In this study, two ventilation holes were considered to prevent condensation in the circular column supporting the provision crane on a training ship(Saenuri) for Mokpo National Maritime University. The ventilation holes could be understood as the most simple and inexpensive way to prevent condensation because it was formed only by drilling. If sufficient ventilation is provided, the insulation and corrosion of an electric motor can be improved, and a comfortable state can be ensured in the circular column. The circular column had an electric motor for driving the provision crane so that the basic principle was to utilize the kinetic energy for the flow field from a cooling fan in the circular column. The ventilation holes attenuated the low-velocity area in the circular column and contributed to internal flow circulation with updrafts. The results were discussed through numerical analysis based on computational fluid dynamics.

본 논문의 주된 연구목적은 인구이동 플로의 지리적 시각화를 위한 개념적 명료화를 수행하고, 그것에 의거해 우리나라 인구이동 데이터를 사례로 다양한 주제도의 예시를 제공하는 것이다. 공간적 스케일 개념에 대한 심도 깊은 논의를 바탕으로 인구이동 연구를 위한 공간적 프레임워크가 제시되었다. 인구이동 관련 측도들의 다양성이 측도의 성격과 측도의 공간적 스케일이 라는 두 축에 의거한 유형 분류 체계를 통해 제시되었다. 측도의 다양한 성격을 세 가지 주요 주제도 유형(도형표현도, 코로플레스맵, 유선도)과 결합하는 원리가 제시되었다. 우리나라 2020년 시군구 단위 인구이동 플로 데이터에 대해 세 가지 지역 스케일별로 주제도 제작의 사례가 제공되었다. 지역별 수준에서는 순이동과 순이동률에 대한 일종의 이변량 도형표현도, 인구이동 영향력에 대한 코로플레스맵, 자족도에 대한 코로플레스맵이 제시되었다. 지역-특수적 수준에서는 행-표준화 지도와 열-표준화 지도가 도형표현도와 단계구분도의 형태로 제시되었다. 지역간 수준에서는 스트림 영향력 지도와 탁월류 분석 지도가 유선도 형태로 제시되었다. 본 연구는 단순한 시각화를 넘어 인구이동 플로 데이터에 대한 탐색적 공간데이터 분석을 진작한다는 측면에서 의의가 있는 것으로 평가된다.

In this study, the uniformity of the horizontal velocity and the temperature of each zone were investigated by computerized analysis method to divide the drying room into three multi - rooms to ensure the uniformity of flow inside the forced convection hot air dryer. The internal structure of the drying room of the dryer was modeled using Solidworks. In order to control the flow of hot air circulating in the drying chamber, the possibility of controlling the horizontal flow inside the drying room was verified by using a perforated plate, a guide vane, and a vertical plate. From the results of the flow visualization in the drying room, it was understood that the internal flows of the dryer models 1, 2 and 3 change from ununiform flow to uniform flow. From the analysis of velocity and temperature fluctuation, the results of the analysis of the dryer model 3 satisfied the design conditions.

Abstract The increase of the superheat is one of several factors adversely affecting the efficiency of the refrigeration cycle. To this end, it is important to release the heat inside the compressor. Therefore, in this paper, we have increased the convective heat transfer coefficient inside the compressor by utilizing the vibration of the moving part of the compressor. The results show that reducing the gap between the shell and the moving part increases the flow velocity in the gap resulting in the increase of convective heat transfer coefficient.

본 연구는 원심펌프 내부 유동장 특성에 대한 시뮬레이션 및 시각화에 중점을 둔다. 3D 수치해석은 Reynolds Average Navier-stock 코드를 k-Ɛ 표준 2차방정식 난류 모델로 처리하여 수행하였다. 시뮬레이션은 흡입측, 임펠러, 토출측 영역에서 조도로 인한 마찰 손실과 임펠러 웨어링에서 체적 손실을 포함한다. 해석과 실험사이의 성능곡선 비교결과 최대 5 %의 작은 차이를 보이며 동일한 추세를 나타냈다. 최고 효율점에서 속도 벡터는 고르게 나타났지만 비 설계점에서는 현저한 변화가 나타났고, 텅 부근의 임펠러 유로토출부에서 강력한 재순환 영역이 나타났다. 비교적 일정한 압력분포가 텅 부근임에도 불구하고 임펠러 주위에 관찰되었다. 볼류트 내에서 기하학적으로 인해 형성된 나선형 와류가 이 영역에서 유동장이 상대적으로 난류이고 불안정하다는 것을 증명하였다.

This study is done as a comparison analysis on existing studies on analysis and interpretations of solenoids. When there is no power in a solenoid valve, a flow passage is formed from a pressurized ports, Pc, to Ps, which are connected to a crankcase of a pressurizer. An inlet to Pc port is varied in three different sizes: 3.8 ㎜(Type-1), 4.0 ㎜(Type-2) and 4.2 ㎜(Type-3). It is determined that there will be changes in coolant flow into the solenoid valve and the flow properties from Pc port to Ps port are compared and analyzed. As the results, the flow demonstrates the maximum speed of 500 ㎧, 46 ㎧ and 433 ㎧ with 0.2 ㎫ for the inflow pressure and the maximum speed of 1400 ㎧, 129 ㎧ and 1200 ㎧ with 1.5 ㎫ for the inflow pressure.

This paper carried out a comparative analysis with papers on the analysis and analytic research of conventional solenoid. In case the current of solenoid valve is cut off, a flow path is formed from pressure port (Pc) connected with the crankcase of compressor to Ps port. At this time, the size of Pc port hole was so adjusted (Type-2) that it was smaller than 4.0mm(Type-1) of original hole by 0.2mm. After that, it was thought that an effect would be produced on the flow change of refrigerant which came into the solenoid vale, therefore the flow characteristics in moving from Pc port to Ps port was predicted and comparatively analyzed. According to the results of flow analysis, a velocity of approximately 46m/s and 129m/s was shown at the maximum in case of 0.2 and 1.5 MPa in Type-1, and the maximum velocity of approximately 500m/s and 1400m/s was shown in case of Type-2.

Numerical analysis of the electric vehicle battery was performed for the optimization of the thermal management under various operating conditions. For the analysis of internal flow and temperature distributions under the different operating conditions of battery, the battery system which was packed 18 battery cell with -25℃∼ 65℃ operating temperature range was considered, and the air flow rate, velocity, and ambient temperature conditions were varied and compared. It was revealed that the cooling system for battery was necessary to maintain its performance for hot ambient conditions. Especially, in this condition, at least 90m3/h of air flow rate are required to maintain the module temperature under 40℃. However, heating system of battery for cold ambient conditions doesn't need.

본 연구는 콘덴싱 보일러 내부에 들어가는 원심 터보형 송풍기의 성능 향상 및 그 유동특성을 파악하고자 하였다. 보일러는 연소를 위해 반드시 필요한 가스와 공기의 양이 조절되어야하며, 이를 위해 송풍기는 보일러 내부의 한정된 영역을 차지한다. 한정된 영역에서 최적의 효율을 얻기 위해서는 케이싱 및 임펠러의 형상을 변경하는 것이 일반적으로 사용되며, 형상변화에 따른 입/출구압력, 유량, 임펠러의 토크 등의 성능특성을 파악하였다. MRF(Multiple Rotating Frame)기법 및 k-ù SST 난류 모델을 적용하여 회전 임펠러에 대한 수치해석을 수행하였으며, 형상의 변경에 따라 송풍기의 성능특성 및 최적화된 설계형상을 제안하였고, 압력측정실험을 통해 그 결과를 검증하였다.

The pear psylla, Cacopsylla pyricola Foerster (Homoptera: Psyllidae), is a serious insect pest of commercial pear crops. The species, which resides on pear trees throughout its life cycle, is rapidly spreading in some regions of the world. Given the life cycle, it is unclear how such a rapid spread has been facilitated. Presently, the population genetic structure of the species including genetic diversity and gene flow was studied to understand the nature of dispersal and field ecology of the species. Pear psylla was collected from several pear orchards in Korea. The 658-bp region of mitochondrial COI gene and the 716-bp long complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA were sequenced. Unlikely other previously studied insect pests, the COI-based genetic diversity of the pear psylla was extremely low (maximum sequence divergence of 0.15%). This finding allowed us to conclude that the species may have been introduced in Korea relatively recently, possibly with the phenomenon of genetic bottlenecks. ITS2 sequence-based analyses of phylogeny, population differentiation, gene flow, and hierarchical population structure all concordantly suggested that the pear psylla populations in Korea are neither genetically isolated nor hampered for gene flow. These genetic data are concordant with the dispersal of an overwintering winterform morph outside the non-pear habitat in the fall and the possibility of subsequently longer distant dispersal.

The aim of this is to examine the effects of SSP therapy on the internal carotid arteries blood flow of 24 tension type headache patients(study group) and non tension type headache patients(control group), and on the reduction of their headaches, when applied to the acupuncture points. It stimulated the acupuncture point of headache 6 place with the SSP. It measured VAS and the blood flow of the internal carotid arteries with TCD. When the internal carotid arteries blood flow of study group and control group were compared by period, a significant difference was found in the 4th period(p<.05). When the Visual Analog Scale of study group and control group were compared by period, a significant difference was found in the 4th period(p<.05). The comparison of each measurement result of the internal carotid arteries blood flow of the study group found significantly increased. The comparison of each measurement result of the VAS of study group found significantly decreased. With regard to the control group, the VAS significantly decreased. The silver spike point low frequency electrical stimulation treatment, when applied to the acupuncture point, can significantly influence the internal carotid arteries blood flow of headache patients and can significantly reduce their headaches.

With continuous industrial development, the types, and amount of particulate matter (PM) have been increasing. Since 2018, environmental standards regarding PM have become more stringent. Pulse air jet bag filters are suitable for PM under the 20㎛ and, can function regardless of size, concentration and type. Filtration velocity and shape are important factors in the operation and design of the pulse air jet bag filters however, few established studies support this theory. In this research, numerical simulations were conducted based on experimental values and, several methods were employed for minimizing the pressure drop. In the pilot system, as the inlet duct velocity was faster than 19 m/sec, flow was not distributed equally and, re-entrainment occurred due to the hopper directional vortex. The multi-inlet system decelerated the hopper directional vortex by 25 ~ 30% , thereby decreasing total pressure drop by 6.6 ~ 14.7%. The guide vane system blocked the hopper directional vortex, which resulted optimal vane angle of 53°. The total pressure of the guide vane system increased by 0.5 ~ 3% at 1.5 m/min conditions. However, the filtration pressure drop decreased by 4.8 ~ 12.3% in all conditions, thereby reducing the operating cost of filter bags.

다양한 내부경계를 포함하는 폐합형 하천수계에 대한 부정류 계산모형을 개발하였다. 계산모형은 폐합형 수계모형으로서, 계산기법으로는 Preissmann의 4점 음해법과 폐합형 double sweep 알고리즘에 근거한 모형을 사용하였다. 또한 댐 및 수중보 등의 수공구조물에서 발생할 수 있는 월류흐름, 오리피스형 흐름 등에 대한 모의가 가능하도록 하고, Auto ROM에 의한 댐에서의 홍수조절 방안을 내부경계 조건으로 포함하여 홍수시 운영조건에 대한 모의가