• 한국지진공학회논문집
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• 제18권2호
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• pp.89-94
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• 2014

Spatial variations of a seismic wave are mainly wave passage and wave scattering. Wave passage effect is produced by changed characteristics of exciting seismic input motions applied to the bedrock. Modified input motions travel horizontally with time differences determined by apparent shear wave velocity of the bedrock. In this study, wave passage effect on the seismic response of a structure-soil system is investigated by modifying the finite element software of P3DASS (Pseudo 3-Dimensional Dynamic Analysis of a Structure-soil System) to apply inconsistent (time-delayed) seismic input motions along the soft soil-bedrock interface. Study results show that foundation size affected on the seismic response of a structure excited with inconsistent input motions in the lower period range below 0.5 seconds, and seismic responses of a structure were decreased considerably in the lower period range around 0.05 seconds due to the wave passage. Also, shear wave velocity of the bedrock affected on the seismic response of a structure in the lower period range below 0.3 seconds, with significant reduction of the seismic response for smaller shear wave velocity of the bedrock reaching approximately 20% for an apparent shear wave velocity of 1000m/s at a period of 0.05 seconds. Finally, it is concluded that wave passage effect reduces the seismic response of a structure in the lower period range when the bedrock under a soft soil is soft or the bedrock is located very deeply, and wave passage is beneficial for the seismic design of a short period structure like a nuclear container building or a stiff low-rise building.

• 한국지진공학회논문집
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• 제17권1호
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• pp.1-10
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• 2013

In order to predict inelastic displacement response without nonlinear dynamic analysis, the equal displacement rule can be used for the structures with longer natural periods than the characteristic period, $T_g$, of earthquake record. In the period range longer than $T_g$, peak displacement responses of elastic systems are equal or larger than those of inelastic systems. In the period range shorter than $T_g$, opposite trend occurs. In the equal displacement rule, it is assumed that peak displacement of inelastic system with longer natural period than $T_g$ equals to that of elastic system with same natural period. The equal displacement rule is very useful for seismic design purpose of structures with longer natural period than $T_g$. In the period range shorter than $T_g$, the peak displacement of inelastic system can be simply evaluated from the peak displacement of elastic system by using the inelastic displacement ratio, which is defined as the ratio of the peak inelastic displacement to the peak elastic displacement. Smooth hysteretic behavior is more similar to actual response of real structural system than a piece-wise linear hysteretic behavior such as bilinear or stiffness degrading behaviors. In this paper, the inelastic displacement ratios of the smooth hysteretic behavior system are evaluated for far-fault and near-fault earthquakes. The simple formula of inelastic displacement ratio considering the effect of $T_g$ is proposed.

• 한국수자원학회논문집
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• 제56권1호
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• pp.1-9
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• 2023

현재까지는 연중 하천유량의 관리기간은 홍수기와 비홍수기로 구분하고, 관리해야 할 유량의 범위는 갈수량에서 홍수량까지로 폭넓게 규정하고 있다. 본 연구에서는 4대강 8개 지점의 장기간 일평균유량 자료를 이용하여1년을 유량의 분산과 평균이 동질한 기간들로 구분하고, 기간별 유량의 평균과 표준편차를 이용하여 유량의 관리범위를 설정하는 방안을 제시한다. 연구결과, 연중 관리기간은 지점에 따라 차이는 있으나 홍수기 이전, 홍수기, 홍수기 이후로 구분할 수 있었으며, 기간을 세분화하면 최소유량에 대한 최대유량의 비도 낮아지는 것을 알 수 있었다. 또한, 연중 일평균유량이 갈수량 이상 홍수량 이하가 되도록 기간별 일평균유량의 관리범위를 기간별 일평균유량의 평균 ±표준편차로 설정하는 방안도 제시하였다.

• 대한조선학회논문집
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• 제52권2호
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• pp.135-142
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• 2015

The Anti-Rolling Tank(ART) has an advantage over the other roll stabilizing devices, when ship is staying and working at one site of sea. An important design point of ART is the tank tuning, that is, matching the tank natural period to the ship's roll natural period. Since the load condition and consequently the roll natural period of ship is to be changed widely, the natural period of ART also has to be changed widely. In case of the existing U-tube type ART with a single layer duct, the tank natural period can be changed in a relatively narrow range. This paper suggests a new U-tube type ART system using a double layer duct to enable wide change of ART natural period. Through the roll experiments performed in regular beam waves for a box-type model ship, it is shown that the double layer duct ART has about two times wider period range and a better reducing effect of roll magnitude than the single layer duct ART.

• 대한물리치료과학회지
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• 제6권1호
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• pp.923-929
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• 1999

The purpose of this study was to identify that the effect of the Lumbar extensor strengthening exercise on the trunk range of motion(Lumbar extensor strengthening exercise group = 15, Control group = 15). To find out the improvement of trunk range of motion, each group was examined with Modified Modified Sch ber(MMS) measurement before and after the treatments. The result are as followed. 1. After the training period, the trunk range of motion were increased in both groups. 2. After the training period, both groups revealed no sinigificant difference on the trunk range of motion.

• 대기
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• 제16권1호
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• pp.49-53
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• 2006

The present study has examined interdecadal variations of the diurnal temperature range (DTR, daily maximum temperature minus daily minimum temperature) during the New Year season in Seoul for the period 1954-2005. Here, the average DTR for the New Year holidays (three consecutive days; one day before the New Year, the New Year day, and one day after the New Year) minus the average DTR for 14 days, 7 days before and 7 days after the New Year holidays, is defined for representing the New Year effect. The DTR index does not show notable trend until the late 1970s but shows obvious positive values afterward. For example, the difference of the average DTR between two periods (1980-2005 minus 1954-1979) is $0.65^{\circ}C$, which is meaningful at the 95% confidence level. This result demonstrates that intense human activity even for the limited period may provide climate impact in local regions. Its plausible causes are discussed.

• 대한수의학회지
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• 제32권2호
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• pp.267-273
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• 1992

The purpose of present study was to investigate the progesterone concentrations throughout gestation and peripartum period, and the return to the first estrus postpartum for improvement of reproductive efficiency in Korean native goats. The average length of gestation was 148 days(range : 144~154 days) and the average number of live births was 2 kids(range : 1~5 kids) in 12 Korean native goats. Progesterone concentrations were measured in blood samples taken from 12 goats every 5 days during gestation period. Plasma progesterone concentrations were 0.10 ng/ml at Day 0 of pregnancy and increased gradually until Day 20(6.58 ng/ml). Then they decreased slightly from Day 30 to 40(range : 4.32~4.82 ng/ml), increased again after Day 40 and remained thereafter until Day 140(range : 4.32~10.36 ng/ml). The progesterone levels declined sharply to basal levels at parturitum. Plasma progesterone concentrations during the pestpartum were 6.98 ng/ml at 10 days, 4.86 ng/ml at 6 days 3.18 ng/ml at 2 days before parturition, and 0.10 ng/ml at parturition, respectively. The basal levels were maintained until the first estrus postpartum. The mean intervals from parturition to the first estrus postpartum on the basis of progesterone determination and estrus detection were $100{\pm}64(mean{\pm}S.D.)$ days in 7 Korean native goats.

• The Journal of Korean Physical Therapy
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• 제35권1호
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• pp.8-12
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• 2023

Purpose: Recently, many studies on robotic rehabilitation have been conducted, but such studies on patients with ankle sprains are lacking. This study aimed to investigate the effects of robot-assisted rehabilitation on the range of motion of the ankle and balance in patients with ankle sprain. METHODS: This study used the A-B-A' design and was conducted for a total of fifteen days. The subjects performed general physical therapy for five days each, during the baseline A and A' periods. In period B, robot rehabilitation was performed for five days, along with general physical therapy. The subjects were evaluated based on weight-bearing lunge test (WBLT), single leg stance (SLS), and functional reach test (FRT). RESULTS: The WBLT, STS, and FRT showed significant improvement in periods B and A' compared to period A, but there was no significant improvement in period A' compared to period B. Conclusion: This study confirmed that robot-assisted rehabilitation was an effective intervention for improving the function of patients with ankle sprain. In the future, a study with a control group comparison should be performed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.125-132
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• 2006

To estimate the local site effects at two town fortress areas where stone parapets were collapsed during historical earthquakes, site characteristics were evaluated using borehole drillings and seismic tests and equivalent-linear site response analyses were conducted based on the shear wave velocity (Vs) profiles determined from site investigations. The study sites are categorized as site classes C and B according to the mean Vs to 30 m ranging from 500 to 850 m/s, and their site periods are distributed in short period range of 0.06 to 0.16 sec. For site class C in the study areas, the short-period (0.1-0.5 sec) and mid-period (0.4-2.0 sec) site coefficients, $F_{\alpha}$ and $F_\nu$ specified in the Korean seismic design guide, underestimate the ground motion in short-period band and overestimate the ground motion in mid-period band, respectively, due to the characteristics showing high amplification in short period range, which can result in the collapse of stone parapets having the short natural period.

• 경영과정보연구
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• 제30권2호
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• pp.237-255
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• 2011

변동성을 측정하는 데에는 주로 종가기반(close-to-close)의 수익률 자료를 이용하여 이루어지고 있지만, 일중 변동폭을 나타내는 가격범위에 관한 정보인 고가와 저가를 포함한 범위변동성에 대한 연구가 최근 활발해지고 있다. 본 연구는 범위 변동성에 대한 개념이 생긴 이후 최근 확장되고 있는 다양한 연구주제와 더불어 범위변동성을 실무적으로 활용하기 위한 것으로 범위변동성 예측에 있어 적절한 예측기간을 제시하는 것을 목적으로 하고 있다. 범위변동성은 Parkinson(1980; PK), Garman and Klass(1980; GK) Rogers and Satchell(1991; RS), Yang and Zhang(2008; YZ)이 제시한 추정치를 이용하였으며, AR(1), MA(1)모형을 이용하여 예측된 변동성과 실현변동성간의 예측오차를 비교하는데 이때 예측기간을 시변하여 산출함으로써 예측력을 비교분석하였다. 2000.5.22~2009.9.18(총 2,307일간)의 KOSPI200지수를 대상으로 분석한 결과는 다음과 같다. 첫째, PK, GK, RS, YZ 변동성 중 KOSPI200의 변동성을 가장 잘 예측하는 변동성은 PK변동성 또는 RS변동성으로 보인다. 두 변동성의 예측력 우위는 분석기간에 따라 미세한 차이를 보이는데 금융위기를 포함하는 경우 PK변동성이 우수하며, 포함하지 않는 경우는 RS변동성이 우수한 것으로 나타났다. 둘째, 금융위기를 포함하지 않는 경우 대부분의 경우 예측오차가 크게 줄어드는 것으로 나타나 금융위기처럼 변동성이 크게 나타나는 경우에는 범위변동성을 이용한 변동성예측력이 상당히 떨어질 수 있음을 확인하였다. 셋째, 범위변동성을 이용하여 변동성을 예측하는 경우 AR(1), MA(1)모형의 모수추정기간을 길게 하는 경우 예측오차의 평균은 감소하는 경향이 확인되었다. 특징적인 점은 60일 또는 90일로 기간을 늘일 경우에 예측오차가 급격하게 감소하는 경향을 보이는 것인데, 각각의 변동성과 예측모형에 따라 다소의 차이가 나타난다. 그리고, 예측오차의 편차는 90일 이후 큰 변화를 보이지 않고 있는 것으로 보인다. 따라서, 범위변동성을 이용하여 범위변동성을 예측할 경우 90거래일 이상의 가격 정보를 이용하여 예측을 하는 것이 예측오차를 줄여 예측력을 높일 수 있을 것으로 판단된다.