• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.329-332
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• 2005

Cross rolling process is one of incremental forming processes to form an axi-symmetric shaped metal component. It can be classified into two types according to the shape of dies, which are a drum type (roll type) and a plate type (straight type). It can also be classified into a wedge type and a ramp type processes according to deformation characteristics of a material. The ramp type die is applied to plate type cross rolling process in cold forming process for forming of teeth of gear or bolt, while the wedge type die is generally utilized to drum type and plate type cross rolling processes in hot forming process. A shape of the ramp type die is usually same as final shape of a product at every section of a progressing direction, while the shape of the wedge type die has different shapes in a progressing direction. In this paper, a rolling of neck part in a ball stud component has been carried out using the plate type cross rolling process with a ramp shaped die. Forming characteristics have been performed using finite element analysis in order to obtain a proper preform for the ramp type plate cross rolling process.

• 대한물리의학회지
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• 제12권2호
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• pp.53-57
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• 2017

PURPOSE: The purpose of study was to clear up the environmental risk factor that can be easily occurred unstability of hip during gait and one leg standing at various ramp angle. METHODS: Twenties healthy males of 69 subjects is participated in this study. Participants was measured activation on gluteus medius muscle during both conditions (walk across the ramp and one leg stand in the transverse direction) of seven different angle. The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition. The statistical analyses were performed using SPSS ver. 18.0 and p-value less than .05 were considered significant for all cases. A post-hoc test was performed by Bonferoni method. RESULTS: The study showed that more muscle activities on gluteus medius is increased by increasing the ramp angle. Post-hoc analysis demonstrated that the peak and mean of muscle activity increased significantly with a ramp angle of $15^{\circ}$ and $25^{\circ}$ during gait and one-leg stand. CONCLUSION: According to the study results, impaired balance can be easily occurred when cross walk and one-leg stand on a ramp from higher than $15^{\circ}$, and highest risk was angle of $25^{\circ}$ or more. As a people with gluteus medius muscle weakness walks a ramp, the ramp angle has a cross relationship with the impaired balance. If people with gluteus medius weakness walk on the more than $10^{\circ}$ of ramp angle, they will need a lot of attention for prevent impaired balance.

• PNF and Movement
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• 제15권3호
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• pp.253-257
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• 2017

Purpose: This study was conducted to predict the risks that arise while standing on mediolateral ramps at various ramp angles by identifying the ratio of medial to lateral gastrocnemius muscle activities. Methods: The subjects were 20 healthy adult men. Seven mediolateral ramp angles ($0^{\circ}$, $2^{\circ}$, $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$, and $25^{\circ}$) were applied for the experiment. The ratio of medial to lateral gastrocnemius muscle activities in each condition was measured using electromyography, and the measured data were converted to root mean square values to calculate the activity ratios. Results: The study results showed statistically significant differences in the ratio of mediolateral gastrocnemius muscle activities according to the selected mediolateral ramp angles. The results of a post hoc test confirmed that the multifidus muscles were asymmetrically used on the two sides at mediolateral ramp angles of $5^{\circ}$ or higher. Conclusion: This study found that an asymmetric use of the multifidus muscles began at a mediolateral ramp angle of $5^{\circ}$, and the provision of propulsion using the ankle joints on mediolateral ramps at $5^{\circ}$ or steeper was maneuvered differently from that on flat ground. This suggests that individuals with balance control disorder have the risk of falling due to ankle sprains and unstable balance control. Therefore, patients and elderly people are required to exercise caution when crossing $5^{\circ}$ or steeper ramps.

• Physical Therapy Rehabilitation Science
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• 제3권1호
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• pp.43-48
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• 2014

Objective: The purpose of this study was to examine the influences on gait features during mobile phone use while ramp walking. Design: Cross-sectional study. Methods: Thirty-three healthy adult subjects performed four walking conditions on an outside ramp with a 5 m length, 1.5 m width, and a $5^{\circ}$ angle. All participants were touch screen mobile phone users. Four walking conditions were used: 1) ramp ascent, 2) ramp descent, 3) texting during ramp ascent, and 4) texting during ramp descent. In conditions 3) and 4), subjects texted the words of "Aegukga"-the song of patriotism-while walking. Upon the signal of start, the subjects walked the ramp during texting. Gait parameters were measured at the length of 3 m excluding 1 m of the start and end of the total length. Each situation was repeated three times for each subject, and mean values were calculated. For gait examination, a gait analyzer was used (OptoGait). Results: Subjects ranged in age from 23 to 38 years (mean age, 27.73). Eighty-three percent of subjects in our study had experienced an accident during mobile phone use. Texting on a mobile phone while walking significantly decreased ramp gait, speed, cadence, stride length, step length, and single support (p<0.05) and significantly increased stride time, step time, gait cycle, and double support (p<0.05). There was a significant difference in cadence, step length, stride time, step time, and single support during ramp ascent and descent (p<0.05). Conclusions: Texting on a mobile phone while walking significantly decreased gait quality.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.262-267
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• 2008

Numerical investigations were performed with an external-compression inlet with a three-dimensional bump at Mach 2 to scrutinize the geometrical effects of the bump in controlling the interaction of a shock wave with a boundary layer. The inlet was designed for two oblique shock waves and a terminal normal shock wave followed by a subsonic diffuser, with a circular cross-section throughout. The bump-type inlet that replaced the aft ramp of the conventional ramp-type inlet was optimized with respect to the inlet performance parameters as well as compared with the conventional ramp-type inlet. The current numerical simulations showed that a bump-type inlet can provide an improvement in the total pressure recovery downstream of the shock wave/boundary layer interaction over a conventional ramp-type inlet.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.262-267
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• 2008

Numerical investigations were performed with an external-compression inlet with a three-dimensional bump at Mach 2 to scrutinize the geometrical effects of the bump in controlling the interaction of a shock wave with a boundary layer. The inlet was designed for two oblique shock waves and a terminal normal shock wave followed by a subsonic diffuser, with a circular cross-section throughout. The bump-type inlet that replaced the aft ramp of the conventional ramp-type inlet was optimized with respect to the inlet performance parameters as well as compared with the conventional ramp-type inlet. The current numerical simulations showed that a bump-type inlet can provide an improvement in the total pressure recovery downstream of the shock wave/boundary layer interaction over a conventional ramp-type inlet.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.77-83
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• 2004

on-chip 상에서 발생하는 누화 잡음은 신호의 충실성을 위협하는 매우 중요한 요소이다. 따라서 본 논문에서는 최대 누화잡음의 크기를 예측하는 해석적인 방법을 제안한다. 정확한 잡음 수치를 예측하기 위해 연결선의 인덕턴스 성분을 고려하였고, 임의의 램프입력을 사용하였다. 또한 복잡한 누화 잡음 모형에서 최대 누화 잡음을 해석적으로 간단히 구하기 위해 가상의 소스 개념을 도입하였다. 된 연구에서 제안한 방법은 HSPICE 시뮬레이션 결과와 비교하여 최대 상대오차 4.3％ 이내의 정확도를 보였다. 따라서 본 연구는 신호 충실성 보장을 위한 다양한 설계 보조 도구 개발에 활용될 수 있을 것으로 본다.

• 한국실내디자인학회논문집
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• 제18권6호
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• pp.104-114
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• 2009

The purpose of study was understanding necessity of environment design for underground parking lot in residential design plan and grasping design plans of 'Activity Support' that considerate women, exclude women's unsecured feeling at underground parking lot. The inquiry analyzed 6 design plan in design competition that considerate women according to precede studies, a theory of CPTED, a design guide for wayfinding, and survey. A ramp, circulation, entrance, lighting, ventilation, and space design plan are proceed on this study The result are as below. First, a rectilinear figure ramp suits entrance plan on the circulation, but if it is not possible, cross-using of rectilinear and curvilinear figure ramp plan is desirable. Second, on the circulation plan, vehicles circulation plan and equality parking distribution plan got accomplished generally, and help senses of direction because it is planed network systemize. On a large scale underground parking lot, simplify parking circulation to convenience entrance and exit for weak in sense of direction. Third, the shape and material that‘s environmentally conscious will be in use to the entrance plan. As the first stage to the underground, artwork that women prefer can modulate the rejection of underground space. Forth, natural lighting system and ventilation can make the environment-friendly space, decrease the women’s rejection to the underground, it can also keep a natural watch on the space. Fifth, on the space design plan, it can use bright and comfortable design of wall and ground to decrease the women‘s rejection, also it is useful to the sense of direction. LED indirect lighting plan that 58.7% of women prefers on survey reflects women’s state of desire that bright and atmosphere. In addition, proper use of plans that subsidiary facilities, rest area with Sunken, and nature-friendly material can minimize differences of underground and ground parking lot.

• 자원환경지질
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• 제29권3호
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• pp.345-355
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• 1996

2차원 지하구조를 해석함에 있어 1차원 역산에 근거한 수직탐사자료 해석의 타당성과 수평탐사에 있어 여러가지 전극배열법의 효율성이 연구되었다. 수직암맥, 판상기둥, 매몰수직단층, 램프 (ramp), 복합구조와 같은 2차원 모델로부터 유한차분법을 이용하여 3 포인트, 쌍극자, 베너 (Wenner), 슐럼버저 (Schlumberger) 수평탐사의 겉보기비저항 곡선을 구하고 이를 비교 분석하였다. 수직탐사의 경우에는 슐럼버저와 베너 배열법에 대하여 1차원 역산자료를 내심하여 얻은 자료로부터 2차원 단면도를 구하여 비교하였다. 이러한 2차원 단면도는 각 모델에 대하여 비저항의 수칙, 수평적인 경계면을 잘 보여주고 있다. 또한 슐럼버저 수평탐사의 겉보기 비저항 곡선은 수직적인 비저항의 경계면을 잘 보여주고 있다. 전반적으로 수직, 수평 전기탐사의 경우에 있어 슐럼버저 배열법이 다른 전극배열법보다 우수한 결과를 보여주고 있다. 본 연구로부터, 1차원 역산에 근거한 2차원 지하구조의 해석이 가능함을 알 수 있다.

• 대한전자공학회논문지SD
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• 제47권6호
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• pp.13-21
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• 2010

본 논문에서는 가변 펌핑 클록 주파수를 이용한 모바일 D랩용 고효율 승압 전압 발생기를 제안한다. 제안된 승압 전압 발생기는 효율을 높이기 위해서 3단 Cross-coupled 점하 펌프를 사용하였으며, 또한 최종 출력 전압의 승압 시간을 줄이기 위해 기존의 승압 전압 발생기에서 사용되는 고정된 펌핑 클록 주파수 대신 전압 제어 발생기를 사용하여 펌핑 클록 주파수을 가변하였다. 따라서 제안된 승압 전압 발생기는 1.2 V 전원 전압, 최대 2 mA의 부하 전류, 1 nF의 부하 캐퍼시터 조건에서 24.0-${\mu}s$안에 3.0 V의 최종 출력 전압을 승압할 수 있다. 실험 결과 제안된 승압 전압 발생기는 에너지 소비를 26% (1573 nJ $\rightarrow$ 1162 nJ), 승압 시간을 29% (33.7-${\mu}s$ $\rightarrow$ 24.0-${\mu}s$) 감소시켰다. 따라서 제안된 승압 전압 발생기를 사용함으로써, 높은 에너지 효율과 빠른 승압을 동시에 구현할 수 있다.