Design Guidelines of Elevated Buildings for Antarctic Environment (Ⅰ)-Wind Load

D.H.Kim(金東爀),K.C.S. Kwok,H.F. Rohde 한국해양공학회 1990 韓國海洋工學會誌 Vol.4 No.2

南極建物은 南極의 거센 바람 및 이에 수반되는 積雪現象을 피하기 위해 땅에서 띄우는 高床式 및 地下에 設置하는, 두가지의 形態를 취하고 있다. 高床式의 경우 建物밑으로 바람을 通하게 함으로써 積雪現象을 피하는데 效果的이기는 하나 南極의 거센 바람에 對應하기 위하여 構造的인 問題를 해결해야 하는 취약점을 지니고 있다. 本 硏究는 境界層難流風洞을 利用하여 高床式 南極建物에 가해지는 風何重을 把握함으로서 南極建物의 design guideline을 提示하였다.

A review of two theories of motion sickness and their implications for tall building motion sway

D. Walton,S. Lamb,Kenny C.S. Kwok 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.6

Low-frequency building vibration is known to induce symptoms of motion sickness in some occupants. This paper examines how the adoption of a theory of motion sickness, in conjunction with a dose-response model might inform the real-world problem of managing and designing standards for tall building motion sway. Building designers require an understanding of human responses to low-dosage motion that is not adequately considered by research into motion sickness. The traditional framework of Sensory Conflict Theory is contrasted with Postural Instability Theory. The most severe responses to motion (i.e., vomiting) are not experienced by occupants of wind-excited buildings. It is predicted that typical response sets to low-dosage motion (sleepiness and fatigue), which has not previously been measured in occupants of tall-buildings, are experienced by building occupants. These low-dose symptoms may either be masked from observation by the activity of occupants or misattributed to the demands of a typical working day. An investigation of the real-world relationship between building motion and the observation of low-dose motion sickness symptoms and a degradation of workplace performance would quantify these effects and reveal whether a greater focus on designing for occupant comfort is needed.

Simulation and Analysing Methods of Snowdrifting around an Elevated Building in Antarctica

D. H. Kim(金東爀),K. C. S. Kwok(鄭中秀),H. F. Rohde 한국해양공학회 1989 韓國海洋工學會誌 Vol.3 No.2

南極의 雪堆現象을 模擬實驗하기 위하여 閉銷式 大氣境界層亂流風洞을 濠洲 시드니大學 土木工學科에 制作 設置하였다. 鐵鋼과 100㎜ 높이의 矩形판자 및 촘촘한 양탄자 등의 實驗要素를 使用하여 境界層剪斷亂流를 誘導發生시켰다. 誘導發生된 亂流는 濠洲領 南極領土의 海岸地域에 부는 亂流와 비슷한 類型을 띄었다. 자연눈에 代替할 物質을 찾기 위하여 몇몇 種類의 가루를 使用하였으나 중탄산 나트륨이 가장 適合한 것임이 判明되었다. 南極建物모델 주위에 實驗을 通해 쌓인 눈의 形態는 미쑤하시(1982)의 現地調査結果와 比較되었다. Moire fringe 카메라를 使用하여 쌓인 눈의 形態로 부터 等高線무늬를 型象化시켰으며 image processing unit을 利用하여 等高線무늬를 捕捉한 후 等高線 分析 software를 利用, 눈의 形態와 量을 分析하였다.

A review of two theories of motion sickness and their implications for tall building motion sway

Walton, D.,Lamb, S.,Kwok, Kenny C.S. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.6

Low-frequency building vibration is known to induce symptoms of motion sickness in some occupants. This paper examines how the adoption of a theory of motion sickness, in conjunction with a dose-response model might inform the real-world problem of managing and designing standards for tall building motion sway. Building designers require an understanding of human responses to low-dosage motion that is not adequately considered by research into motion sickness. The traditional framework of Sensory Conflict Theory is contrasted with Postural Instability Theory. The most severe responses to motion (i.e., vomiting) are not experienced by occupants of wind-excited buildings. It is predicted that typical response sets to low-dosage motion (sleepiness and fatigue), which has not previously been measured in occupants of tall-buildings, are experienced by building occupants. These low-dose symptoms may either be masked from observation by the activity of occupants or misattributed to the demands of a typical working day. An investigation of the real-world relationship between building motion and the observation of low-dose motion sickness symptoms and a degradation of workplace performance would quantify these effects and reveal whether a greater focus on designing for occupant comfort is needed.

Effect of low frequency motion on the performance of a dynamic manual tracking task

Melissa D. Burton,Kenny C.S. Kwok,Peter A. Hitchcock 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.6

The assessment of wind-induced motion plays an important role in the development and design of the majority of today’s structures that push the limits of engineering knowledge. A vital part of the design is the prediction of wind-induced tall building motion and the assessment of its effects on occupant comfort. Little of the research that has led to the development of the various international standards for occupant comfort criteria have considered the effects of the low-frequency motion on task performance and interference with building occupants’ daily activities. It has only recently become more widely recognized that it is no longer reasonable to assume that the level of motion that a tall building undergoes in a windstorm will fall below an occupants’ level of perception and little is known about how this motion perception could also impact on task performance. Experimental research was conducted to evaluate the performance of individuals engaged in a manual tracking task while subjected to low level vibration in the frequency range of 0.125 Hz-0.50 Hz. The investigations were carried out under narrowband random vibration with accelerations ranging from 2 milli-g to 30 milli-g (where 1 milli-g = 0.0098 m/s^2) and included a control condition. The frequencies and accelerations simulated are representative of the level of motion expected to occur in a tall building (heights in the range of 100 m -350 m) once every few months to once every few years. Performance of the test subjects with and without vibration was determined for 15 separate test conditions and evaluated in terms of time taken to complete a task and accuracy per trial. Overall, the performance under the vibration conditions did not vary significantly from that of the control condition, nor was there a statistically significant degradation or improvement trend in performance ability as a function of increasing frequency or acceleration.

Switching profiles in a population-based cohort of rheumatoid arthritis receiving biologic therapy: results from the KOBIO registry

Park, D. J.,Choi, S. J.,Shin, K.,Kim, H. A.,Park, Y. B.,Kang, S. W.,Kwok, S. K.,Kim, S. K.,Nam, E. J.,Sung, Y. K. Springer Science + Business Media 2017 CLINICAL RHEUMATOLOGY Vol.36 No.5

<P>Despite improved quality of care for rheumatoid arthritis (RA) patients, many still experience treatment failure with a biologic agent and eventually switch to another biologic agent. We investigated patterns of biologic treatment and reasons for switching biologics in patients with RA. Patients with RA who had started on a biologic agent or had switched to another biologic agent were identified from the prospective observational Korean nationwide Biologics (KOBIO) registry. The KOBIO registry contained 1184 patients with RA at the time of initiation or switching of biologic agents. Patients were categorized according to the chronological order of the introduction of biologic agents, and reasons for switching biologics were also evaluated. Of the 1184 patients with RA, 801 started with their first biologic agent, 228 were first-time switchers, and 89 were second-time or more switchers. Second-time or more switchers had lower rheumatoid factor and anti-CCP positivity, and higher disease activity scores at the time of enrollment than the other groups. Among these patients, tocilizumab was the most commonly prescribed biologic agent, followed by adalimumab and etanercept. The most common reason for switching biologics was inefficacy, followed by adverse events, including infusion reactions, infections, and skin eruptions. Furthermore, the proportion of inefficacy, as a reason for switching, was significantly higher with respect to switching between biologics with different mechanisms of action than between biologics with similar mechanisms. In this registry, we showed diverse prescribing patterns and differing baseline profiles based on the chronological order of biologic agents.</P>

Wind-Induced Motion of Tall Buildings: Designing for Occupant Comfort

Burton, M.D.,Kwok, K.C.S.,Abdelrazaq, A. Council on Tall Building and Urban Habitat Korea 2015 International journal of high-rise buildings Vol.4 No.1

A team of researchers and practitioners were recently assembled to prepare a monograph on "Wind-Induced Motion of Tall Buildings: Designing for Habitability". This monograph presents a state-of-the-art report of occupant response to wind-induced building motion and acceptability criteria for wind-excited tall buildings. It provides background information on a range of pertinent subjects, including: ${\bullet}$ Physiological, psychological and behavioural traits of occupant response to wind-induced building motion; ${\bullet}$ A summary of investigations and findings of human response to real and simulated building motions based on field studies and motion simulator experiments; ${\bullet}$ A review of serviceability criteria to assess the acceptability of wind-induced building motion adopted by international and country-based standards organizations; ${\bullet}$ General acceptance guidelines of occupant response to wind-induced building motion based on peak acceleration thresholds; and ${\bullet}$ Mitigation strategies to reduce wind-induced building motion through structural optimization, aerodynamic treatment and vibration dissipation/absorption. This monograph is to be published by the American Society of Civil Engineers (ASCE) and equips building owners and tall building design professionals with a better understanding of the complex nature of occupant response to and acceptability of wind-induced building motion. This paper is a brief summary of the works reported in the monograph.

Effect of low frequency motion on the performance of a dynamic manual tracking task

Burton, Melissa D.,Kwok, Kenny C.S.,Hitchcock, Peter A. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.6

The assessment of wind-induced motion plays an important role in the development and design of the majority of today's structures that push the limits of engineering knowledge. A vital part of the design is the prediction of wind-induced tall building motion and the assessment of its effects on occupant comfort. Little of the research that has led to the development of the various international standards for occupant comfort criteria have considered the effects of the low-frequency motion on task performance and interference with building occupants' daily activities. It has only recently become more widely recognized that it is no longer reasonable to assume that the level of motion that a tall building undergoes in a windstorm will fall below an occupants' level of perception and little is known about how this motion perception could also impact on task performance. Experimental research was conducted to evaluate the performance of individuals engaged in a manual tracking task while subjected to low level vibration in the frequency range of 0.125 Hz-0.50 Hz. The investigations were carried out under narrow-band random vibration with accelerations ranging from 2 milli-g to 30 milli-g (where 1 milli-g = 0.0098 $m/s^2$) and included a control condition. The frequencies and accelerations simulated are representative of the level of motion expected to occur in a tall building (heights in the range of 100 m -350 m) once every few months to once every few years. Performance of the test subjects with and without vibration was determined for 15 separate test conditions and evaluated in terms of time taken to complete a task and accuracy per trial. Overall, the performance under the vibration conditions did not vary significantly from that of the control condition, nor was there a statistically significant degradation or improvement trend in performance ability as a function of increasing frequency or acceleration.

Aspects of the dynamic wind-induced response of structures and codification

K. C. S. Kwok,Yukio Tamura,Ahsan Kareem,Giovanni Solari,J. D. Holmes,W. H. Melbourne 한국풍공학회 2005 Wind and Structures, An International Journal (WAS Vol.8 No.4

A Nationwide Analysis Evaluating the Safety of Using Acellular Dermal Matrix with Tissue Expander-Based Breast Reconstruction

Jessica Luo,Whitney D. Moss,Giovanna R. Pires,Irfan A. Rhemtulla,Megan Rosales,Gregory J. Stoddard,Jayant P. Agarwal,Alvin C. Kwok 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.6

Background In March 2021, the United States Food and Drug Administration (FDA) safety communication cautioned against the use of acellular dermal matrix (ADM) products in breast reconstruction and reiterated that the FDA does not approve ADM use in breast surgery. This study aims to assess the safety of ADM use in breast reconstruction. Methods Women who underwent ADM and non-ADM assisted tissue expander (TE)- based breast reconstruction were identified using the National Surgical Quality Improvement Program database (2012–2019). Trends of ADM use over time, and 30-day outcomes of surgical site infection (SSI), dehiscence, and unplanned reoperation were assessed. Results Of the 49,049 TE-based breast reconstructive cases, 42.4% were ADM assisted and 57.6% non-ADM assisted. From 2012 to 2019, the use of ADM increased from 26.1 to 55.6% (relative risk [RR] ¼1.10; p<0.01). Higher rates of SSI (3.9 vs. 3.4%; p¼0.003) and reoperation (7.4 vs. 6.0%; p<0.001) were seen in the ADM cohort. There was no significant difference seen in dehiscence rates (0.7 vs. 0.7%; p¼0.73). The most common reoperation within 30 days for the ADM group (17.6%) was removal of TE without insertion of implant (current procedural terminology: 11,971). ADM-assisted breast reconstruction was associated with increased relative risk of SSI by 10% (RR¼1.10, confidence interval [CI]: 1.01–1.21; p¼0.03) and reoperation by 15% (RR¼1.15, CI: 1.08–1.23; p<0.001). Conclusions ADM-assisted breast reconstruction more than doubled from 2012 to 2019. There are statistically higher complication rates of SSI (0.5%) and reoperation (1.4%) with ADM use in TE-based breast reconstruction, suggesting that reconstruction without ADM is safe when comparing immediate postoperative outcomes.