• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.393-393
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• 2022

상수도관망의 압력은 물공급 서비스의 질을 나타내는 중요한 인자이다. 압력이 낮으면 물 사용성이 크게 저하되며, 이러한 이유로 보통의 수도사업자는 압력을 중요한 모니터링 변수로 고려하고 있다. 압력을 기반으로 여러 가지 변수를 계산할 수 있지만, 그 중에서도 압력경사(Pressure Head Gradient)는 수요량, 관경, 관의 파괴 등 독립변수 또는 독립요인의 변화에 따른 종속변수로서의 압력 민감도를 나타낸다. 압력경사의 계산은 매우 간단하면서도 활용도가 높다. 따라서, 다양한 종류의 압력경사를 계산하고, 상수도관망 설계, 운영, 관리 목적에 어떻게 사용할 것인가를 연구할 필요가 있다. 본 연구에서는 먼저 관의 상태, 관경, 절점수요량을 독립변수로 하고 이를 변화시켜 그 결과로의 압력종속변수를 계산, 압력경사를 결정하였다. 이를 기반으로, 히트맵을 구축하여 결과를 비교하였다. 그 후 각각의 압력경사에 대한 모듈을 구축하였으며, 개별 압력경사 모듈의 특징을 고려하여 활용방법을 수립하였다.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.257-265
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• 2010

The purpose of this study was to investigate the effect of different ramp inclination on the maximum plantar foot pressure and pathway of the center of pressure. Fifteen healthy adults who had no musculoskeletal disorders were participated with this study and descended the ramp with different inclination(level, $-5^{\circ}$, $-10^{\circ}$, $-15^{\circ}$). Plantar foot pressures were recorded by the Matscan system(Tekscan, Boston, USA) during level and descending ramp with barefoot. Plantar foot surface was defined as seven regions for pressure measurement; two toe regions, three forefoot regions, one midfoot region, one heel region. Repeated ANOVA was used to compare each region data of foot according to different ramp inclination. As descending ramp inclination became increased, the pressure of hallux region was significantly increased at $-15^{\circ}$ inclination and the pressure of 2-3 metatasal head region were significantly decreased at $-5^{\circ}$, $-10^{\circ}$, $-15^{\circ}$ inclination. The pathway of COP had a tendency to be shifted inside in forefoot and prolonged to great toe as the descending ramp inclination increased. The results indicated that plantar foot pressure could be changed at hallux and forefoot regions with $-5^{\circ}$ ramp inclination and these findings demonstrated that ramp inclination could affect the structure and function of foot.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.59-65
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• 2008

The purpose of this study was to investigate the shift of COP pathway and the plantar foot pressure among level walking and stairs and ramp climbing in young and elderly people. Plantar foot pressure was measured by MatScan system(Tekscan, USA). Statistical analysis was used One-way ANOVA to know the characteristics of peak plantar pressure during walking with different the facilities. In young adults, COP pathway during stairs climbing was slightly shorten and trended to abduct at forefoot. COP pathway during ramp climbing was also shorten but trend to adduct at forefoot. Peak plantar pressure of 2-3 metatarsal head and heel during ramp climbing was more decreased than level walking. In elderly people, COP pathway during stairs climbing was more shorten and abducted than leve walking and COP pathway during ramp climbing was more unstable than level walking. Peak plantar pressure of first metatarsal head increased at stair climbing and decreased at ramp climbing. That of second metatarsal head and heel was more decreased at ramp climbing. Conclusionally, Peak plantar pressures of each foot region generally increased and more changed during ramp climbing.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.208-213
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• 2006

경사진 안창은 안창의 경사로 발의 자세를 교정함으로써 하지 통증을 완화시키는 데 사용되는 보조치료기구로 내측 경사진 안창(MWI: medially wedged insole)과 외측 경사진 안창(LWI: laterlly wedged insole)으로 나뉜다. 본 연구는 내/외측 경사진 안창이 족부압력에 미치는 영향을 정량적으로 분석하고자 한다. 분석변수는 압력중심(COP: center of pressure)의 궤적 변화, 발바닥 내 세 개 구획에 상대적으로 작용하는 수직 힘(RVF: relative vertical force) 그리고 여덟 개 해부학적 지점의 압력이다. 경사진 안창의 경사조건은 내/외측 각각 $5^{\circ},\;8^{\circ},\;15^{\circ}$이며, 경사가 없는 안창을 포함해 총 일곱 가지 안창이 실험에 사용되었다. 실험참여자로는 20대 성인 남성 10명이 참여하였다. 실험결과 앞발 누름기에서 MWI와 LWI는 모두 COP를 내측으로 이동시키고 외측 압력을 감소시켰다. 뒤축 접지기에서 MWI는 COP를 내측으로 이동 시키고 내측압력을 증가시키는 반면, LWI는 COP를 외측으로 이동시키고 외측압력을 증가시켰다. 그리고 RVF 분석결과 MWI와 LWI는 모두 앞발 부위 힘의 크기를 감소시켰고, LWI만이 발 뒤축 부위 힘의 크기를 증가시켰다.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.10-18
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• 2019

In this study, flow characteristics and the starting pressure of a center body diffuser (CBD) were analyzed at various center body (CB) positions and cone angles. According to the CB position, the location of oblique shock moved to the front from behind the CB cone with an increase in the flow momentum. Additionally, when a strong oblique shock occurred, the direction of supersonic flow was affected and induced to diffuser wall. As a function of different cone angles for the oblique shock, the starting pressure of the CBD was significantly affected.

• Journal of Korea Water Resources Association
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• v.47 no.12
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• pp.1177-1185
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• 2014

This study suggests a new hydrostatic pressure distribution corrected for nonuniform flow over a channel of large slope. For analyzing shallow-water flows over large slope accurately, it is developed a finite-volume model incorporating the pressure distribution to the shallow water equations. Traveling speed of the hydraulic jump downstream a parabolic bump in the drain case is quite reduced by the weakened bottom gradient source term in the model with the pressure correction. In simulating the dam-break flow over a triangular sill, it is identified that the model with pressure correction could capture the water surface by the digital imaging measurements more than the model without that. Due to the pressure correction decreasing the reflected flows on and increasing overflows over the sill, there are good agreements in the experiment and the simulation with that. Therefore, this model is expected to be applied to such practical problems as flows in the spillway of dam or run-up on the beach.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.27-33
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• 2006

This paper investigates leak effect on the outlet pressure at pipeline exit. A modified Weymouth equation(including inclination effect) was used for this study. To investigate leak effect, outlet pressure and ratio of outlet to inlet pressure were compared between no leak and leak conditions for horizontal, upward and downward flows, respectively. Then, effects of leak location as well as leak rate on the outlet pressure were also investigated for all pipeline inclinations.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.49-55
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• 2003

In this study, based on the relationship of the vertical force - settlement of batter piles obtained by pressure chamber model tests, the vertical bearing capacity of vertical and batter piles according to the increase of pile inclination was analyzed. A model open - ended steel pipe pile with the inclination of 5$^\circ$, 10$^\circ$ and 15$^\circ$ was driven into saturated fine sand with relative density of 50 %, and the static compression load tests were performed under each confining pressure of 35, 70 and 120 kPa in pressure chamber. The vertical bearing capacity of pile obtained from pressure chamber tests increased with the pile inclination. In the case of the inclination of 5$^\circ$, 10$^\circ$, 15$^\circ$, increasing ratios of pile bearing capacity were 111, 121, 127 ~ 140 % of vertical bearing capacity respectively. In the case of the inclination of above 20$^\circ$, the model tests could not be performed because of pile of pile head during compressive loading on the pile head.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.113-118
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• 2004

Experiments are conducted to get basic information of under-expanded impinging jet in the near field. Experimental parameters are impinging angle and under-expanded ratio. As the under-expanded ratio increases, the maximum surface pressure decreases and the reducing effect of recovery factor increases. As the impinging angle decreases, the peak of surface pressure is displaced slightly from the geometric center of the plate to the upward region and the cooling region is expanded in the downward region, whereas it is contracted in the upward region.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.465-471
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• 2003

A coastwise chemical tanker sailing at full speed has capsized during turning in calm water. In the previous paper, we investigated the reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and increased the vertical distance between the center of gravity of the ship and the center of lateral water drag.