유수실 상부 덮개가 있는 케이슨 방파제의 유공률에 따른 전면벽 작용 파압 비교

오상호,지창환,오영민,장세철,Oh, Sang-Ho,Ji, Chang-Hwan,Oh, Young Min,Jang, Se-Chul 대한토목학회 2013 대한토목학회논문집 Vol.33 No.2

본 연구에서는 유수실 상부 덮개가 있는 케이슨 방파제의 전면벽 유공률 변화에 따라서 전면벽 파압 분포가 어떻게 달라지는지 실험적으로 고찰하였다. 우선 전면벽 유공률이 0인 무공 케이슨에 대해서 파압을 측정하여 이를 Goda(1974)의 파압 분포와 비교하였다. 분석 결과, 계측된 파압분포는 Goda의 파압 공식과 대체로 잘 일치하였으며, 이를 통해서 본 실험에서 파압이 정확하게 측정되었음을 확인하였다. 한편, 유공 케이슨의 경우 전면벽 유공률을 0.2, 0.25, 0.3으로 변화시키면서 실험을 수행하였다. 대부분의 실험 조건에서는 유공률에 따른 전면벽 파압 분포에 차이가 거의 없었던 반면, 비교적 파고 및 주기가 큰 일부 실험파의 경우에는 유공률이 클수록 파압이 근소하게 증가하는 경향이 나타났다. 그러나 전면벽 총파력은 대체로 유공률에 따른 차이가 미미하였다. This study experimentally investigated the change in distribution of wave pressure on the front wall according to the variation of the front wall porosity of the caisson breakwater having the cap of wave chamber. First, the wave pressure for the non-porous caissson corresponding to zero porosity was measured and compared with the pressure formula suggested by Goda(1974). The analysis showed that the measured pressure distribution fairly well agreed with the Goda formula, which confirmed the accurate measurement of wave pressure in the present experiment. In case of the porous caisson, meanwhile, the experiment was performed by varying the front wall porosity as 0.2, 0.25, and 0.3. The wave pressure distribution at the front wall showed little difference according to the porosity for most of the test wave conditions, whereas the pressure slightly increased with the porosity for some test waves whose wave heights and periods were relatively large. However, the difference according to the porsosity was insignificant for the wave force at the front wall.

Alumina dummy 충전재를 이용한 GaN 기반 박막재료의 단면 TEM 시편준비

오상호,최주형,송경,정종만,김진규,유인근,유석재,김영민,Oh, Sang-Ho,Choi, Joo-Hyoung,Song, Kyung,Jeung, Jong-Man,Kim, Jin-Gyu,Yu, In-Keun,Yoo, Suk-Jae,Kim, Young-Min 한국현미경학회 2009 Applied microscopy Vol.39 No.3

Practical difficulties for preparing a good crosssectional specimen of GaN-based materials for transmission electron microscopy have arisen due to large difference of mechanical properties between hard ceramic substrate and soft GaN-layered materials. Uneven polishing, sudden cracking, delamination, and selective sputtering during the conventional wedge polishing technique are often encountered as experimental hindrances. The preparation technique based on Strecker's method can be applied to overcome these difficulties, which eventually leads to mechanically stable TEM samples independent of the mechanical properties of materials. The basic idea is to use hard ceramic dummy filler for embedding the sample of interest into the dummy frame. In this study, we applied this technique into preparing cross-sectional TEM specimen of the GaN-based materials with mechanical instability and demonstrated usefulness of this hard dummy filler method in which the possible modifications of the sample of interest during the preparation must be avoidable. In addition, practical precautions during the preparation were discussed.

유수실 상부 덮개가 유공 케이슨 방파제의 전면벽 및 후면벽 파압에 미치는 영향

오상호,지창환,오영민,장세철,Oh, Sang-Ho,Ji, Chang-Hwan,Oh, Young-Min,Jang, Se-Chul 대한토목학회 2013 대한토목학회논문집 Vol.33 No.6

이 연구에서는 수리모형실험을 통해 유수실 상부 덮개가 유공 케이슨 방파제 전면벽 및 후면벽에서의 파압에 미치는 영향을 고찰하였다. 수리모형실험은 유공 케이슨의 유수실 상부 덮개가 있는 경우 및 없는 경우에 대해서 전면벽 유공률을 변화시키면서 이루어졌다. 유수실 상부가 덮개로 막혀 있을 때에는 모든 실험 조건에서 유의미하게 더 큰 파압이 취득되었으며 따라서 유수실 상부 덮개 존재에 따른 두 벽에서의 계측 파압 차이는 매우 뚜렷하게 나타났다. 그 결과 계측 파압을 적분하여 계산된 전파력의 크기 역시 상부 덮개가 있는 케이슨 방파제의 경우가 더 컸으며, 이 경우 잘 알려진 Takahashi의 파압식에 근거한 파력값을 상회하였다. 한편, 전면벽 유공률에 따라서는 방파제 전면벽 및 후면벽에서 모두 유공률이 클수록 더 큰 파압이 계측되었다. In this study, the effect of wave chamber slab on wave pressure along the first and second wall of the perforated caisson breakwater was investigated by performing physical experiment. The experiment was performed without and with the wave chamber slab of the perforated caisson by varying the front wall porosity. The discrepancy in magnitudes of the measured wave pressure along the both walls of the perforated caisson was apparent according to the existence of the wave chamber slab as significantly greater pressures were acquired for all the test cases when the wave chamber was closed upward by the slab. As a result, the magnitudes of the total wave force calculated by integration of the measured wave pressure also were much larger for the caisson breakwater having the wave chamber slab, exceeding the value based on the well known Takahashi's formula (Takahashi and Shimosako, 1994). With respect to the porosity of the front wall, meanwhile, higher pressures were obtained with a larger porosity, at both the first and second wall of the breakwater.

규칙파 실험에 의한 수중터널의 거동 및 동수역학적 특성 고찰

오상호,박우선,장세철,김동현,Oh, Sang-Ho,Park, Woo Sun,Jang, Se-Chul,Kim, Dong Hyawn 대한토목학회 2013 대한토목학회논문집 Vol.33 No.5

이 연구에서는 2차원 조파수조에서 수리모형실험을 실시하여 수중터널 모형의 수리학적, 구조적 성능을 고찰하였다. 수심 및 부력 대 자중비를 다양하게 변화시킨 조건에서 파고 및 주기가 서로 다른 규칙파를 조파하여 실험을 수행하였다. 실험 자료의 분석을 통해서 연직방향 및 횡방향 동요가 파고 및 주기에 따라 선형적으로 증가함을 확인하였다. 반면에, 회전 운동의 크기는 파고 및 주기가 설계파 정도로 커지지 않으면 별로 크게 나타나지 않았다. 마찬가지로, 계류장력 및 수중터널에 작용하는 파력도 파고 및 주기에 따라 선형적으로 증가하였다. 수심 및 부력 대 자중비의 변화와 관련해서는, 구조적 거동 및 수중터널에 작용하는 파력의 크기 모두 수심 증가 및 부력 대 자중비 감소에 따라서 전체적으로 감소하는 경향이 나타났다. In this study, physical experiments were performed in a two-dimensional wave flume to investigate the hydraulic and structural performance of a SFT model. The experiments were made by generating regular waves of different heights and periods under various conditions of buoyancy to weight ratio (BWR) and water depth as well. Through the analysis of the experimental data, it was clarified that the sway and heave motions of the tunnel body linearly increased with wave height and period. In contrast, the roll motion was rather insignificant unless wave height and period were comparatively large as the design wave. Similarly proportional relationship with respect to wave height and period was obtained in case of the maximum tensile force acting on the tension legs and the wave loads on the tunnel body. Regarding the change of water depth or BWR conditions, generally decreasing trend was obtained according to increase of water depth but decrease of BWR for both of the magnitudes of structural behaviors or wave loadings on the SFT structure.

The clinical practice of NB-UVB in vitiligo

오상호 ( Sang Ho Oh ) 대한피부과학회 2013 대한피부과학회 학술발표대회집 Vol.65 No.2

Vitiligo is a common acquired depigmenting disorder caused by the loss of melanocytes mainly due to immunologic mechanisms. In treating vitiligo, a variety of treatment can be applied, but a lot of time and effort are required before seeing to see remarkable repigmentation. Of various treatment options for vitiligo, phototherapy is widely being used as a first line treatment of generalized vitiligo. Among phototherapy, NB-UVB is now the mainstay of vitiligo treatment; NBUVB showed comparable or superior results to PUVA in vitiligo and psoralen is no longer produced in Korea. Dermatologists can choose two kinds of NBUVB phototherapy devices such as a cabinet-type or an external type depending on distribution, extent and site of lesions. The energy can be irradiated to body by automatically calculating irradiation time by the machine when the wanted value of energy is put entered into the machine. In today`s talk, I will show a video clip on a usage of NBUVB phototherapy unit that will be of a practical help in starting phototherpy. Together I will discuss the appropriate starting energy and dose increment. Maximum treatment energy and treatment sessions, although not yet clearly determined, will also be discussed. Lastly, this talk will include treatment response of NBUVB, factors which affect treatment response and prognosis after stopping NBUVB phototherapy.

테트라포드로 피복된 케이슨에 작용하는 파력 계측 수리실험

오상호(Oh, Sang-Ho),이종인(Lee, Jong-In),김영택(Kim, Young-Taek) 대한토목학회 2019 대한토목학회 학술대회 Vol.2019 No.10

반파 구조물에 의한 월파 저감 효과 분석

오상호(Sang-Ho Oh) 한국해안해양공학회 2016 한국해안해양공학회 논문집 Vol.28 No.1

수리실험을 통해 반파 구조물에 의한 월파 저감 효과를 정량적으로 분석하는 연구를 수행하였다. 원호 호안 및 경사 호안 모형에 대한 월파량을 계측하고 반파 구조물에 의한 월파량 저감 예측식과 비교하였다. 월파량이 비교적 많은 경우(q/√gH³s〉10<SUP>-3</SUP>)에는 예측식과 실험 결과가 대체로 잘 일치하였으나, 월파량이 이보다 적은 경우에는 예측식과 실험의 편차가 크게 나타났다. 이러한 점을 고려하여 반파 구조물에 의한 월파 저감 효과를 보다 잘 예측할 수 있는 산정식을 개발할 필요가 있다. The effect of reducing wave overtopping by use of the wave return wall was quantitatively analyzed based on physical experiments. The overtopping discharge for the arc seawall and the inclined seawall was measured and compared with the predictive formula that estimates reduction of overtopping by the wave return wall. When the overtopping discharge was relatively large (q/√gH³s〉10<SUP>-3</SUP>), the agreement in terms of overtopping reduction rate was fairly good between the prediction and the measurement. For the condition of smaller overtopping than the above criterion, however, the discrepancy was large between the predicted and measured result. In this context, it is required to develop a better formula for estimating reduction of wave overtopping by the wave return wall.

단일 및 이중유수실 유공케이슨 방파제에 작용하는 최대 수평파력 비교

오상호(Oh, Sang-Ho),지창환(Ji, Chang-Hwan),오영민(Oh, Young Min),장세철(Jang, Se-Chul),이달수(Lee, Dal Soo) 한국해안해양공학회 2014 한국해안해양공학회 논문집 Vol.26 No.5

이 연구에서는 단면 수리모형실험을 통해 파의 여러 위상에 따라 단일 및 이중유수실 유공케이슨 방파제의 연직벽에 작용하는 최대 수평파력을 계측하고 그 크기를 서로 비교하였다. 본 실험 자료 분석 결과 이중유수실 케이슨의 유수실 전체 폭이 단일유수실의 폭과 동일한 경우 이중유수실 케이슨에 작용하는 총 수평파력이 평균적으로 9.6% 작은 것으로 나타났다. 이러한 파력 저감 효과는 이중유수실 케이슨 방파제의 유공 전면벽과 무공 후면벽 사이에 위치한 유공 중간벽에서 파 에너지가 소산되기 때문인 것으로 파악되었다. Physical experiments were carried out to measure the wave force on the vertical walls of perforated breakwater considering several phases of a wave acting on the breakwater. The maximum horizontal wave force acting on each vertical wall was compared between single and double chamber caisson breakwater. The experimental data in this study showed that the total horizontal wave force for double chamber caisson was 9.6% smaller on average than that for single chamber caisson when the total chamber width was the same for both caissons. Such reduction of the wave force is due to the dissipation of wave energy at the porous middle wall, which is located between the porous front wall and non-porous rear wall.

Practical aspects of phototherapy in vitiligo and progressive macular hypomelanosis

오상호 ( Sang Ho Oh ) 대한피부과학회 2013 대한피부과학회 학술발표대회집 Vol.65 No.2

Vitiligo is a common acquired depigmenting disorder caused by loss of melanocytes mainly due to immunologic mechanisms. Progressive macular hypomelanosis (PMH) which is characterized by asymptomatic hypopigmented macules located predominantly on the trunk commonly occurs in young woman. Though this condition is still of uncertain etiology, PMH is thought to be induced by skin-lightening factor produced by Propionibacterium acnes (P. acnes) present in the sebaceous ducts of hair follicles. NBUVB phototherapy is widely used as a first line treatment of generalized vitiligo. The purpose of NBUVB treatment in vitiligo is not only for repigmentation and tanning but also for immuneregulation for stopping the spread of vitiligo. In this talk, I will discuss the appropriate starting energy, dose increment, treatment response, and factors that affect treatment response. Currently, only little information on effective treatment for PMH is known. There have been recent reports that NB-UVB therapy is an effective and safe method for use in the treatment of PMH. In addition, as P. acnes is known to be associated with PMH, topical bezoyl peroxide and clindamycin in combination with UVA have been suggested as another treatment option. However, empirically speaking, it is hard to expect effective repigmentation only with topical antibiotics; phototherapy should be preferentially considered for inducing noticeable repigmentation. In this talk, I will share my experiences of using NBUVB for PMN treatment supported by recent review of literature.

이중유수실 케이슨 중간벽에 작용하는 수평파력 계측

오상호(Oh, Sang-Ho),지창환(Ji, Chang-Hwan),오영민(Oh, Young Min),장세철(Jang, Se-Chul) 한국연안방재학회 2014 한국연안방재학회 학술발표대회 논문집 Vol.2014 No.-

이중유수실 케이슨 방파 제 중간벽에 작용하는 최대 수평파력을 계측한 결과 무공 직립벽에 대해 제안된 Goda식에 비해서 20~40% 정도의 크기로 나타났다. 비록 중간벽에 작용하는 파력은 전면벽 또는 후면벽에 비해서 상대적으로 작지만, 추가 적인 파랑에너지 소산을 발생시키는 효과가 있기 때문에 유수실 폭이 동일한 단일유수실 케이슨에 비해서 이중 유수실 케이슨에 작용하는 파력이 더 작은 것으로 나타났다.