• Journal of The Korean Association For Science Education
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• v.31 no.6
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• pp.887-900
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• 2011

Teachers use explanations to communicate important scientific ideas to students. Consequently, all biology teachers should be evaluated to determine how effective they are at constructing and communicating biological explanations. Open response questions are required to detect pre-service biology teachers' abilities to communicate robust and accurate scientific explanations. Nevertheless, multiple-choice questions are typically preferred by educators because of the common drawbacks of using open-response instruments, such as scoring time, inter-rater scoring disagreements, and delayed feedback to test takers. This study aims to measure pre-service biology teachers' competence in building scientific explanations and to investigate how accurately multiple-choice questions predict the results of open-response questions. One hundred twenty four pre-service biology teachers participated in the study and were administered 20 multiple-choice items and three open-response items designed to measure the accuracy and quality of their explanations of evolutionary change. The results demonstrated that pre-service teachers displayed higher competence when tested with multiple choice items than when tested with open response items. Moreover, scores derived from multiple-choice items poorly predicted the scores derived from open-response items. Multiple-choice items were also found to be poor measures of the consistency, purity and abundance of conceptual elements in teachers' evolutionary explanations. Additionally, many teachers held mixed-models composed of both scientific and naive ideas, which were difficult to detect using multiple-choice formats. Overall, the study indicates that multiple-choice formats are poorly suited to measuring several aspects of biology teachers' knowledge of evolution, including their ability to generate scientific explanations. This study suggests that open-response items should be used in teacher education programs to assess pre-service teachers' explanatory competency prior to being permitted to teach science to children.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.139-145
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• 2024

This paper presents the design of a voltage controlled oscillator (VCO) which is one of the key building blocks in modern wireless communication systems with small VCO gain (K_vco) variation. To compensate conventional large K_vco variation, a series varactor bank has been added to the conventional LC-tank with parallel capacitor bank array. And also, in order to achieve excellent phase noise performance while maintaining wide tuning range, a mixed coarse/fine tuning scheme(series varactor array and parallel capacitor array) is chosen. The switched varactor array bank is controlled by the same digital code for switched capacitor array without additional digital circuits. For use at a low voltage of 1.2V, the proposed current reference circuit in this paper used a current reference circuit for safety with the common gate removed more safely. Implemented in a TSMC 0.13㎛ CMOS RF technology, the proposed VCO can be tuned from 4.4GH to 5.3GHz with the K_vco (VCO gain ) variation of less than 9.6%. While consuming 3.1mA from a 1.2V supply, the VCO has -120dBc/Hz phase noise at 1MHz offset from the carrier of the 5.3 GHz.

• Journal of the Korean Regional Science Association
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• v.40 no.2
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• pp.107-130
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• 2024

Urban land surface temperature (LST) change is a major environmental factor that affects the thermal comfort, energy consumption, and health of urban residents. Most studies that explored the relationship between LST and urban built-environment form analyzed only midday LST. This study explores the diurnal variation of summertime LST in Seoul using ECOSTRESS data, which observes LST at various times of the day and analyzes whether the LST variation differs by built environment type. Launched in 2018, ECOSTRESS operates in a non-sun-synchronous orbit, observing LST with a high resolution of 70 meters. This study collected data from early morning (6:25) to evening (17:26) from 2019 to 2022 to build time-series LST. Based on greenery, water bodies, and building form data, eight types of Seoul's built environment were derived by hierarchical clustering, and the LST fluctuation characteristics of each cluster were compared. The results showed that the spatial disparity in LST increased after dawn, peaked at noon, and decreased again, highlighting areas with rapid versus stable LST changes. Low-rise and high-rise compact districts experienced fast, high temperature increases and high variability, while low-density apartments experienced moderate LST increases and low variability. These results suggest urban forms that can mitigate rapid daytime heating.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.4-23
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• 2020

The purpose of this study was to explore the diversity of Korea's iron casting technology and to examine various casting methods. The study involved a literature review, analysis of artifacts, local investigation of production tools and technology, and scientific analysis of casting and cast materials. Bellows technology, or Bulmi technology, is a form of iron casting technology that uses bellows to melt cast iron before the molten iron is poured into a clay cast. This technology, handed down only in Jeju Island, relies on use of a clay cast instead of the sand cast that is more common in mainland Korea. Casting methods for cast iron pots can be broadly divided into two: sand mold casting and porcelain casting. The former uses a sand cast made from mixing seokbire (clay mixed with soft stones), sand and clay, while the latter uses a clay cast, formed by mixing clay with rice straw and reed. The five steps in the sand mold casting method for iron pot are cast making, filling, melting iron into molten iron, pouring the molten iron into the cast mold, and refining the final product. The six steps in the porcelain clay casting method are cast making, cast firing, spreading jilmeok, melting iron into molten iron, pouring the molten iron, and refining the final product. The two casting methods differ in terms of materials, cast firing, and spreading of jilmeok. This study provided insight into Korea's unique iron casting technology by examining the scientific principles behind the materials and tools used in each stage of iron pot casting: collecting and kneading mud, producing a cast, biscuit firing, hwajeokmosal (building sand on the heated cast) and spreading jilmeok, drying and biyaljil (spreading jilmeok evenly on the cast), hapjang (combining two half-sized casts to make one complete cast), producing a smelting furnace, roasting twice, smelting, pouring molten iron into a cast, and refining the final product. Scientific analysis of the final product and materials involved in porcelain clay casting showed that the main components were mud and sand (SiO₂, Al₂O₃, and Fe₂O₃). The release agent was found to be graphite, containing SiO₂, Al₂O₃, Fe₂O₃, and K₂O. The completed cast iron pot had the structure of white cast iron, comprised of cementite (Fe₃C) and pearlite (a layered structure of ferrite and cementite).

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.40-52
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• 2023

The basic purpose of building material called tiles is waterproofing and damp proofing, and they were restricted to use on important buildings to symbolize authority. This is especially true during the Three Kingdoms period, although unearthed examples are rare. Most of these tiles are found in ruins in the Silla and Baekje regions. Tiles were excavated from the Buwon-dong ruins that show the oldest manufacturing technique in the Gaya region to date, and tiles from the early Three Kingdoms period were recently excavated from the Gimhae Bonghwang-dong ruins, which is presumed to be the site of the royal palace of Geumgwan Gaya. These are important materials that show the appearance of tiles from the early days of Gimhae, the ancient capital of Geumgwan Gaya. The tiles excavated from the Bonghwang-dong ruins are reddish-yellow because a small amount of sand was mixed in the tile material and baked at a low temperature. The tiles are thin, no traces of fabric were identified, but traces of clay bands were identified. Tapping tool marks and traces of an anvil used in pottery production are clearly observed on the inside and outside, indicating that the tiles were made in the same way as earthenware manufacturing methods. If this is connected to the genealogy of the potters who made Gaya earthenware, it is estimated that tiles and earthenware were produced together as in the Songrim-ri ruins in Bulo-dong, Incheon, Songgok-dong ruins in Gyeongju, and Mulcheon-ri ruins. To date, tiles excavated from the Gimhae area have been identified only in places believed to be the Geumgwan Gaya City Wall (Royal Palace) in the Gimhae Basin. Considering what has been recorded so far and the geographical scenery, the Bonghwang-dong remains are the only city wall candidate site, and this is clearly revealed through the existence of the excavated tiles, which proves this. Considering that a small number of tiles were excavated during this time, it is estimated that the role of tiles as a luxury product with a symbolic meaning was greater than that of roofing materials, and there were strict restrictions and controls on its use.

• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.7-7
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• 2023

Currently, the main technologies of various fourth industries are big data, the Internet of Things, artificial intelligence, blockchain, mixed reality (MR), and drones. In particular, "digital twin," which has recently become a global technological trend, is a concept of a virtual model that is expressed equally in physical objects and computers. By creating and simulating a Digital twin of software-virtualized assets instead of real physical assets, accurate information about the characteristics of real farming (current state, agricultural productivity, agricultural work scenarios, etc.) can be obtained. This study aims to streamline agricultural work through automatic water management, remote growth forecasting, drone control, and pest forecasting through the operation of an integrated control system by constructing digital twin data on the main production area of the nojinot industry and designing and building a smart farm complex. In addition, it aims to distribute digital environmental control agriculture in Korea that can reduce labor and improve crop productivity by minimizing environmental load through the use of appropriate amounts of fertilizers and pesticides through big data analysis. These open-field agricultural technologies can reduce labor through digital farming and cultivation management, optimize water use and prevent soil pollution in preparation for climate change, and quantitative growth management of open-field crops by securing digital data for the national cultivation environment. It is also a way to directly implement carbon-neutral RED++ activities by improving agricultural productivity. The analysis and prediction of growth status through the acquisition of the acquired high-precision and high-definition image-based crop growth data are very effective in digital farming work management. The Southern Crop Department of the National Institute of Food Science conducted research and development on various types of open-field agricultural smart farms such as underground point and underground drainage. In particular, from this year, commercialization is underway in earnest through the establishment of smart farm facilities and technology distribution for agricultural technology complexes across the country. In this study, we would like to describe the case of establishing the agricultural field that combines digital twin technology and open-field agricultural smart farm technology and future utilization plans.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.5
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• pp.87-96
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• 2017

This study focuses on the Andong Hahoe Village and seeks to identify the shape of the walls since the 1970s. The change of walls can be divided into four periods based on characteristics of materials, shape and distribution. The following is a summary of the results: First, In the 1970s, when Andong Hahoe Village was not designated as a cultural heritage, roof tiles hung on the earthen walls in the middle of the village were major forms. On the outside of the village, rice straw and pine needles were put on the earthen walls or bush clover walls were put in place around if walls were not built. Second, after being designated as a cultural heritage in the 1980s, readjustments for cultural heritages were carried out at the primary stage. However, the distribution of cultural heritages and major changes were not determined at this time since readjustments were mainly focused on the renovation of derelict houses or maintenance of infrastructures. Third, in the past the use of stone bricks for the Hahoe Village site had been difficult, but in the 1990s, replacements with soil-stone walls were identified and the usage of roof tiles increased. The portion of earthen walls, which used to be the major form in the prior era, decreased and this seems to have continued until the 2000s. Fourth, via a field survey, it was found that most of Hahoe village walls consisted of soil cement bricks mixed with cement, steel, lime, gravel. etc. Also, the scope of straw-stricken walls and bush clover walls were reduced to a section of area outside of the village. Fifth, from the 1970s to the present, there were changes to the walls in Hahoe Village including an increase in usages of new materials and an expansion of houses with tiled roofs on top in accordance with the replacement of walls of existing houses. Relevant reasons for this have been identified, such as the fading value of Fungsui(風水) and lack of original records, insufficient awareness and expertise in non-building areas, and the relationship between residents on repairing the wall.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.46-57
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• 2014

This study contemplated the gardening culture from the pictures, which the scholars of late Joseon Dynasty, the aspects of garden landscapes and garden use behaviors are drawn as follows. 1. The yard by the detached house for men and guest in front of the premises(Sarang Madang) and backyard were the major places for Ahoi(social gatherings of the scholars). The mansions had interests in the management of the outer garden beyond the house wall with building structures like the pavilions on the high walls and side gates. This management and the selection of location anticipating in advance of the management are noteworthy. 2. Only house gardens had plant pots with flowers and the small flower bed(Hwa-O) at Sarang Madang occasionally had plant pots without flowers and oddly shaped stone pots and equipped pine branch eaves and traditional awnings made of plant material like a trellis. 3. The oddly shaped stones were significant landscape elements in the gardens of houses and villas. Some of them were depicted as the Taihu stone and this draws attention to the question of whether the Taihu stone was actually used in the garden of late Joseon Dynasty. 4. The gardens in villas accommodated the borrowed scenery with various materials like wooden fences, bamboo or reed fences, mud walls. They also had the artificial gardens with some odd shaped stones, old pines, bamboos, Japanese apricots, willows, paulownia trees, lotuses and plantains in the secured Madangs. 5. Gyeong Hwa Sa Jog(The scholars of the ruling class adapted to the 18th century's new historical aspect) of late Joseon Dynasty built the villas at the beautiful scenery closed to the their houses. 6. The Gardens around pavilions were located high closed to the mountain streams with nature like beautiful forests, oddly formed rocks, precipitous cliffs and viewing stones. The back side of the pavilion was enclosed by bamboo forests and the front had pines, ginkgoes and willows as shade trees. 7. The beautiful scenery which was preferred as the place for Ahoi was basically with fantastic peaks and precipitous cliffs which forms the distant view harmonized with a waterfall. Broad and flat rocks at the summit of a mountain which commands a bird's-eye view or on a mountain streamside with pine forest, willows and plum trees were chosen as the optimal places for Ahoi. 8. Pine trees were presumed to be more preferable than other species in the garden, especially an single planted old pine tree accented symbolism. 9. Portable tea braziers for boiling tea were adopted in all four types of the gardens. 10. The gardens mixed with auspicious landscape elements were the places of the arts for an unworldliness Ahoi through GeumGiSeoHwa(enjoying strings, go, writing and painting) and boiling tea.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.1
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• pp.39-48
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• 2010

Recreation forests are in the spotlight as the place for personality development, mind and body comfort, companionship, and environment education in forests and valleys. Visitors to recreation forests have been on the increase along with booming in recreation forest building since 1988. Recreation forests are being categorized according to some features such as regional and environmental condition. Recreation forests, however, have not met the expectations of some visitors who want to take a rest with calmness due to the influence of the 5-day-work-week system, increasing interest in rest, leisure, and well-being, and users converge during weekends, summer, and the tourist season. In order to improve visitors' satisfaction efficiently, this study surveyed the level of satisfaction in each cluster based on the precedent study which had classified 85 national or public recreation forests in Korea into clusters. Questionnaires were distributed properly to each cluster and, of the 1,132 questionnaires collected, 1,015 were valid and used for analysis. Reliability of questionnaires and statistical validity of the model were verified. As a result, there are meaningful differences in the ranking of independent variables which affect the level of satisfaction according to clusters. Variables in rest and fatigue recovery have the strongest influence on the level of satisfaction in the clusters of potential factor, internal activation factor, and mixed potential capacity factor. In the use performance and visiting condition factor cluster, appropriateness of visit cost is most influential and, in the education cluster, connectivity with tourist attractions around it is most affective. These results can provide priority in services and maintenance of recreation forests for improving the level of satisfaction and differentiate the distribution of resources according to clusters.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.32-45
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• 2014

The study attempts to interpret original location and landscape composition of Yowol-pavilion Garden under the premise that tablet and poetry are important criteria for inference of unique location and landscape composition of a pavilion garden. The study raises the meaning, status, and value of Yowol Pavilion Garden as a cultural asset. The results of the study are as follows. First, Yowol-pavilion Garden was a place where famous Confucius scholars in Joseon Dynasty in 16th Century, including Kim, Kyung-Woo, the owner of the garden, used to share the taste for the arts and poetries with their colleagues. Along with a main characteristic of Yowol Pavilion Garden as a hideout for the Confucius scholars who stayed away from a political turmoil, the new place characteristic of the garden, a bridgehead for the formation of regional identity, was discovered in the record of "Joseon-Hwanyeo-Seungram Honam-Eupji JangSeong-Eupji", As described in "The first creative poetry of Yowol-pavilion", the intention for the creation of Yowol-pavilion Garden and the motive for its landscape composition is interpreted as a space of rivalry where the world, reality and ideals are mixed up. Second, related to outstanding scenic factors and natural phenomena when taking a view from the pavilion, the name of the house 'Yowol', which means 'Greeting the moon rising on the Mt. Wolbong' is the provision of nature and taste for the arts, and is directly connected to the image of leaving the worldly. In other words, the name was identified to be the one that reflected the intention for landscape composition to follow the provision of nature separating from joy and sorrow of the mundane world. Third, as for the location, it was confirmed through "YeongGwang-Soksu-Yeoji-Seungram" that Yowol-pavilion Garden was a place where the person who made the pavilion prepared for relaxation after stepping down from a government post, and literature and various poetry show that it was also a place of outstanding scenic where Yellow-dragon River meandered facing Mt. Wolbong. Especially, according to an interview with a keeper, the visual perception frequency of the nightscape of Yowol-pavilion Garden is the highest when viewing by considering the east, the direction of Yellow-dragon River, as Suksigak[normal angle's view], towards Yowel-pavilion from the keeper's house. In addition, he said that the most beautiful landscape with high perception strength is when the moon came up from the left side of Yowol-pavilion, cuts across the Lagerstroemia india heal in front of Yowol-pavilion, and crosses the meridian between Mt. Wolbong peaks facing Yowol-pavilion. Currently, the exposure of Yowol-pavilion Garden is $SE\;141.2^{\circ}$, which is almost facing southeast. It is assumed that the exposure of Yowol-pavilion Garden was determined considering the optimized direction for appreciating the trace of the moon and the intention of securing the visibility as well as topographic conditions. Furthermore, it is presumed that the exposure of Yowol-pavilion Garden was determined so that the moon is reflected on the water of Yellow-dragon River and the moon and its reflection form a symmetry. Fourth, currently, Yowol-pavilion Garden is divided into 'inner garden sphere' composed of Yowol-pavilion, meeting place of the clan and administration building, and 'outer garden sphere' which is inclusive of entrance space, Crape Myrtle Community Garden and Pine Tree Forest in the back. Further, Yowol-pavilion Garden has been deteriorated as the edge was expanded to 'Small lake[Yong-so] and Gardens of aquatic plants sphere' and recently-created 'Yellow-dragon Pavilion and park sphere'. Fifth, at the time it was first made, Yowol-pavilion Garden was borderless gardens consisting of mountains and water taking a method of occupying a specific space of nearby nature centering around pavilion by embracing landscape viewed from the pavilion, but interpreted current complex landscapes are identified to be entirely different from landscapes of the original due to 'Different Changes', 'Fragmentation' and 'Apart piece' in many parts. Lastly, considering that Yowol-pavilion Garden belongs to the Cultural Properties Protection Zone, though not the restoration to the landscapes of the original described in tablet and literature record, at least taking a measure from the aspect of land use for minimizing adverse effect on landscape and visual damage is required.