• Economic and Environmental Geology
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• v.6 no.2
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• pp.81-114
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• 1973

The purpose of the present study is to clarify the stratigraphy and geologic structure of the Great Limestone Series by means of study on fossil conodonts and detail investigation of geologic structure. In recent years very few geologists in Korea argue without confident evidences against the age and stratigraphy of the Great Limestone Series which have been rather well established previously in most parts of the regions although it is ambiguous and has not been studied in other areas. Five type localities in the Kangweon basin where the Great Limestone Series is well cropped out were chosen for the study. Total 26 genus and 66 species of conodont were identified from 290 samples collected and treated. From the study on conodonts the age of each formations of the Great Limestone Series has been determined as follows: The Great Limestone Series of Duwibong type Duwibong limestone: Caradocian (mid-Ord.) Jikunsan shale: Landeilian (mid-Ord.) Maggol limestone: Llanvirn-Llandeilian (mid-Ord.) Dumugol: Arenigian (Ord.) Hwajeol: Upper Cambrian The Great Limestone Series of Yeongweol type Mungok (Samtaesan) : Ordovician Machari: upper Cambrian The Great Limestone Series of Jeongseon type Erstwhile Jeongseon limestone: mid-Ord. The erstwhile Jongseon Limestone formation in Jeongseon district is separated into Hwajeol, Dongjeom, Dumudong, and Maggol formations which were cropped out repeatedly by folding and faulting, but Maggol is predominant in areal distribution. Yemi Limestone Breccia bed is not a single bed but distributed in several horizons so that it bears no stratigraphic significance. The limestone bed above Yemi Limestone Breccia, which was believed by some geologists to be much younger than Ordovician, is identified to be Maggol and its age is determined to be mid-Ordovician. Sambangsan formation in Yeongweol district was believed to be Cambrian age and lower horizon than Machari formation by Kobayashi, but C. M. Son believed that it might belong to later than Ordovician and lies above the Great Limestone Series of Yeongweol type. It was identified to be upper Cambrian and lies beneath the Machari formation and above the Daeki formation, the lower most horizon of the Great Limestone Series. The age of Yeongweol type Choseon system is contemporaneous with that of Duwibong type Choseon system. The difference in lithofacies is not due to lateral facies change, but due to the difference in its depositional environment. The Yeongweol type Choseon system is believed to be deposited in the small Yeongweol basin which was separated from the main Kangweon sedimentary basin. Judging from these facts it is definitely concluded that there exists no Gotlandian formation in the regions studied. Structurally the Kangweon basin comprises five basins and two uplifted areas. These structures were originated by at least two crustal movements, that is, Songrim disturbance of Triassic and Daebo orogeny of Jurasic age.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.58.1-59
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• 2021

Exploration of asteroids' internal structure is essential for understanding their evolutional history. It also provides a fundamental information about the history of coalescence and collision of the solar system. Among several models of the internal structures, the rubble-pile model, confirmed by the near-Earth asteroid (25143) Itokawa by Hayabusa mission [1], is now widely regarded as the most common to asteroids with size ranging from 200 m to 10 km [2]. On the contrary, monolithic and core-mantle structures are also possible for small asteroids [3]. It is, however, still challenging to look through the interior of a target object using remote-sensing devices. In this presentation, we introduce our ongoing research conducted at Seoul National and propose an idea to infer the internal structure of Apophis using available instruments. Itokawa's research provides an important benchmark for Apophis exploration because both asteroids have similar size and composition [4][5]. We have conducted research on Itokawa's evolution in terms of collision and space weathering. Space weathering is the surface alteration process caused by solar wind implantation and micrometeorite bombardment [6]. Meanwhile, resurfacing via a collision acts as a counter-process of space weathering by exposing fresh materials under the matured layer and lower the overall degree of space weathering. Therefore, the balance of these two processes determine the space weathering degrees of the asteroid. We focus on the impact evidence on the boulder surface and found that space weathering progresses in only 100-10,000 years and modifies the surface optical properties (Jin & Ishiguro, KAS 2020 Fall Meeting). It is important to note that the timescale is significantly shorter than the Itokawa's age, suggesting that the asteroid can be totally processed by space weathering. Accordingly, our result triggers a further discussion about why Itokawa indicates a moderately fresh spectrum (Sq-type denotes less matured than S-type). For example, Itokawa's smooth terrains show a weaker degree of space weathering than other S-type asteroids [7]. We conjecture that the global seismic shaking caused by collisions with >1 mm-sized interplanetary dust particles induces granular convection, which hinders the progression of space weathering [8]. Note that the efficiency of seismic wave propagation is strongly dependent on the internal structure of the asteroid. Finally, we consider possible approaches to investigate Apophis's internal structure. The first idea is studying the space weathering age, as conducted for Itokawa. If Apophis indicates a younger age, the internal structure would have more voids [9]. In addition, the 2029 close encounter with Earth provides a rare natural opportunity to witness the contrast between before and after the event. If the asteroid exhibits a slight change in shape and space weathering degree, one can determine the physical structure of the internal materials (e.g., rubble-pile monolithic, thick or thin regolith layer, the cohesion of the materials). We will also consider a possible science using a seismometer.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.659-664
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• 2001

This paper was studied to effects of fatigue by low flexural load on micro structures and carbonation of mortar. Mortar specimens cured at various conditions were first subjected to bending repeated loads, and it was made clear that insufficient cure reduced fatigue resistance of them. Next, fatigue tests that the stress levels are lower than the ones of fatigue rupture were carried out, The effect of curing conditions in early age on carbonation was furthermore studied using the scale, and it was made clear that insufficient cure is also susceptible to carbonation of them. Finally, the reason for rapid carbonation of fatigued mortars insufficiently outed was discussed from the view point of changes in pore structure of them.

• The Korean Journal of Ecology
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• v.20 no.6
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• pp.439-450
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• 1997

The potential natural vegtation of the Pukhansan National Park area, mid-western Korea, was inferred from the actual vegetation. With the phytosociological classification and field surveys, the actual vegetation map of the park area was made on a scale of 1:25, 000, including fourteen communities. By the analyses of the species diversity, the age structure, the human interferences and various informations on vegetation changes, two pathways of late stage succession from Pinus densiflora forests to the climatic climax were suggested. One is from Quercus serrata forests to Q. mongolica forests throughout the mountain and the other, from Q. variabilis or Q. acutissima forests to Carpinus laxiflora forests in lower parts. Considering the vegetation changes, the potential natural vegetation of the park area mainly composed of Q. mongolica, C. laxiflora, P. densiflora and Zelkova serrata forest as the climatic and/or edaphic climax was inferred.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.35-42
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• 1990

The area where age dating of the seafloor and interpretation of geomagnetic basic structure are conducted is also important in the aspect of geophysics. Near the sea mount (water depth to the top is 3900m and 6500m to the bottom), there are Mesozoic magnetic lineations at the sea-side flank along the trench axis. A two dimensional model analysis of Talwani and Heirtzler(1964) and a three dimensional model analysis of Talwani are performed by using data obtained from the marine proton magnetometer. Distribution, direction of the lineation, amplitude and period of magnetic anomaly are correlated and analysed with speed of the plate movement and lineation of the sea mount. In the west and north-west Pacific there are lots of huge sea mounts retaining the history of oceanic crust. This indicates that geomagnetic basis subsided into the oceanic crust and has interest in the aspects of the isostasy theory of the gravity.

• Journal of Families and Better Life
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• v.8 no.1
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• pp.143-156
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• 1990

The purposes of this study are to secure the desirable parent-adolescent cohesion, to find out the real parent-adolescent cohesion and to investigate the influences of family structure variables on the parent-adolescent cohesion. The data are obtained from a sample of 364 high school students in Seoul by using questionaires. X2-test, t-test, one-way ANOVA, Scheffe-test, Kruskal-Wallis test and difference of percentages with cross tabulation are used for data analysis. The major findings are as follows : 1) The high parent-adolescent cohesion is found to be desirable. 2) The mother-adolescent cohesion is higher than that of the father-adolescent. 3) The father-son cohesion is influenced by siblings existence, while the mother-son cohesion is influenced by siblings existence and birth order. The father-daughter cohesion is influenced by birth order and difference of age between mother and daughter. However the mother-daughter cohesion is influenced by the presence of the arents and difference of age between mother and daughter. 4) The results discribed in 3) are changed considerably by controlling the open-communication variable.

• Genomics & Informatics
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• v.1 no.1
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• pp.7-19
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• 2003

The latest measure of the relative evolutionary age of protein structure families was applied (based on taxonomic diversity) using the protein structural interactome map (PSIMAP). It confirms that, in general, protein domains, which are hubs in this interaction network, are older than protein domains with fewer interaction partners. We apply a hypothesis of 'biological network evolution' to explain the positive correlation between interaction and age. It agrees to the previous suggestions that proteins have acquired an increasing number of interaction partners over time via the stepwise addition of new interactions. This hypothesis is shown to be consistent with the scale-free interaction network topologies proposed by other groups. Closely co-evolved structural interaction and the dynamics of network evolution are used to explain the highly conserved core of protein interaction pathways, which exist across all divisions of life.

• Korean Journal of Child Studies
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• v.28 no.2
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• pp.39-53
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• 2007

This study investigated the relationship between young children's comprehension and story making(narrative) by age and gender. Subjects were 109 3-, 4-, and 5-year-olds at two child care centers in K Province. Data were analyzed by two-way ANOVA and simple regression analysis. Results showed differences in comprehension between 3-, 4- and 5-year old children and differences in story making ability between 3- and 5-year-old children. Children's comprehension and story making had positive relationships. Specifically, there were significant relationships with children's comprehension and story construct concept, sentence structure level, language(vocabulary and sentence structure). In sum, the results of this study reveal that young children's comprehension ability is partially related to story making ability by age.

• Management & Information Systems Review
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• v.3
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• pp.399-417
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• 1999

The purpose of this paper id to study the factors influencing MIS user satisfaction. For this purpose. I have reviewed the results of past studies on the performance factor of MIS, and introduced a new model associated with small & Medium Business. On the basis of this model, I have hypothesized that the following variables influence user satisfaction : (gender, age), individual characteristics(user attitude, training for user), managerial characteristic(top management involvement, organizational support) and task characteristics(task structure). There were 195 participants surveyed using questionnaires from 25 different small & medium Business in Pusan. The research model and associated hypotheses were tested by following statistical techniques: reliability test, regression, t-test and ANOVA. The findings of this study are follows; 1. It was found that gender and age are not correlated user satisfaction. 2. Among individual characteristics, only user attitude influence user satisfaction significantly. 3. While organizational supports influence positively user satisfaction, top management involvement do not influence it. 4. Task structure is highly correlated with user satisfaction. In spite of many factors affecting MIS success, this study did not consider all variables affect on user satisfaction. We need integrated model including more various factors.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.25 no.1
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• pp.20-23
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• 2014

Age-related changes in larynx can have a direct impact on voice quality and general comfort level. Observations of vocal aging have spanned perceptual, acoustic, aerodynamic, physical, electromyographic (EMG) and histological levels. Evidence of differential vocal aging in relation to gender and physical condition has been reported. Perceptual, acoustic, aerodynamic, kinematic, EMG and histological data document age-related changes in laryngeal structure and function with advancing age. These changes contribute to a functional age-related impact of vocal hypofunction or compensatory hyperfunction. This review will focus on the current understanding of the clinical and cellular changes in the larynx that lead to presbyphonia.