• 한국정밀공학회지
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• 제26권6호
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• pp.90-96
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• 2009

Ultrasonic method using SH(shear horizontal) wave has been developed to determine the surface damage in fatigued material. Fatigue damages based on propagation energy were analyzed by multi-regression analysis in interrupted fatigue test specimen including CrMoV and 12Cr alloy steel. From the test results, as the fatigue damage increased the propagation time of the launched waves increased and amplitude of wavelet decreased. Also, analysis for the waveform modulation showed a reliable estimation, with confidence limit of 97% for 12Cr steel and 95% for CrMoV steel, respectively. Therefore, It is thought that SH ultrasonic wave technique can be applied to determine fatigue damage of in-service component nondestructively.

• 대한안전경영과학회지
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• 제16권4호
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• pp.371-378
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• 2014

Manual materials handling tasks are the main risk factors for the work-related musculoskeletal disorders. Many assistant tools for manual materials handling are being used in various kind of industries. One of them is a 4-wheeled cart which is widely used in manufacturing factories, hospitals, etc. The major force required to control the 4-wheeled cart is pushing and pulling. There are two types of handles being used for the 4-wheeled cart : vertical type (two vertical handles), and horizontal type (one horizontal handle). This study tried to investigate the pushing forces and subjective discomforts (hand/writst, shoulder, low back, and overall) of the two handle types with different handle height and distance conditions. Twelve healthy male students (mean age = 23.4 years) participated in the experiment. The independent variables were handle angle (horizontal, vertical), handle height (low, medium, high), and handle distance (narrow, medium, wide). The full factorial design was used for the experiment and the maximum pushing forces were measured in 18 different conditions ($2{\times}3{\times}3$). Analysis of variance (ANOVA) procedure was conducted to test the effects of the independent variables on the pushing force and discomfort levels. Handle height and angle were found to be the critical design factors that affect the maximal pushing forces and subjective discomfort. In the middle height, subjects exerted higher pushing forces, and experience lower discomfort levels compared to the high, and low height. There was no statistical influence of the handle distance to the pushing forces and subjective discomfort levels. It was found out that the effects of the handle angle (horizontal and vertical) on both pushing force and subjective discomfort were statistically significant (p < 0.05). The vertical handle revealed higher pushing force and lower discomfort level than the horizontal handle. The reason for that was thought to be the different postures of the hand when grasping the handles. The horizontal handle induced pronaton of the hand and made hand posture more deviated from the neutral position.

• Applied Microscopy
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• 제42권3호
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• pp.142-146
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• 2012

Doublecortin (DCX) is a microtuble-associated protein that is required for the migration of immature neuroblasts within the chick and mammalian brain. Although it is generally thought that DCX is expressed only in the neuroblasts, some mature neurons maintain DCX expression; for example, horizontal cells in adult rat retina. In this study, we demonstrate that retinal neural progenitors in the early embryonic stage of the chick also expressed DCX, as do developing ganglion cells and horizontal cells in later stages of development. These findings raise the possibility of a role for DCX in retinal neural progenitors, before they become specialized into neuroblasts in the chick.

• Journal of Biosystems Engineering
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• 제2권2호
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• pp.37-45
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• 1977

Solar energy is a potential source of power that offers much promise being used for low-temperature applications like drying farm crops, space heating, and water heating for domestic uses. Already much of it are being used for those purpose in foreign countries. However, very little research has been done to determine the possibility of using the solar energy in Korea. This study was conducted to develop the general prediction equation of the total radiation on a horizontal surface in Daejeon area based on 5 years 91972, Jun.1-1976. Dec.31) meteorological data (bright sunshine hours, average total horizontal radiation), and to obtain experimentally the thermal efficiency of solar air and water collectors, which will be used as a basic data of designing flat-plate solar collector system.In addition to the thermal efficiency of the collectorsthe relationship among those factors affecting it such as weather condition, orientation factor, and tilted angle of collector was analyzed. The results of this study were as follows. 1. The general predicted equation of the total radiation on a horizontal surface in Daejeon area based on bright sunshine hours was developed as $H_{av} =(1.546\frac{n}{N}-0.582)H_o$. Predicting the total radiation on a horizontal surface by the above equation was thought to be possible because to values of 0.882 was smaller than any t values at above 0.05 level on the basis of two tailed test of the difference between the calculated and the recorded values. 2.It was observed that optimum tilt angle of the collector in the summer and the autumn drying season was 13 degrees and 51 degrees respectively, these values could be obtained by adding or substracting approximately 25 degrees from the latitude of this area $(36.3^{\circ}N)$ .The relationship between orientation factor and declination of sun at suitable tilt angle of 33 degrees $(s=0.9\O)$ was shown at Fig.4. 3.The thermal efficiency of solar wdter collector was shown 13.4-51. 6% on Aug. 15 (the minimum radiation recorded) and 43.8 ~537% Aug.20 (the maximum radiation recorded), and 13.8~ 46.6 and 44.3~ 49.7 were shown on each corresponding day. 4.The thermal efficiency of the collectors according to the weather condition was shown a big difference of about 10% between the day of the maximum radiation recorded and the minimum, but the differen of efficiency between the air and the water collector was at most 2 ~ 3%. 5. Even if the efficiency of the solar water collector was a little higher than the solar air collector, for drying farm products, the solar air collector was thought to be more effective because the air heated by collector could be directly used for drying them.

• Journal of Biosystems Engineering
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• 제6권1호
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• pp.1-14
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• 1981

A laboratory model test was carried out with a newly designed model to figure out the vibration characteristics of the vibratory tillage tool according to the method of forced vibration, i.e., horizontally and vertically forced vibrations. The results are summarized as follows: 1. The reduction ratios of the draft force of the vibratory blade were 14.2-42.6% for the case where the vibration was forced parallel to the travelling direction of the blade, and 15-54.5% for the vertically forced vibration. And it was thought that the method of vertically forced vibration was preferable to the reduction of the draft force. 2. The ratio of the draft force of a vibratory blade to that of a static one could be represented as a function of V/At. It was found to be possible to reduce the draft force by taking a lower value of (V/Af) and this meant that the effictiveness of tillage practice using the vibratory system would be limited. 3. The torque to the main rotating shaft to vibrate the model blade increased frequency and amplitude. This tendency varied according to the physical properties of tested soil. In case of horizontally forced vibration, the torque was 8~34% less than in case of vertically forced vibration. 4. With the increase of frequency, the total power requirement increased linearly, and also the portion of oscillating power requirement in the total power tended to increase. The magnitude of the total power requirement was 1.4-13 times greater than that of a static one for the case of horizontal vibration, and 1.5-15 times greater for the case of vertical vibration. It was thought that the horizontal vibration of the blade was preferable to the vertical vibration in view of the power requirement. 5. A linearity was found between the amplitude of moment oscillogram and magnitude of oscillating acceleration. Only positive values of moment occurred when the blade was forced to vibrate vertically, but negative values occurred in rarity in the case of amplitude A3 when the blade was forced to vibrate horizontally.

• 건축역사연구
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• 제18권5호
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• pp.81-100
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• 2009

The study on Buddhism architecture in early Joseon dynasty was inactive. The period of King Sejo is important for studying the trend of Buddhism architecture in early Joseon, that was transmitted from the end of Goryeo dynasty, but it was difficult to know its exact situation due to lack of related records. The records were all written by Kim Su-ohn, which are Wongaksabi' 'Sangwonsajungchanggi' 'Bongseonsagi 'Geonginsajungchanggi'. The main hall was mainly second floor and there were necessarily annexed buildings at the right and left of the main hall. So the plane figure of $\Box\Box\Box$ was shown. It was a main stream for main hall. This layout may be referred to search for the origin of the layout in courtyard based structure(中庭形) in the late Joseon dynasty. Most of temples had 3 gates. Some part of horizontal corridor was used as 2 gates and the outer gate, far from main hall, was without corridor. The gate leading to front yard of main hall was called front gate, the next middle gate and the outer gate was Oisamun(外沙門) or Samun(沙門). Im most of the temples, people could enter into the front yard through pavilion which had the function of bell tower. The pavilions were located between front gate and first corridor. It is thought that this layout of the place for making bean curd outside the temple area will contribute to different studies on temples making bean cure in the future. The records about temples's foundation studied above are a little different between temples, but have more similarities. There common denominators represent the architecture tendency of Buddhist temples in the related period. It is thought that such a tendency was also shown on architecture of other temples during the reign of King Sejo as well as Buddhist temples.

• 대한치과보철학회지
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• 제35권2호
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• pp.373-384
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• 1997

In this study, 4 types of dowel pin were used to fabricate removable dies using the Pindex system. The comparison of interabutment distances between before and after sawing were conducted in each type of dowel pin, and the horizontal discrepancies in the interabutment distance according to the abutment location and the type of dowel pin were comparatively analyzed. Abutments LM(left molar), LP(left premolar), A(anterior), RP(right premolar), and RM (right molar) were used for measurement. The interabutment distances were measured between each abutment : LM-LP, LM-A, LM-RP, and LM-RM. The slide scanned image of each model was magnified on the computer screen and the measurements were conducted using the meeting point of the cross on the occlusal surface of each abutment. The results were as follows : 1. In the comparison of interabutment distances between before and after sawing in each type of dowel pin, there was no significant difference in World dowel pin(double), Bi-pin(double), Maxcel dowel pin(single). In the World dowel pin(single) there was no significant difference between LM-LPs, but in the other measurements (LM-As, LM-RPs, and LM-RMs) there was significant difference between before and after sawing(p<0.05). 2. In comparison of horizontal discrepancies of the measurement according to the abutment location, there was significant difference between measurement LM-LP($0.27{\pm}0.19mm$) and the others : LM-A($0.46{\pm}0.20mm$), LM-RP($0.38{\pm}0.25mm$), LM-RM($0.45{\pm}0.22mm$) (p<0.05). 3. In comparison of horizontal discrepancies of the measurement according to the type of dowel, there was no significant difference between each dowel. As a result when fabricating a removable die using the previously mentioned 4 types of dowel pins, it is thought that the horizontal discrepancy increased in proportion to the interabutment span length and does not depend on the type of dowel pin.

• 사상체질의학회지
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• 제10권2호
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• pp.29-40
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• 1998

동무의 사상의학은 단순히 임상적 차원에서만이 아니라 철학적 차원에서 자연관에 대한 중요한 인식론을 담고 있다. 그 내용으로서 사상의학의 사상체질을 마치 결정론적으로 해석하는 것에 대한 반론을 제기한다. 사상의학은 실체론에 근거한 서구 전통철학으로 볼 때 결정론적으로 보이지만 실제로는 인간의 의지를 더 중시하는 유기적 치심(治心)의 철학임을 보이고자 한다. 사상의학에서 본 인간의 창국단장(廠局短長)의 체질은 각기 태어나면서 정해진 것이지만, 그로 인해 모든 성정이 고정됨을 의미하는 것이 아니라 피심(治心)을 통하여 후천적인 변화와 자기 가변성에 초점을 두는 것이 바로 사상의학의 핵심이라고 본다. 철학적으로는 서구철학처럼 인식이 행위를 결정하는 것이 아니라 행위가 인식을 지배할 수 있다는 것을 주장하고자 했으며, 그 근거로서 사상의학에서 본 자연관을 도입하였다.

• 천문학회보
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• 제40권2호
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• pp.57.3-57.3
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• 2015

The formation of the Milky Way stellar halo is thought to be the result of merging and accretion of building blocks such as dwarf galaxies and massive globular clusters. Recently, Deason et al. (2015) suggested that the Milky Way outer halo formed mostly from big building blocks, such as dwarf spheroidal galaxies, based on the similar number ratio of blue straggler (BS) stars to blue horizontal-branch (BHB) stars. Here we demonstrate, however, that this result is seriously biased by not taking into detailed consideration on the formation mechanism of BHB stars from helium enhanced second-generation population. In particular, the high BS-to-BHB ratio observed in the outer halo fields is most likely due to a small number of BHB stars provided by GCs rather than to a large number of BS stars. This is supported by our dynamical evolution model of GCs which shows preferential removal of first generation stars in GCs. Moreover, there are sufficient number of outer halo GCs which show very high BS-to-BHB ratio. Therefore, the BS-to-BHB number ratio is not a good indicator to use in arguing that more massive dwarf galaxies are the main building blocks of the Milky Way outer halo. Several lines of evidence still suggest that GCs can contribute a signicant fraction of the outer halo stars.

• 태양에너지
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• 제10권2호
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• pp.44-58
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• 1990

본 연구에서는 파라핀을 채운 수평 원관의 관벽을 가열하여 축열할 때에 관내에서 일어나는 열전달현상을 다루었다. 용융이 진행됨에 따라 고액 밀도차에 의해서 고상이 아래로 가라앉는 침강형을 대상으로 하여 고상 윗부분의 액상에서는 자연대류를 고려한 열전달모델을 세우고, 고상의 하부와 관벽 사이의 액막에서는 중력과 부력 그리고 액막 내의 압력에 의한 힘간의 평형관계를 이용하여 액막 내에서의 열전도모델을 세워 이를 수치모사하여 이론적으로 해석하였다. 그리고 실제 실험에 의하여 시간에 따른 용융형태를 사진으로 기록하여 이를 분석함으로써 용융량을 구하였고 유동장을 가시화하여 이론적 결과와 비교하였다. 실험에서 얻은 전체 용융량을 상부액상과 하부액막에서 녹은 양으로 구분하여 용융이 진행됨에 따른 각 부분에서의 용융속도 변화를 알아보았다.