Ti6Al4V 판재의 초소성 성형공정에서 Inconel 600 금형 마모 평가

방준호,송정한,김민기 한국소성∙가공학회 2024 소성가공 : 한국소성가공학회지 Vol.33 No.2

In this study, the friction and wear characteristics of Inconel 600 in the superplastic forming process of Ti6Al4V were evaluated through pin-on-disc tests. To achieve an efficient and systematic experimental design, the Taguchi method was employed. The wear track of the Inconel 600 pin showed scratches in the sliding contact direction, confirming that the wear mechanism is abrasive wear. Through sensitivity analysis such as ANOVA and Main effects, it was confirmed that both normal force and sliding distance have a significant impact on the wear. Changes in sliding velocity and distance did not affect the friction coefficient, which remained relatively constant at approximately 0.380. The wear prediction model for Inconel 600 in the superplastic forming of Ti6Al4V was constructed, which can be utilized as a guideline for the prediction and management of tool wear.

Hydrogen-driven Surface Amorphization of the In-Sn-O Thin Films

방준호,김서한,윤장희,송풍근 한국표면공학회 2021 한국표면공학회 학술발표회 초록집 Vol.2021 No.6

개선된 연속시간 전류모드 CMOS 적분기를 이용한 3.3V 능동 저역필터 구현

방준호,조성익,이성룡,권오신,신홍규 대한전자공학회 1996 전자공학회논문지-B Vol.b33 No.4

In this paper, a new continuous-time current-mode integrator as basic building block of the low-voltage analog current-mode active filters was proposed. Compared to the current-mode integrator which was proposed by Zele, the proposed current-mode integrator had higher unity gain frequency and output impedance in addition to lower power dissipation. And also, a current-mode third-order lowpass active filter was designed with the proposed current-mode integrator. The designed circuits were fabricated using the ORBIT's 1.2.mu.m double-poly double-metal CMOS n-well process. The experimental resutls of the active filter designed and fabricated for this research have shown that it has the performance of 44.5MHz cutoff frequency, 3.3mW power dissipation and the third-order active filter area was 0.12mm$^{2}$.

수치해석을 이용한 선재 롤러교정공정 주요인자의 직진도 영향 분석

방준호,송정한,이명규,이희종,성대용,배기현 한국소성∙가공학회 2022 소성가공 : 한국소성가공학회지 Vol.31 No.5

In this study, influence of the process parameters of the roller leveling process on the straightness of the steel wire was analyzed using numerical analysis. To construct the numerical analysis model, cross-sectional and longitudinal element sizes, which affect the prediction accuracy of longitudinal stress caused by bending deformation of the steel wire, were optimized, and mass scaling that satisfies prediction accuracy while reducing computational time was confirmed. By using the constructed numerical analysis model, the influence of various process parameters such as input direction of the steel wire, initial diameter of the steel wire, back tension and intermesh on the straightness was confirmed. The simulation result shows that the 3rd and 4th roller of vertical straightener had a significant influence on vertical shape of the steel wire.

새로운 구조를 갖는 CMOS 자동증폭회로 설계

방준호,조성익,김동용,김형갑 한국통신학회 1993 韓國通信學會論文誌 Vol.18 No.6

All of the CMOS analog and analog-digital systems have composed with several basic circuits, and among them, a important block, the amplifier part can affect the system's performance, Therefore, according to the uses in the system, the amplifier circuit have designed as various architectures (high-gain, low-noise, high-speed circuit, etc...). In this paper, we have proposed a new CMOS differential amplifier circuit. This circuit is differential to single ended input stage comprised of CMOS complementary gain circuits having internally biasing configurations. These architectures can be achieved the high gain and reduced the transistors for biasing. As a results of SPICE simulation with the standard $1.5{\mu}m$ processing parameter, the gain of the proposed circuit have a doubly value of the typical circuit's while maintaining other characteristics(phase margin, offset, etc...). And the proposed circuit is applicated in a simple CMOS comparator which has the settling time in 7nsec(CL=1pF) and the igh output swing $({\pm}4.5V)$. CMOS아날로그 및 아날로그 디지탈시스템은 여러 개의 기본회로로 구성되어지며 그중에서도 증폭회로 부분은 시스템의 성능을 결정할 수도 있는 중요한 블럭중에 하나이다. 증폭회로는 시스템에서 사용되어지는 용도에 따라서 여러가지 구조(고이득, 저전력, 고속회로등)를 가지며 이러한 증폭회로를 설계하기 위하여 증폭기내의 입력증폭단의 설계 방법도 다양하다. 본 논문에서는 CMOS 상보형 차동이득 구조를 갖는 새로운 형태의 입력 차동증폭 회로를 제안하였다. 제안된 회로는 CMOS 상보형 회로에 의하여 고이득 특성을 가지며, 바이어스 전류를 내부적으로 공급하여 전체 시스템 구성시, 바이어스회로를 구성하기 위한 트랜지스터의 수를 줄일 수 있다. 이 회로를 표준 $1.5{\mu}m$ 공정파라메타를 이용한 SPICE 시뮬레이션을 통하여 광범위하게 이용되고 있는 CMOS 차동증폭 회로와 비교해 본 결과, 오프셋, 위상마진등의 특성이 그대로 유지된 상태에서 이득이 배가 되었다. 또한 제안된 회로를 이용하여 높은 출력스윙(-4.5V-+4.5V)과 함께 7nsec(CL-1pF) 이하의 세틀링시간을 갖을 수 있는 CMOS비교기를 설계하였다.

죽염섭취가 혈압 및 전해질에 미치는 영향

방준호,박병윤,김동석 한국위생과학회 2002 한국위생과학회지 Vol.8 No.2

The safety of bamboo salt on human body was evaluated by a clinical study intended for 13 volunteers, who took 10 or 15 grams of bamboo salt daily for 8 weeks in addition to the regular dietary salt intake. Blood pressure and serum electrolytes(Na, K, Cl, Ca, Pi) were investigated. No significant changes of blood pressure were observed in 5 volunteers who took 10 grams of bamboo salt. The systolic and diastolic blood pressures measured before and after taking bamboo salt were at range of 115~140 mmHg and 75~101 mmHg, 118~144 mmHg and 75~104mmHg respectively. Blood pressures observed in 8 volunteers, who took 15 grams of bamboo salt, were also not significantly changed. The systolic and diastolic blood pressures of them were at range of 106~132 mmHg and 65~88 mmHg, 114~124 mmHg and 73~81mmHg respectively. The changes of Na, K, Cl, and Pi in blood serum were not also observed.

싱가포르 도심지하철 2단계 921 공구 프로젝트(DTL2 C921)

방준호,송충한,김우상,김남현,조현,Bang, Jun-Ho,Song, Chung-Han,Kim, U-Sang,Kim, Nam-Hyeon,Jo, Hyeon 한국터널지하공간학회 2011 자연, 터널 그리고 지하공간 Vol.13 No.4

군 하이브리드 네트워크에서 생존성 향상을 위한 다중 경로 멀티캐스팅

방준호,조영종,강경란,Bang, June-Ho,Cho, Young-Jong,Kang, Kyungran 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.6

In this paper, we propose a multi-path construction scheme to improve the survivability of a multicast session in military hybrid networks. A military hybrid network consists of a static backbone network and multiple mobile stub networks where some nodes are frequently susceptible to be disconnected due to link failure and node mobility. To improve the survivability of multicast sessions, we propose a construction scheme of ${\kappa}$ redundant multi-paths to each receiver. In order to take account of different characteristics of static and mobile networks, we propose quite different multi-path setup approaches for the backbone and stub networks, respectively, and combine them at the boundary point called gateway. We prove that our proposed scheme ensures that each receiver of a multicast session has ${\kappa}$ redundant paths to the common source. Through simulations, we evaluate the performance of the proposed schemes from three aspects : network survivability, recovery cost, and end-to-end delay.

터널 3차원 절대변위 해석기법을 이용한 맞장전반지반 예측

방준호,한일영 사단법인 한국터널지하공간학회 2006 한국터널지하공간학회논문집 Vol.8 No.2

Arching effect occurs around the unsupported excavation surface near to tunnel face when a tunnel is excavated in a stable rock mass. If a weak fracture zone exists in front of tunnel face, a displacement occurs between tunnel face and weak fracture zone due to stress concentration. If three-dimensional absolute coordinates (longitudinal, transverse, vertical direction) is measured at tunnel face by geodetic method, the ground change in front of the tunnel face can be predicted by analysing three-dimensional absolute displacement. The purpose of this study is to verify the analysis method of three-dimensional absolute displacement by comparing the trend of displacement ratio at crown and sidewall of tunnel and the influence line/trend line of crown settlement compared with TSP results in the same section. 안정된 암반에 터널을 굴착하는 경우 아칭효과에 의해 막장주변에 응력재배치가 발생하고 터널 막장 전방에 연약대가 존재하는 경우 응력재배치가 충분히 이루어지지 않아 막장과 연약대 사이의 응력집중으로 인해 변위가 발생하게 된다. 만일 막장에 근접하여 측점에서 종방향, 횡방향, 연직방향의 3차원 절대좌표가 측정되는 경우 막장전방의 지반거동이 반영된 3차원 절대변위가 산정되고, 이러한 3차원 절대변위의 분석을 통해 막장전방의 지반조건을 예측할 수 있게 된다. 본 연구에서는 4개 현장에서 측정된 3차원 변위비의 경향선과 천단침하의 영향선/경향선 분석을 실시하여 연약대 위치를 추정하였고, 3차원 절대변위의 분석에 의해 추정된 연약대 위치를 동일한 구간에서의 TSP탐사로 추정된 연약대 위치와 비교함으로써 3차원 절대변위 해석기법의 현장 적용성을 검증하였다.

라디칼에 대한 내화학성이 향상된 과불소계 술폰산 이오노머 막

방준호,안주희,임윤재,이창현 한국막학회 2018 한국막학회 총회 및 학술발표회 Vol.2018 No.11

Perfluorinated sulfonic acid (PFSA) ionomers have been commonly used as representative polymer electrolyte membrane (PEM) materials for fuel cell electric vehicles owing to their fast proton transport and excellent chemical resistance. However, PFSA materials still have weakness associated with chemical degradation occurring as a result from radical attacks, which induce membrane thickness reduction, leading to hydrogen crossover, and/or reduced electrochemical performances. In this study, cerium derivative radical scavengers were designed as functional additives to enhance the chemical durability of PFSA PEM. Their optimum content was suggested, comprehensively considering their radical resistance as well as other fundamental characteristics associated with long-term durability and electrochemical performance.