• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.1
• /
• pp.38-44
• /
• 2007

Using the mathematical model suggested by Bennet et al.(1992), the reflection and transmission coefficients by a circular pile breakwater has been investigated in the framework of potential theory. Flow separation due to sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of exact energy loss coefficient is critical to enhance the reliability of mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code. The energy loss coefficient can be obtained from the pressure difference between upstream and downstream. Energy loss coefficient is the function of porosity and the relation equation between them is suggested throughout the curve fitting processing. To validated the suggested relation, comparison between the analytical results and the experimental results is made for four different porosities with good agreement.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.1
• /
• pp.1-9
• /
• 2018

In present study, we suggested the quasi-linear model that linearizes the quadratic drag representing the energy loss across the porous plate. The quasi-linear model was solved by Boundary Element Method (BEM) for development of the porous wave absorber suitable for 2-D wave tank. The drag coefficient at the porous plate was newly obtained through comparison of experimental results. It is found that the porous wave absorber with porosity 0.1, submergence depth d/h = 0.1, and inclined angle $10^{\circ}{\leq}{\theta}{\leq}20^{\circ}$ shows the effective wave absorption. Using the developed quasi-linear numerical model, the optimal design of various types of a porous wave absorber will be applied.

• Journal of Korean Society on Water Environment
• /
• v.22 no.3
• /
• pp.513-520
• /
• 2006

The effect of chlorination on disinfection byproducts (DBPs) production from bloom-forming freshwater algae including 7 strains of cyanobacteria and 6 strains of diatoms was investigated. The release and degradation of hepatotoxin (microcystins) by the chlorination on Microcystis under differential condition of the chlorination time and dose were also investigated. The disinfection byproducts formation potentials (DBPFP) of cyanobacterial species and diatoms were ranged from 0.017 to $0.070{\mu}mol\;DBPs/mg$ C and from 0.129 to $0.708{\mu}mol\;DBPs/mg$ C respectively. Among three major groups of DBPs, haloacetonitrils (HANs) was major product in most test strains except Aphanizomenon sp. and Oscillatoria sp. Haloacetic acids (HAAs) was less than 5 % of total DBPs. Chloroform and dichloroacetonitril (DCAN) were dominant compounds in trihalomethanes (THMs) and HANs respectively. After 4 hours chlorination of toxic Microcystis aeruginosa under the dose range of 0.5 to $10mg\;Cl_2/L$, the concentration of intracellular microcystins decreased, but dissolved dissolved microcystins concentration increased with the treatment of more than $3mg\;Cl_2/L$. However the total amount of microcystins was almost constant even at $10mg\;Cl_2/L$ of chlorination. To conclude, our results indicate that the chlorination causes algal cell lysis and release of intracellular microcystins in the intact form to surrounding waters.

• Membrane Journal
• /
• v.23 no.1
• /
• pp.24-44
• /
• 2013

The MBR technology has evolved rapidly over the past two decades with significant gains in performance and reliability, and reductions in costs. Membrane bioreactors (MBR) technology is widely recognised as offering a key option for enhanced wastewater treatment or reuse. The objective of this paper is then to critically review the remarkable achievement on the research and commercial applications of membrane bioreactor (MBR) technology and to present current and potential MBR markets on a global scope. This brief review of the technology incorporates five key aspects : 1) evolution of MBR practice, 2) the commercial technologies of MBRs, 3) the largest MBR installations globally (e.g. > $10,000m^3/day$), 4) MBR market growth, and 5) directions for future research. Finally, the development directions of economical, environmental and technical aspects in MBRs; 1) investment costs; 2) effluent water quality; 3) membrane materials and modules; 4) MBR equipment and treatment process; 5) operating costs (higher energy & chemical consumption); and 6) sustainability such as anaerobic MBRs in the coming years were addressed.

• Fire Science and Engineering
• /
• v.29 no.1
• /
• pp.60-66
• /
• 2015

The present study was aimed to analyze enclosure integrity test, which is the performance experiment of soaking time, in a fire zone equipped with gaseous extinguishing system in an effort to find understand the effect of precaution factors upon the success of fire extinguishment. To achieve the goal of this study, it divided the fire zones of internal and external power plants into ones taking precaution measures and not taking them and then enclosure integrity test was given respectively. Therefore, this study examined the success rate if the test according to the presence and absence of the precaution measure and confirmed the failure factors, designed concentration soaking time and proportion of leakage area to total volume area by type of gaseous extinguishing system and rooms. Precaution measures were applied to the fire zones without them to confirm the increase of the success rate of enclosure integrity test. By doing so, it was found that reduced number of experiments caused by failure led to cost saving.

• Journal of the Korean Solar Energy Society
• /
• v.35 no.1
• /
• pp.9-19
• /
• 2015

Pyranometer have many uncertainty factors (sensitivity function, thermal offset, other spectral effect, geometric, environment, and equipment etc.) than pyrheliometer. The solution for most of the uncertainty factors have been researched, but the problem for thermal offset is being continued research so far. Under the clear sky, due to the thermal offset of pyranometer, the diffuse and global radiation have been negative value for the nighttime and lower value for the daytime, respectively. In order to understand the uncertainty of the thermal offset effect, solar radiation are observed and analyzed using Ji and Tsay method and data from modified pyranometer. As a result of performing temperature correction using the modified pyranometer, the slope (dome factor; k) and intercept ($r_0$) from a linear regression method are 0.064 and $3.457g{\cdot}m^{-2}{\cdot}k^{-1}$, respectively. And the solar radiation is decreased significantly due to the effect of thermal offset during nighttime. The solar radiation from modified pyranometer increased approximately 8% higher than its observed by general pyranometer during daytime. By the way, these results did not generalize because its result is for only single case in clear sky. Accordingly, it is to required for accurate results obtained by the various cases (clear, cloudy and rainy) with longterm observations.

• Korean Journal of Bronchoesophagology
• /
• v.15 no.1
• /
• pp.41-49
• /
• 2009

Background and Objectives : Proton pump inhibitors(PPIs) improve the symptoms of laryngopharyngeal reflux(LPR). But there is little reports about the changes of each items in reflux symptom index (RSI) and reflux finding score (RFS) after PPIstreatment. The purpose of this study is to analyze the changes of pre- and post-treatment score in each RSI and RFS items after 8 weeks medication with proton pump inhibitors in laryngopharyngeal reflux patients. Methods : Prospective study. Among the patients who had visited the department of otolaryngology from January 2007 to December 2008, 91 patients who had shown scores greater than 13 on the RSI and/or 7 on the RFS were studied. All patients received PPIs once daily before breakfast for 8 weeks. RSI and RFS were assessed at initial, four weeks and eight weeks after medication. Result: All RSI items were improved (p < 0.05). The globus sense followed by throat clearing, heartburns and hoarseness showed high initial RSI score than other items. And globus sense, throat clearing, hoarseness and heartburn were improved significantly more than others items. But only posterior commissure hypertrophy of RFS was improved significantly more than others items. Conclusion: Empiric PPIs therapy reduced the RSI scores and more effective for symptoms such as globus sense, throat clearing, hoarseness and heartburn among suspected LPR patients. In RFS, only posterior commissure hypertrophy has improved significantly. However, the changes of each categories of RFS were minimal (average: 0.16), therefore clinical significance is restricted in RFS.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1393-1406
• /
• 2018

In this study, three parameters (Pressure ($X_1$), Airflow rate ($X_2$), Operation time ($X_3$)) were experimentally designed and the predicted model and optimal conditions were established by using the terminal rise velocity of the microbubbles as the response value. The polynomial regression analysis showed that the optimum value for the terminal rise velocity at the Pressure ($X_1$) of 4.5 bar, Airflow rate ($X_2$) of 3.3 L/min and Operation time ($X_3$) of 2.2 min was 5.14 cm/min ($85.7{\mu}m/sec$). Also, the highest microbubble diameter size distribution in the range of 2 to $5{\mu}m$ and 25 to $50{\mu}m$ was confirmed by using a laser particle counting apparatus.

• Journal of Digital Convergence
• /
• v.17 no.1
• /
• pp.295-300
• /
• 2019

Modern society is the era of convergence, and storytelling requires the necessity of storytelling in which two types of data types, emotional stories and information, are fused. Particularly, in the case of VR contents, the user must directly participate in the content and select the information through the process of freely searching $360^{\circ}$ space, so that the user can interact with the content immediately. Therefore, there is a limit to access to the existing storytelling method, and it is considered that the implementation of 'convergent storytelling' that meets two areas of sensitivity and information is considered to be an urgent genre. In this paper, we focus on the spatial characteristics of VR contents, and then, as a way to effectively implement 'convergent storytelling' in VR contents, We propose a custom system by organizing the type into a circle structure. Based on this, it is expected that the technology will be developed into a research of a personalized system that meets two areas of emotion and information by utilizing the context recognition process for VR content and interaction in the fourth industrial revolution era.

• Journal of Sasang Constitutional Medicine
• /
• v.32 no.4
• /
• pp.29-44
• /
• 2020

Objectives We surveyed clinical status of Sasang Constitutional Medicine (SCM) for preparation of adaptation of Clinical Practice Guidelines for Sasang Constitutional Symptomatology. Methods We emailed Google survey form to Doctors of Korean Medicine registered the Association of Korean Medicine on 10/13/2020 and 10/21/2020 and closed survey 10/23/2020. We got a data of 654 cases, removed a case of error, analyzed data of 620 responses by frequency analysis Results and Conclusions Out of 620 respondents, 499 have answered that they refer to or make use of SCM. SCM is mainly applied in the field of treatments using Herbal Medicine. Doctors of Korean Medicine participated in survey of SCM, they think Diseases of digestive system are the most effectively treated by the methods of SCM. Sasang Constitutional Symptomatology most frequently observed are Soeumin Congestive Hyperpsychotic symptomatology, Soyangin Chest-Heat congested Symptomatology, Taeeumin Liver Heat-based Interior Heat disease. The diseases that are mainly applied by SCM are 'Diseases of digestive system' for Soeumin, 'Diseases of digestive system' for Soyangin, 'Diseases of respiratory system' for Taeeumin and 'not applicable' for Taeyangin. The important diagnostic methods of SCM are Inspection-listening and smelling examination-Inquiry-Palpation and survey. In the majority of cases, Prescription of Herbal medicine is used by adding or subtracting some herbal medicine from the original prescription suggested in the oriental medical classics and Saam acupuncture method is the most frequently used for the acupuncture therapy. Diet therapy is the most frequently used for the method of prevention and care.