• Journal of the Korean Geotechnical Society
• /
• v.39 no.5
• /
• pp.27-40
• /
• 2023

A pile is a structural element that is used to transfer external loads from superstructures and has been widely utilized in construction fields all over the world. The method of installing a pile into the ground should be selected based on geotechnical conditions, location, site status, environmental factors, and construction costs, among others. It can be divided into two types: direct hammering and preboring. The direct hammering method installs a pile into the bearing layer, such as rock, using a few types of hammer, generating a considerable amount of pile driving-induced vibration. The vibration from pile driving influences adjacent structures and the ground; therefore, quantitatively investigating the effects of vibration is inevitably required. In this study, two-dimensional dynamic numerical modeling and analysis are performed using the finite difference method to investigate the influence on the adjacent slope, including temporary supporting system. Time-dependent loading induced by pile driving is estimated and used in the numerical analysis. Consequently, large surface displacement is estimated due to surface waves and less wave deflection, and refraction at the surface. The total displacement decreases with the increase of the distance from the source. However, lateral displacement at the top of the slope shows a larger value than vertical displacement, and the overall displacement tends to be concentrated near the face of the slope.

• Journal of Environmental Impact Assessment
• /
• v.32 no.5
• /
• pp.291-304
• /
• 2023

Harmful algal blooms (HABs) have become an increasing concern in terms of human health risks as well as aesthetic impairment due to their toxicity. The reduction of water pollutants, especially nutrients from non-point sources in a reservoir watershed, is fundamental for HABs prevention. We investigated the pollutant removal efficiencies of a constructed wetland to evaluate its feasibility as a method for controlling non-point sources located in the Annaecheon stream within the Daecheong Reservoir watershed. The overall removal efficiencies of pollutants were as follows: BOD 14.3%, COD 17.9%, SS 50.0%, T-N 19.0%, and T-P 35.4%. These results indicate that constructed wetlands are effective in controlling pollutants from non-point sources. The seasonal variation in removal efficiency depended on the specific pollutants. The removal efficiencies of BOD, COD, and T-N were stable throughout the year, except during winter, which might have been influenced by lower microorganism activity. In contrast, T-P showed a consistent removal efficiency even during the winter season, suggesting that the wetland can reduce external phosphorus loading to the reservoir. Regarding the effects of pollutant loadings on removal efficiency, the effluent concentrations of all pollutants were significantly decreased compared to those in the influent in case of middle and high loadings. This demonstrates that constructed wetlands can handle high pollutant loads, including the initial runoff during rainfall, to prevent reservoir eutrophication. Despite the various strengths of wetland water purification, there are limitations as passive treatment. Therefore, more case studies should be conducted to suggest optimum operational conditions for constructed wetlands, taking into consideration reservoir-specific characteristics.

• Tuberculosis and Respiratory Diseases
• /
• v.45 no.1
• /
• pp.68-76
• /
• 1998

Background: Patients with centrally recurred bronchogenic carcinoma make a complaint of many symptoms like hemoptysis, cough & dyspnea. At these conditions, the goal of treatment is only to relieve their symptoms. High dose rate brachytherapy(HDR-BT) is the palliative treatment modality of centrally located endobronchial tumor regardless of previous external irradiation(XRT) on the same site in symptomatic patients. Methods: We studied the effects of HDR-BT in 26 patients with symptomatic recurrent lung cancer. Patients(male: 24, mean age: 54yrs)were treated with HDR-BT underwent bronchoscopic placement of $^{192}Ir$ HDR after loading unit(Gammamed$^{(T)}$, Germany) to deliver 500cGY intraluminal irradiation at a depth of 1cm every lwk on 3 occasions. Evaluation at base line and 4wks after HDR brachytherapy included chest X-ray, bronchscopy, symptoms (Standadized Scale for dyspnea,cough,hemoptysis), and Karnofsky performance scale. Results: Endobronchial obstruction was improved in 11/26 patients(37%). Atelectasis in chest X-ray was improved in 5/15 patients(33%). Hemoptysis, dyspnea & cough were improved in 5/10 patients (50%), 5/8 patients (62%) & 10/18 patients (56%) respectively. Karnofsky performance status was changed from 76.4 scores in pretreatment to 77.6 scores after treatment. During HDR-BT, massive hemoptysis (2 patients) and pneumothorax(1 patient) were occurred as complications. Conclusion: We concluded that HDR-BT gave additional benefits for the control of symptoms and general performance and endobronchial obstruction & atelectasis. And HDR-BT will be an additional treatment for the recurrent and endobronchial obstructive lung cancer.