2$ doped SDC sintered at $1000^{\circ}C$ showed 99% of the theoretical density and higher electrical conductivity than the pure SDC sintered at $1500^{\circ}C$. When measuring the OCV (Open circuit voltage) with the $Li_2CO_3$ and $TiO_2$ doped SDC electrolyte, however, the OCV values were lower than the theoretical OCV values which means that the modified SDC still had electronic conductivity.

• 융합보안논문지
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• 제6권1호
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• pp.1-11
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• 2006

최근 사이버테러의 급증은 정보사회의 근간을 위협하고 있고, 특히 악성 트래픽에 의한 네트워크마비는 단 시간 내에 국가적인 손실을 초래할 수 있어 이에 대한 대비책이 시급히 요구되고 있다. 이와 관련, 국가사이버안전 위협에 대한 신속한 대처능력확보를 위해 국가사이버위협 조기 예 경보시스템에 대해 많은 연구가 이루어지고 있으나 기술적인 문제와 함께 시스템의 효용성에 대한 한계 때문에 실용적인 연구가 가시화되지 못하고 있는 실정이다. 현재까지는 ESM, TMS 등을 이용한 제한적 자료수집분석을 통하여 보안관리자가 개개인의 경험을 바탕으로 예 경보 판단을 내려왔다. 이러한 판단은 상황에 따라 극히 위험한 결과를 초래 할 수도 있다. 이러한 문제점을 방지하기 위해 본 논문에서는 "지식기반을 이용한 실시간 사이버위협 조기 예 경보시스템"을 제안하였다. 제안된 시스템은 향후 사이버공격에 대해 체계적이고 보다 정확한 예 경보 판단을 내리는데 사용할 수 있다.

• 생태와환경
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• 제45권4호
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• pp.347-355
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• 2012

In this study, non-point pollution sources in the Yeongsan river basin are analyzed; then, the priority regions (areas divided on a small scale) of management are selected for efficient water management of the Seungcheon and Jooksan reservoirs, which were constructed as one of the 4 major rivers restoration projects. The priority regions are decided by using the criteria of the excessive rate of target water quality, non-point pollution load per unit area, total TP load and down flow distance. The results of this study are as follows. The upper 10% of the priority regions for non-point pollution management includes YB15, YB05, YB10, YB24, YB14 and YB11 for the Seungcheon reservoir watershed, and YC24, YC25, YC30, YC34, YC22 and YC17 for the Jooksan reservoir watershed. However, a few regions in each of the Seungcheon and Jooksan reservoirs need to be selected in higher order, and the non-point pollution removal facilities in the regions need to be installed with respect to budget, urgent matter, and so on.

• 근관절건강학회지
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• 제6권1호
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• pp.7-21
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• 1999

This study attempts to provide the rudimentary data that might help patients with Rheumatoid Arthritis manage an independent life by the analysis of their activities of daily living(ADL). The subjects were forty patients who had been diagnosed Rheumatoid Arthritis and under drug therapy from RA clinics of the two university hospitals in Pusan. Data were collected by performing an individual interview for each of them during June 15th through July 15th 1998. Questionaires were imployed to investigate the general characteristics of patients. the traits of Rheumatoid Arthritis, and actual conditions of their activities of daily living. The questionaires utilized especially for the study of ADL is the version of Lee Eun Ok's tool which modified and complemented Katz scale (Katz, Down, Cogh and Grots 1970) and Bathel index(Bathel. 1973). It's consisted of 31 questions that each question is measured by 0-3points. The high score in the questionaire signifies the high independency in the ADL. The data were analyzed by SPSS/Win in terms of frequency, percentage, mean, and standard deviation, close connection with the contents of the personal interview. Total mean of the ADL shows $1.55{\pm}0.68$, indicating the overall activities of daily living is generally dependent. It also indicates that patients, in the condition of dependent activity. tends either to have recourse to drugs or to take negative strategy, getting help from inside or outside family member. Hence, it is necessary that patients are exposed to the introduction and instruction of self-help devies that might help them manage a comparatively independent ADL, easing their paychological burden.

• 한국수자원학회논문집
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• 제45권11호
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• pp.1121-1130
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• 2012

낙동강 미래 기후변화 시나리오 추출을 위해 CGHR(T63) 모형과 A1B 온실가스 배출시나리오를 통계적 규모내림방법으로 대상유역의 규모로 축소 변환한 후, 수문 수질의 거동변화 등의 영향을 모의하기 위해 SS와 T-P를 대상으로 SWAT 모델을 적용하였다. 과거 30년 자료와 비교한 결과, 지표유출은 지역에 따라 최대 60%까지, 오염배출부하는 TSS와 T-P의 경우 각각 35~45%, 5~20%정도 변화되어, 미래 기후변화로 인한 지표유출과 오염부하 배출은 향후 뚜렷한 증가가 예상된다. 또한, 그 증가 경향은 낙동강 하류지역보다 상류지역에 크게 나타나며 계절별로는 겨울과 봄철의 증가가 크고 먼 미래로 갈수록 증가하는 반면, 여름과 가을철에는 먼 미래로 갈수록 증가율이 감소하는 경향을 나타내어 갈수기 지표수 수질에 부정적인 영향을 미칠 것으로 예측된다.