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.

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.

Microbiological Characteristics of Acute Prostatitis After Transrectal Prostate Biopsy

방준호,최현섭,이동섭,이승주,조용현 대한비뇨의학회 2013 Investigative and Clinical Urology Vol.54 No.2

Purpose: We aimed to identify microbiological characteristics in patients with acute prostatitis after transrectal prostate biopsy to provide guidance in the review of prevention and treatment protocols. Materials and Methods: A retrospective analysis of medical records was performed in 1,814 cases who underwent prostate biopsy at Seoul St. Mary’s Hospital and St. Vincent’s Hospital over a 5 year period from 2006 to 2011. Cases in which acute prostatitis occurred within 7 days after the biopsy were investigated. Before starting treatment with antibiotics, sample collections were done for culture of urine and blood. Culture and drug susceptibility was identified by use of a method established by the Clinical and Laboratory Standards Institute. Results: A total of 1,814 biopsy procedures were performed in 1,541 patients. For 1,246patients, the procedure was the first biopsy, whereas for 295 patients it was a repeat biopsy. Twenty-one patients (1.36%) were identified as having acute bacterial prostatitis after the biopsy. Fifteen patients (1.2%) had acute prostatitis after the first biopsy,and 6 patients (2.03%) experienced acute prostatitis after a repeat biopsy. Even though the incidence of acute bacterial prostatitis was higher after repeat biopsy than that after the first biopsy, there was no statistically significant intergroup difference in terms of incidence (χ2=1.223, p=0.269). When the collected urine and blood samples were cultured,Escherichia coli was found in samples from 15 patients (71.4%), Klebsiella pneumoniae in 3 patients (14.3%), Enterobacter intermedius in 1 patient (4.8%), E. aerogenes in 1 patient (4.8%), and Pseudomonas aeruginosa in 1 patient (4.8%). A fluoroquinolone-resistant strain was confirmed in 5 cases (23.8%) in total. Three cases of E. coli and 1 case of Klebsiella had extended-spectrum β-lactamase activity. Conclusions: Empirical treatment of acute prostatitis should be done with consideration of geographical prevalence and drug resistance. This study will provide meaningful information for the management of acute prostatitis after transrectal prostate biopsy.

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.

오스트리아 Koralm 터널의 수직구 시공 실드 공법

방준호 한국지반공학회 2006 지반 : 한국지반공학회지 Vol.22 No.11

고분자 광섬유 증폭기 모재 제조

방준호,정찬성,한미진,이창석,최재호,이종호,양승각,이용욱 한국통신학회 2002 한국통신학회 기타 간행물 Vol.2002 No.10

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.

퍼지확률이론과 손상지수를 이용한 지하암반공동에서의 스폴링 발생 평가

방준호,이강현,이인모,Bang, Joon-Ho,Lee, Kang-Hyun,Lee, In-Mo 한국터널지하공간학회 2010 한국터널지하공간학회논문집 Vol.12 No.1

Spalling is a kind of instability phenomenon of surrounding rock around underground openings subjected to high in-situ stress according to the development of extension fractures. Three kinds of spalling criteria have been presented so far; however, all spalling criteria have the range of values so that the fuzziness and vagueness of spalling criterion cannot be avoided. In this study, a new fuzzy probability model is proposed to predict the probability of spalling in a systematic way by using fuzzy probability theory. Many of the underground opening projects worldwide are evaluated with the proposed method. Prediction results expressed as the spalling probability agree well with the in-situ observations. In particular, a new fuzzy probability model considering all three evaluation indices of spalling by adopting weighting factors based on relative reliability among three evaluation indices is able to resolve erroneous prediction of spalling by choosing only one prediction method. Moreover, the more reasonable value of spalling probability could have been obtained by adopting the modified damage index to the newly proposed fuzzy probability model. 스폴링 현상은 높은 현지응력하에서 확장균열의 발달로 암반공동 주변에서 발생하는 파괴형태이다. 기존 연구에 의하면 3가지 스폴링 기준은 범위로 제시되어 있어 기준자체의 애매모호함이 상존하고 있다. 본 연구에서는 퍼지확률이론을 적용한 새로운 스폴링 발생 종합 평가모델을 제안하였고 스폴링 발생현장에 평가모델을 적용한 결과 현장관측결과와 일치하는 결과를 보였으며, 정량적으로 스폴링 발생확률을 산정할 수 있었다. 특히, 3가지 스폴링 평가인자별 상대중요도를 고려한 가중치를 적용함으로써 실제 스폴링이 관측된 현장이 스폴링이 발생하지 않는 것으로 평가되는 오류를 해결하였다. 또한, Martin 등(1999)의 손상지수에 형상계수를 도입한 수정손상지수가 포함된 스폴링 평가인자를 스폴링 발생 종합 평가모델에 적용한 결과 합리적인 스폴링 발생확률을 산정할 수 있었다.

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.

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.