• Korea Trade Review
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• v.48 no.3
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• pp.107-130
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• 2023

This study examines the economic effects of a developed country's minimum quality standards (MQS) and mutual recognition agreements (MRAs) between countries. Based on the results of such analysis, it also considers the optimal MRA strategy for South Korea. For this purpose, the paper constructs a simple three-country model in which the representative firms in each country supply differentiated goods to the developed country market. The analysis results are as follows: First, the rise in the MQS of a developed country intensifies the competition level, reduces the profits of all firms, and raises the developed country's consumer surplus. In addition, if one of the firms exits the market due to the MQS, competition is relaxed, and the profits of the remaining firms increase. Second, countries subject to MQS can improve their social welfare through the MRAs; thus, it is essential to utilize them strategically. In the case of South Korea, the optimal situation is to have an MRA with the developed country or for all three countries not to have any MRA.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.643-659
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• 1997

For the total treatment of skeletal malocclusions, 3-dimensional evaluation and diagnosis are essential. Although anteroposterior discrepancies can be evaluated through various methods, the satisfactory methods for evaluations of facial asymmetry and transverse discrepancies are yet to be found. The adequate diagnosis and treatment of transverse discrepancies may be more important in the maintenance of functional occlusion as well as for the stability of results obtained from orthognathic surgery than the anteroposterior or vertical discrepancies. Since the soft tissue effects from the transverse discrepancies may not be pronounced, especially when combined with anteroposterior or vertical discrepancies which have prominent characteristics, the differentiation of their effects may be difficult from visual inspection alone. Therefore it is essential that the normal facial proportions would be established from the posteroanterior cephalometry as a reference for the accurate diagnosis and treatment. The present study evaluates 76 subjects from Yonsei University freshmen with normal facial symmetry and occlusion. Posteroanterior cephalograms were taken from the subjects and the normal values and facial proportions are obtained. The results are as follows. 1. The transverse and vortical values from posteroanterior cephalometry and their ratio, with means and standard deviations are calculated. 2. The ratio of vertical values to transverse values is 0.837 (male 0.836, female 0.841). 3. The Proportion of maxillary and mandibular widths is 0.747 (male 0.745, female 0.752), with statistically significant correlation. 4. Various degree of significant correlations are observed in the following craniofacial widths; (Cranial width, Bizygomaticofrontal suture width, Facial width, Maxillary width, Upper & Lower Intermolar width, Mandibular width). 5. Although the facial height as well as other line measurements increase as the facial widths increase, angle measurement ($Bj\ddot{o}rk$ Sum, Mandibular Plane Angle, Gonial Angle), decreases and posterior to anterior facial height ratio increases, therefore indicating the tendency for a brachycephalic facial type. These results may be used as references for the treatment planning in orthognathic and orthodontic treatments for the dentofacial deformity patients.

• Journal of the Korean Geographical Society
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• v.30 no.4
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• pp.352-363
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• 1995

This study explores horizontal equity problems in the Seoul Subway System by using costs per passenger kilometer as a comparison index. In general, subway users in the central area, except Line 1, are subsidizing users in fringe areas. Spatial differentiation of user cross subsidies in the area is due mainly to interactions between factors such as vehicle kilometers traveled, number of passengers, and length of segments. In order to decrease levels of user cross subsidies among the users and so relieve honzontal equity problems associated with subway use, it is necessary to develop a user fare system in which portions of marginal costs of subway use can be distributed properly among users. However, two-stage fare structure of the subway system in the study area is based only on trip distance, and so marginal costs associated with subway use are not properly reflected in user fees. Therefore, horizontal equity of the system in the study area is affected because of inappropriate user fees.

• Journal of the Korean earth science society
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• v.37 no.6
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• pp.332-345
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• 2016

The columnar joints in Goheung are developed in three places of Yuju-san area, Palyeong-san and Yongbawi area. Vertical and fan-shaped columnar joints which have maximum width 100 m and maximum heigh 50 m are developed in the Yuju-san area Columnar joints are developed next to the road near the the Yuju-san and along the coast of Jijuk-do. Thick columnar joints of maximum width 1m are developed in the Paryeong-san area. Horizontal columnar joints of maximum width 50 cm at length of polygon side are developed on dyke in the Yongbawi area. The columnar joints show high rate of rectangles and pentagons in the number of polygons. The length of polygon side of columnar joints in study area ranges from 10 to 100 cm, and 20 cm among the range appears in high frequency. Columnar joints are developed vertically to the ground from the cooling surface in Yuju-san and Palyeong-san area. Columnar joints in Yongbawi area are developed vertically to the contact of country rocks. As a result, the columnar joints began cooling from the country rock contact. And columnar joints are developed vertically to contact surface. The rocks in columnar joints is rhyolitic welded tuff in Yuju-san and Palyeong-san area, dacite in Yongbawi area. In the acid volcanic rocks flow structure well developed. The white phenocryst mineral about 2 mm size by eye, is usually feldspar, and includes some quartz. The rate of $SiO_2$ is 70wt.% or more. It is the last stage of differentiation to calc-alkaline series. The columnar joints of the Yuju-san area are expected to be distributed along a band that extends to about 1km east of the stone pit.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.55-65
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• 2006

This paper presents the closing analysis of a symmetric steel cable-stayed bridge erected by a free cantilever method. Two independent structural systems are formed before the closing procedure of a bridge is performed, and thus the compatibility conditions for vertical displacement and rotational angle are not satisfied at the closing section without the application of proper sectional forces. Since, however, it is usually impossible to apply sectional forces at the closing section, the compatibility conditions should be satisfied by proper external forces that can be actually applicable to a bridge. Unstrained lengths of selected cables and the pull-up force of a derrick crane are adjusted to satisfy nonlinear compatibility conditions, which are solved iteratively by the Newton-Raphson method. Cable members are modeled by the elastic catenary cable elements, and towers and main girders are discretized by linear 3-D frame elements. The sensitivities of displacement with respect to the unstrained lengths of selected cables and the pull-up force of the derrick crane are evaluated by the direct differentiation of the equilibrium equation. A Monte-Carlo simulation approach is proposed to estimate expected construction errors for a given confidence level. The proposed method is applied to the second Jindo Grand Bridge to demonstrate its validity and effectiveness.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.53-68
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• 1997

Lake Shihwa, artificially constructed since 1988, shows a typical two-layered system depending on strong haline density stratification. Sill of the water gate at 6 m depth greatly restricts physical mixing with outer seawater and circulation in the lake, and contributes to the enhancement of anoxic environment in the deeper layer. With this enclosed physical environment, Lake Shihwa receives enormous amounts of organics, ammonia, and other pollutants from the neighboring municipal and industrial complexes through six major streams, thus developing biogeochemical differentiation of anoxic to suboxic environment in the high saline bottom water and highly eutrophicated brackish surface water. This study investigated vertical structures, biogeochemical behaviors and processes of various organic and inorganic compounds around oxic-anoxic interface. Nitrite and nitrate rapidly decreased below the pycnocline where about $1{\times}10^8$ tons of hypoxic bottom water exist. In this bottom layer, ammonium ranged from 75 to 360 ${\mu}M$ mainly resulting from deamination of dissolved organic nitrogen and ammonification of precipitated organic particles. Despite large amounts of surface water discharge and dilution by outer seawater inflow about $3{\times}10^8$ tons from April to August, 1996, bottom layer did not show any improvement of water quality and maintained highly reduced environment. The main reason seems to be imbalance between ineffectiveness of dilution due to shallow depth and large surface area, overloaded POC influx from the eutrophicated surface biological activity, and poor replenishment of oxygen in this artificial lake system. Therefore, as long as current salinity dependent two-layered system maintains with its physical limitations, any improvement of water quality cannot be foreseen in Lake Shihwa.

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.154-201
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• 2016

During the Incipient and Early Silla phases, which witnessed the establishment and development of the ancient Silla state, the Wolseong North Burial Ground functioned as not only the central burial ground in the Gyeongju region of the capital of Silla but also as the central burial ground of the whole Silla state. Wolseong North Burial Ground is where transformations in Silla funerary architecture first occurred. As such, an empirical study of the tombs constructed at this burial ground can be regarded as a starting point from which an understanding of the development of the tomb culture of the Silla state may be achieved. This paper therefore aims to examine the changing nature of the tomb culture of the Early Silla phase through the burial data of Wolseong North Burial Ground and the Gyeongju region. Wooden chamber tombs were constructed from the late phase of Saroguk. At Wolseong North Burial Ground, which eventually developed into the central burial ground of the Gyeongju region, wooden chamber tombs embellished with stone packing emerged during the Incipient Silla phase; wooden chamber tombs with stone mounds, on the other hand, first appeared in the Early Silla phase and eventually became established as the central tomb type. A key difference between the wooden chamber tomb embellished with stone packing and the wooden chamber tomb with stone mound is that, in the case of the latter, stones were packed not only around sides of the wooden structure that acted as the burial chamber but also on top of this structure. The addition of a high earthen mound surrounded by protective ring of stones is another distinctive feature of the latter, presenting a contrast to the low mound of the former. During the Early Silla phase, two types of wooden chamber tombs with stone mounds were constructed at Wolseong North Burial Ground: those with burial chambers located above ground and those with subterranean burial chambers. Also constructed during this phase were the wooden chamber tomb embellished with packed stones, the wooden chamber tomb embellished with packed clay, simple earth cut burials, which had been used since the Incipient Silla phase, as well as the stone-lined burials with vertical entrance which first appeared in the Early Silla phase. However, of these different types of burials, it was only the wooden chamber tomb with stone mound that was covered with a 'high mound.' Differentiation between the different tomb types can also be observed in terms of location, type of burial chamber used, construction method, and tomb size. It is therefore possible to surmise that stratification between the different tomb types, which first emerged in the Incipient Silla phase, became intensified during the Early Silla phase.