이음면 이격이 확장형 단부판 이음부 성능에 미치는 영향에 대한 실험적 연구

김철환,이명재,김희동,김사빈,Kim, Cheol Hwan,Lee, Myung Jae,Kim, Hee Dong,Kim, Sa Bin 한국강구조학회 2016 韓國鋼構造學會 論文集 Vol.28 No.6

This study is experimental research for the effect of gap at the end plate on the performance of extended end-plate type splice. For this research, simple beam type specimens by using extended end-plate type splice are planned. Main variables are the initial gap between end-plates, the installation of finger shim plate before the installation of high tension bolts, the final gap between end-plates, and the installation of finger shim plate after the installation of high tension bolts. The static loading tests results show that the maximum bending strength of splice is not dependent on the gap, but the vertical displacement, initial stiffness and elastic stiffness are affected by the gap. In addition to that, the possibility of brittle fracture is increased when the torque of high tension bolt is used to control the gap. Thus, careful consideration is needed in this case. 두본 연구는 실험적인 방법을 통하여 단부판 이음부의 이음면에서 초기 오차로 발생하는 이격이 이음부의 내력 및 거동에 미치는 영향을 평가한 연구이다. 이를 위하여 총 5가지의 단순보형 실험체를 확장형 단부판 이음부를 이용 계획하였고 주요 변수로는 이음면 초기 이격(gap) 여부, 고력볼트 채결 전 끼움판(finger shim plate) 설치 유무, 고력볼트 체결 후 이음면 이격, 고력볼트 채결 후 끼움판 삽입 여부를 적용하였다. 정적가력실험 결과 이음판의 이격은 이음부의 최대휨강도에 미치는 영향은 제한적이나 수직변형과 초기 및 탄성강성에는 영향을 미치는 것으로 나타났으며, 이격을 제어하기 위해 고력볼트 장력을 이용할 경우 고력볼트의 취성파괴 우려도 있는 것으로 나타나서 이들에 대한 충분한 고려가 필요할 것으로 판단된다.

경량전철 사업의 SE 적용을 위한 비용 추정 모델 연구

김철환,한명덕,이재홍,이창영,Kim, Chul Whan,Han, Myeong-Deok,Lee, Jae Hong,Lee, Chang Young 한국시스템엔지니어링학회 2012 시스템엔지니어링학술지 Vol.8 No.1

This research aims to propose a model to estimate the appropriate SE Cost rate to the total project cost when systems engineering applied to light rail transit project. In this research an investment cost estimation model is proposed with reference to COSYSMO (Constructive System Engineering Cost Model). This model includes four input factors such as requirement numbers, interface numbers, algorithm numbers, and scenario numbers. When 2600 requirement numbers are considered on a proposal document with 350 pages in a light rail transit specification of 500 billion~trillion won scale, COSYSMO demo version estimates 42.5 billion won of SE cost (about 5% of total project cost or about 10% of E&M cost).

전외측대퇴유리피판 (Anterolateral Thigh Free Flap)을 이용한 구강안면부 결손의 재건

김철환,방대연,황승연,Kim, Chul-Hwan,Bhang, Dae-Yeon,Hwang, Seung-Yeon 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6

Recently, the anterolateral thigh(ALT) flap, based on the septocutaneous vessels or musculocutaneous perforators from the descending branch of the lateral circumflex femoral artery has gained popularity in head and neck soft-tissue reconstruction. It has some advantages in free-flap surgery with respect to the radial forearm free flap, such as low donor site morbidity, availability of different tissues with large amounts of skin, adaptability as a sensate or flow-through flap (with the possibility of harvesting a long pedicle with a suitable vessel diameter). Moreover, the thickness of the flap is adjustable until the subdermal fat level, allowing it to be used as a thin or ultrathin flap. This clinical cases are ALT free flap reconstructions without functional impairment of the donor limbs (transitory and permanent) based on anastomosis with superficial temporal arteries and veins in patient of huge resection defect on face, lip and tongue.

미국의 무기체계 획득과정과 정책(1)

김철환,Kim, Cheol-Hwan 한국방위산업진흥회 1993 國防과 技術 Vol.- No.175

요즈음 논란이 일고있는 율곡사업등으로 해서 국방부나 각 군에서 혼란을 겪고 있는 "무기체계 획득과정 쇄신"에 도움이 되었으면 해서 미국의 무기체계 획득과정과 정책을 소개합니다 이번 호에 게재된 내용과, 93/10월호에는 –의사결정 지원체계 및 검토과정 –회기득사업요약서/사업계획서 –획득 전문화 제도(DAWIA) –무기체계 획득 및 군수지원 전산화(CALS) –획득정책 발전방향 순으로 계속해서 연재됩니다

Refrigerant distribution in an evaporator having a horizontal header and horizontal mini-channel tubes

김철환,NAE-HYUN KIM 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

In this study, we investigated the R-1234yf distribution from a header into minichannel tubes located in a horizontal plane, which may be of importance for cooling of an electric vehicle battery. Especially, the focus was concentrated on the effect of number of branch tubes on the two-phase distribution. The tests were conducted for the mass flux from 49 to 147 kg/m 2 s and inlet quality from 0.2 to 0.8. The effect of heat exchanger inclination was also investigated. The results showed that the flow distribution worsened as the number of branch tube increased. Between the normal and the parallel inlet configuration, the normal inlet yielded a better distribution, probably due to the smaller number of branch tubes. The flow distribution was mainly governed by the balance of relating forces-momentum and gravitational. Thus, a poor distribution was obtained for a tilted case, where the momentum and the gravitational forces were assisting. The data showed that a vapor quality was always beneficial to the distribution. However, the effect of mass flux was case-dependent. For the horizontal case, the mass flux pushed the flow downstream, and worsened the distribution. For the tilted case, the mass flux assisted or opposed the gravity, yielding a better distribution.

경량전철사업의 시스템엔지니어링 적용 실태분석 연구

김철환,한명덕,이재홍,Kim, Chul Whan,Han, Myeung-Duk,Lee, Jae Hong 한국시스템엔지니어링학회 2012 시스템엔지니어링학술지 Vol.8 No.2

This paper aims to analyze the result of SE Process Implementation on Light Rail Transit(LRT) Project. Currently the Light Rail Transit Project of Korea applies SE to the intermediate phase, that is, E&M phase which is a manufacturing and designing procedure. More seriously, the application effect of SE is not remarkable because it applies to some specific engineering fields like RAMS and it depends on superficial consulting of foreign companies with low SE support capability and investment capital. This study points out that the "Requirement Analysis" and "System Alternative Review" has not been conducted from the initial phase (basic plan and basic design) of the LRT projects. Several projects indicate that the amount of investments for SE activities through the Korea LRT project is relatively very small in comparison with the global capital which is about 10% of total project budget. Furthermore, Korea LRT projects have very few SE professionals and weak SE organization with no government directions and guide book for the efficient implementation of SE for the LRT projects.

도로 주변지역의 소음환경 개선방법

김철환,Kim, Chul-Hwan 대한환경공학회 2008 대한환경공학회지 Vol.30 No.6

악간고정이 호흡기능에 미치는 영향에 대한 임상적 연구

김철환,김미숙,Kim, Chul-Hwan,Kim, Mi-Suk 대한구강악안면외과학회 1999 대한구강악안면외과학회지 Vol.25 No.4

Intermaxillary fixation is routine procedure to oral and maxillofacial area in jaw bone fracture, surgical correction of jaw deformity, osseus reconstruction of jaw. After transoral surgery, accompanied by intermaxillary fixation, dysphagia or airway obstruction may be followed due to blood clot, vomitus, or laryngeal spasm resulting from irritation by blood or secretions. Lingual or pharyngeal edema is other contributing factors of airway obstruction. In addition, intermaxillary fixation itself may cause obstruction of airway. In this study, pulmonary function test and arterial blood gas analysis were evaluated before and after intermaxillary fixation in 30 patients suffered from mandibular fractures. Comparative analysis was performed by estimated values. The results were as followed. 1. The spirometric values of FEV1, FEV1/FVC and FEF25-75% without intermaxillary fixation were reduced from 97.57%, 85.1%, 98.3,% to 71.7%, 66.5%, 61.2% with intermaxillary fixation, indicating the presence of obstructive pulmonary impairment. 2. Spirometric value of MVV, as the most influencing value of sensitive to extrapulmonary factors, was changed from 84.5% to 46.48%. 3. After intermaxillary fixation, the spirometric value of FVC, as indicator of restrictive pattern of pulmonary function, was not reduced significantly as measured from 94.47% to 89.97%. 4. $O_2$ saturation of arterial blood gas analysis without intermaxillary fixation was 97.86%. While intermaxillary fixation, $O_2$ saturation was 97.47%. The results indicate that careful airway management is mandatory undergoing intermaxillary fixation of various oral and maxillofacial surgery.

단층라멜라 돔의 시공 중 서포트 위치에 따른 좌굴특성

김철환,석창목,정환목,Kim, Cheol-Hwan,Suk, Chang-Mok,Jung, Hwan-Mok 한국공간구조학회 2010 한국공간구조학회지 Vol.10 No.4

대공간 구조형식을 갖는 단층 래티스 돔은 역학성, 가능성, 심미성 등을 갖는 구조물로서 그 용도가 점점 확대되고 있다. 단층 래티스 돔의 골조 격자 패턴은 무수히 존재하며, 그 대표적인 패턴에는 삼각형, 사각형, 육각형, 라멜라형, 리브형 등이 있다. 대공간 구조물의 경우, 일반구조물과 달리 재래적인 공법으로 지붕 골조를 시공할 경우 많은 가설재가 소요됨으로 시공비 증가가 예상된다. 따라서 대공간 구조물의 지붕 골조 설치는 특수 Erection 공법에 의하는 것이 일반적이며, 그 중 지상에서 지붕골조를 설치 후 jack-up 서포트에 의해 골조를 인양하는 Step-Up 공법을 적용할 경우 공기와 공비의 대폭적인 절감이 예상된다. 따라서 본 논문의 목적은 Step-Up 공법에 의해 단층라멜라 돔의 지붕골조를 시공할 경우, 인양 중 가설 서포트 개수와 위치에 따른 좌굴특성을 검토하는 것이다. 연구 결과 서포트 개수 및 위치에 따른 단층라멜라 돔의 다양한 좌굴 특성에 관한 실무자를 위한 기초적인 자료를 얻을 수 있었다. Single layer latticed domes which have a mechanics property, a functional property, a aesthetic property and so on, occupies one part of long span space structures and after this, the using parts will be extended. The frame network pattern of single-layer latticed domes can be infinitely taken into account. The typical network patterns are triangular, square, hexagon, lamella and rib etc. It would take long time and cost too much to erect large roof structures with traditional erection techniques due to require of large number of temporary bracing and supports. The erection of large roof structures requires special techniques. As one of these special techniques is the Step-Up election method that utilizes jack-up supports and this will extremely saves time and cost to erect large roof structures. The objective of this study is to analysis the buckling characteristics of single-layer lamella domes according to the support number and position. From the result of this study, we obtained the fundamental data for the structural engineers who design the temporary support of large roof structures.

RC-S 복합보의 역학적 특성에 관한 실험적 연구

김철환,채원탁,Kim, Cheol Hwan,Chae, Won Tak 한국강구조학회 2002 韓國鋼構造學會 論文集 Vol.10 No.3

본 연구에서는 단부 철근콘크리트구조와 중앙부 철골구조로 이루어진 복합구조 보를 대상으로 내력 및 강성, 변형능력을 평가하기 위해 반복재하 실험을 행하였다. 주된 실험변수는 철근콘크리트와 철골보의 이종구조 이음부부의 응력전달을 위해 철골보에 접합되는 철근의 개수와 단부 콘크리트를 구속하여 강성을 상승시킬 목적으로 설치되는 부착판의 설치유무이다. 실험결과 모든 실험체가 방추형의 이력 거동을 나타내며 안정된 거동을 하였으며, 내력에 있어서는 부착판 설치 실험체의 경우가 기본형 실험체 보다 높게 나타났다. 또한, 강성에 있어서도 단부에 부착판을 설치한 실험체가 설치하지 않은 실험체에 비하여 보다 높게 나타났으며, 모든 실험체가 최대 내력시의 부재각이 0.03rad. 이상의 변형능력을 나타내고 있다. The beam of composite structure composed of the RC structure in the end part and steel structure in the central palt were investigated during cyclic loading, in order to evaluate strength, stiffness, and deformational capacity. The parameters used in this study include the amount of reinforced steel bar between the steel beam and RC structure and the existence of the sticking plate. Test results showed that all specimens had stabilized hysteresis loops. Likewise, the specimens with sticking plate had higher load-carrying capacity compared with the one without it. In addition, the stiffness of the composite structure was higher than the steel structure. All specimens also showed good rotational capacity.