• Journal of Korea Water Resources Association
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• v.42 no.12
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• pp.1039-1052
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• 2009

Radar measurement with high temporal and spatial resolutions can be a valuable source of data, especially in the areas where rain gauge installment is not practical. However, this kind of data brings with it many errors. The objective of this paper is to propose a method to evaluate statistically the quantitative and qualitative accuracy at different radar ranges, temporal intervals and raingage densities and use a bias adjustment technique to improve the quality of radar rainfall for the purpose of hydrological application. The method is tested with the data of 2 storm events collected at Jindo (S band) and Kwanak (C band) radar stations. The obtained results show that the accuracy of radar rainfall estimation increases when time interval rises. Radar data at the shorter range seems to be more accurate than the further one, especially for C-band radar. Using the Monte Carlo simulation experiment, we find out that the sampling error of the bias between radar and gauge rainfall reduces nonlinearly with increasing raingage density. The accuracy can be improved considerably if the real-time bias adjustment is applied, making adjusted radar rainfall to be adequately good to apply for hydrological application.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.859-867
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• 2019

Severe weather conditions, such as heavy snowfall, rain, heatwave, etc., may affect travel behaviors of people and finally change traffic patterns in transportation networks. To deal with those changes and prevent any negative impacts on the transportation system, understanding those impacts of severe weather conditions on the travel patterns is one of the critical issues in the transportation fields. Hence, this study has focused on the impacts of a weather condition on travel patterns of public transportations, especially when a heavy snowfall which is one of the most critical weather conditions. First, this study has figured out the most significant weather condition affecting changes of public transport ridership using weather information, card data for public transportation, mobile phone data; and then, developed a decision-tree model to determine complex inter-relations between various factors such as socio-economic indicators, transportation-related information, etc. As a result, the trip generation of public transportations in Seoul during a heavy snowfall is mostly related to average access times to subway stations by walk and the number of available parking lots and spaces. Meanwhile, the trip attraction is more related to business and employment densities in that destination.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.303-320
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• 2017

Purpose of this study is understanding of group modeling process focusing on constraints with geological field trip applied on social-construction of scientific model. This study was carried out on 12 students of 3 groups who participate in the study 'S' gifted education center. Students were conducted to theme of 'How was formation of Mt. Gwanak?' on 2 field trip classes and 3 modeling classes. Semi-structured interviews, all discourse of field trip and modeling classes, records of personal and group activity were analyzed to constraints based on theoretical background proposed by Nersessian (2008). Results as follows. First, sources of constraints are scientific knowledge, contents observed by students during field trips and additional materials things to be explained by model during modeling class with geological field trip applied on social-construction of scientific model. Second, there are 3 types of constraints to affect making group modeling. It is that shared constraint which used commonly by all the group members. It called selected constraint that used during the initial modeling and later were reflected on for use in the group modeling. And it is that generated constraints, which were not in the initial modeling but were used later in the group modeling. This study suggests that not only the constraints can help to understand of making group model through how they used but also show that example of learning with geological field trip on social-construction of scientific model to contribute school science.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1329-1338
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• 2015

This article aims to develop model for the right policy Tools available from the cause analysis regarding the regional differences of subway modal split in Seoul metropolitan area. This allows two major factors of the most influential subway modal split to be proved and Portfolio Analysis is conducted. The results are as follows. Firstly, the two primary factors affecting subway modal split were shown as subway adjacent area and local line bus. It signifies that expansion of subway adjacent area, establishing the number of the subway stations and increase of local line bus are required in order to improve a diminishing subway modal split. Following that, pattern of the improvement to strengthen better subway connections are classified according to the two areas which are Concentration Area of Improvement in Subway Station Area (CAISSA) and Concentration Area of Improvement in Local Bus (CAILB). Our study revealed that Ganbukgu, Seodaemungu, Geumcheongu, and Gwanakgu were selected as the area of CAILB and Songpagu, and Junggu were selected as the area of CAISSA. As all things are considered, transportation policy makers should be taken into account in the two main factors driven by our study according to types in order to enhance the future subway share proportion.

• Journal of Korean Society of Forest Science
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• v.68 no.1
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• pp.37-45
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• 1985

The second year's results of surface fire effects on forest vegetation and soil properties and fire tolerance of various tree species were investigated in Mt. Gwanak, Kyunggi-do, successively after the study of the first year's effect in the same place. Soil moisture contents, organic matters, and most of soil nutrients including exchangeable bases had increased just after fire and went down to become somewhat constant. Available phosphorous at fired area decreased until it became similar to that at unfired area, while pH of subsoil was continuously increasing from just after fire till after 1 year. For Lespedeza and Weigela species, fire tolerance of tree crown was the lowest but reproductive capacity was the highest. And both of them were high for Rhododendron species. More exact classification into Increasers, Decreasers, Invaders and Neutral species was possible in the second year's study. According to comparison of similarities, it was found that the vegetational structure at fired area is slowly restoring to original state as time goes.

• Korean Journal of Community Nutrition
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• v.13 no.5
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• pp.682-692
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• 2008

The purpose of this study was to investigate the status of children's breakfast skipping and their mothers' needs for breakfast service at child care centers. A survey was conducted with mothers of children aged 3 to 5 years and attending child care centers in Gwanak-gu, Seoul. Out of 960 questionnaires distributed to the caregivers at 32 child care centers, 633 were returned (66% response rate), and 449 were analyzed (47% analysis rate) after excluding data from the respondents not meeting the selection criteria for this study: mothers of children aged 3 to 5 years. Over 2/3 (69%) of children ate breakfast every weekday (Breakfast Eaters) and almost 1/3 (31%) of children skipped breakfast one time or more often on weekdays (Breakfast Skippers). The collected data were compared between Breakfast Eaters and Breakfast Skippers. The average Good Dietary Practice Score of Breakfast Skippers was significantly lower than that of Breakfast Eaters, implying poorer dietary habits. A higher percentage of mothers of Breakfast Skippers (62%) responded that breakfast service was 'necessary' or 'very necessary' at child care centers than those of Breakfast Eaters (27%). A multiple logistic regression analysis was conducted to determine factors affecting mothers' needs for breakfast service at child care centers. The result showed that the children's ages, mothers' occupational status, household monthly income, frequencies of eating breakfast on weekdays and satisfaction level with morning snack provided at child care centers affected mothers' needs for breakfast service at child care centers. In particular, mothers who had a full-time job (OR = 2.06) than housewives, mothers whose children did not eat breakfast at al (OR = 3.54), ate $1{\sim}2$ times (OR = 5.50) or ate $3{\sim}4$ times (OR = 3.80) on weekdays than those whose children ate breakfast every weekday were more likely to have needs for breakfast service at child care centers than housewives. In conclusion, Breakfast Skippers tended to have poorer dietary habits than Breakfast Eaters and Full-time working mothers had higher needs for breakfast service at child care centers. This study results suggest that child care centers consider serving breakfast to children as the number of working mothers increases.

• Korean Journal of Environment and Ecology
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• v.24 no.5
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• pp.575-581
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• 2010

This study was accomplished for verifying the biotope field survey accuracy in the forests. Biotope data is used as the standard for the preservation and restoration of the urban ecosystem. The study area is the forests of Gwanak-gu, Seoul. For verifying accuracy, first we compared biotope field survey results between 2000 and 2005, second we compared between field survey results and satellite imagery. For comparing with satellite imagery, we delineated the evergreen-coniferous forests from imagery taken during winter season. As a result of comparison, the ratio of most actual vegetation types by delineated detail field surveys were matched around 92% between 2000 and 2005. But, between 2 field surveys, around 60% of total vegetation type was regionally matched. Evergreen-coniferous forests extracted by satellite imagery were regionally matched 69.4% of field survey result in 2000, and matched 80% of the result in 2005. If we consider the delineating errors from deciphering the picture, the results have high accuracy, especially 2005. The processes of verifying accuracy have not been proceeding in the part of delineating actual vegetation works. The verification of accuracy is important for the renewal process. Thus, the various verification methods will be studied and criteria should be developed for enhancing objectivity.

• The Korean Journal of Mycology
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• v.27 no.1 s.88
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• pp.68-72
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• 1999

Wood-rotting fungi of the Aphyllophorales were collected through field trips to mountain areas of the country from January to December of 1997. Through the observation and identification of specimens, two genera, Meruliopsis (type species=M. taxicola) and Pseudomerulius (type species=P. aureus), and four species, Phanerochaete calotricha, Phanerochaete chrysorhiza, Meruliopsis corium, and Pseudomerulius aureus were confirmed as new wood-rotting fungi to Korea and are registered here with descriptions.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.2
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• pp.357-377
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• 2014

The purpose of this study is to identify whether math class with clip-type contents has a significant impacts on the academic achievement and attitude of students. To answer the questions, two classes of 4th graders at Sinlim Elementary School in Gwanak-gu, Seoul were selected as subjects; they were divided into experimental group and comparative group. They were confirmed as a homogeneous group at the significance level of 0.05 during a pre-test. The findings are as follows. First, math class with clip-type contents had positive influence on the academic achievement. Second, math class with clip-type contents had positive influence on the attitude towards learning. Furthermore, proper clip-type contents for class boost their understanding and enhance their mathematical thinking with multiple views. It led to their self-confidence in learning math, developing a positive attitude towards math. The benefits of the present research can be summarized as follows. First, the math class with clip-type contents benefited both teachers and students. For teachers, it helped them boost the quality of their teaching. For students, it helped them understand the class better, improving their academic achievement. Second, the diverse, interesting contents had a positive impact on the following of the students: self-concept of math; attitude towards math; learning habits.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.146-161
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• 2004

There have been always some difficulties in target setting and conditioning of acoustic performances of the Korean traditional music hall due mainly to the lack of the information on the sound radiation characteristics of Korean musical sources. In this study, the radiation characteristics of four typical Korean traditional musical sources were investigated in precision and their usage was demonstrated: The selected musical sources were Gayageum (string), Daegeum (woodwind), Jango (drum), and Pansori Chang (vocal performance). Each sound source was located at the center of a semi-anechoic chamber and the directivity was determined by the measured sound pressure levels in every 10° angular position, for both vertical and horizontal directions. The directivity pattern of Gayageum varies from a uniform to a complex pattern having many side lobes with the increase of frequency. The main radiation of Daegeum is toward the upward direction. The directivity pattern of Jango is clearly a side-oriented one and the left direction intensity is sharper than its right side at low frequencies. For the Chang, the directivity pattern change from a uniform pattern to a frontally directed one as the frequency goes high. Measured directional and spectral characteristics of traditional Korean music sources were implemented into the computation of architectural acoustic measures for the Busan National Korean Traditional Music Hall which is under construction. Parameters such as RT, SPL, C80, IE, STI were calculated at two receiver positions by using a ray tracing technique. Significant differences in the acoustic measures at receiver positions were observed between the results in using the omni-directional source and the directional one. It is thought that the suggested source data and design method can be used as a basic reference in the future acoustic design of performance halls for the Korean traditional music.