• 한국안전학회지
• /
• 제5권3호
• /
• pp.51-55
• /
• 1990

This study describes the engineering approach adopted to investigate sprinkler head during the early stage of a fire when they are subjected to convective heating and low gas velocities. Comparions are made between the parameters derived using basic methods, ie. ramp test, for evaluating sprinkler parameters(time constant, response time index) is illustrated. Evidence is presented that the propotion of heat loss by conduction from a sprinkler element may very typically employed in the rate of rise test. This fact alone may justfy the precautionary need to perform a limited number of rate of rise tests to confirm a sprinklers capacity to function correctly in reasonably unfavourable yet realistic conditions. The work is aimed primarily at meeting the needs of sprinkler industry.

• The Korean Journal of Ecology
• /
• 제15권3호
• /
• pp.247-255
• /
• 1992

In order to estimate effects of air pollution for herbs in the plnus thunbergii forests arrounding onsan industrial complex, this study was surveyed. number of species of herb also had a difference over 10 species by distance at the source of air pollution, and species diversity and evennes were also increasing at remote sites in industrial complex as woody plants. At the vicinity of industrial complex, $SDR_4$ of calamagrostis arundinatios arundinacea., miscanthus sinensis and cymbopogon tortilis var. goeringii were very high, and those of lianas as cocculus trilobus, lonicera japonica and paederia scandens, and phytolacca americana were low, but because of being higher than other sites, it was able to inferred that lianas had a tolerance to air pollution. The composition of biological spectra of herbs showed to type of $H-D_1-R_{2-3}-1$ at near site in the source of air pollution and $H-D_1-R_{1-3}-t$ at the other sites, and the propotion of lians forms were relatively high at the vicinity of industril complex.

• 한국표면공학회지
• /
• 제20권2호
• /
• pp.60-73
• /
• 1987

For the purpose of improving the cyclic oxidation resistance of Ni-base superalloy, Inconel 600, aluminide coating methods are studied. The formation rate of aluminide coating layers is measured as a function of time and pack composition to find out the optimum coating condition. The evaluation of cyclic oxidation is established by the change in weight, the microphotography and EPMA of cross sectional area during $200^{\circ}C\;{\leftrightarrow}\;950^{\circ}C\;and\;200^{\circ}C\;{\leftrightarrow}\;1100^{\circ}C$, respectively. The thickness of coating layer and weight gains are parabolic behavior in propotion to time and Al contents. In pack of low aluminum contents, 2 wt%, however, weight gain is decreased when activator, $NH_4Cl$ is higher than 2 wt%. The cyclic oxidation resistance of the coating carried out at 1100$^{\circ}C$ are superior to those of the coating diffusion-treated after pack cementation at 800$^{\circ}C$. Aluminide oxide, which is formed in external scale, is barrier to the cyclic oxidation.

• 한국농공학회지
• /
• 제27권2호
• /
• pp.23-37
• /
• 1985

This studies were carried out to get characteristics of frequency distribution, probable flood flows according to the return periods, and the correlation between return periods and those length of records affect the Risk of failure in the annual maximum series of the main river systems in Korea. Especially, Risk analysis according to the levels were emphasized in relation to the design frequency factors for the different watersheds. Twelve watersheds along Han, Geum, Nak Dong, Yeong San and Seom Jin river basin were selected as studying basins. The results were analyzed and summarized as follows. 1. Type 1 extremal distribution was newly confirmed as a good fitted distribution at selected watersheds along Geum and Yeong San river basin. Three parameter lognormal Seom Jin river basin. Consequently, characteristics of frequency distribution for the extreme value series could be changed in connection with the watershed location even the same river system judging from the results so far obtained by author. 2. Evaluation of parameters for Type 1 extremal and three parameter lognormal distribution based on the method of moment by using an electronic computer. 3. Formulas for the probable flood flows were derived for the three parameter lognormal and Type 1 extremal distribution. 4. Equations for the risk to failure could be simplified as $\frac{n}{N+n}$ and $\frac{n}{T}$ under the condition of non-parametric method and the longer return period than the life of project, respectively. 5. Formulas for the return periods in relation to frequency factors were derived by the least square method for the three parameter lognormal and Type 1 extremal distribution. 6. The more the length of records, the lesser the risk of failure, and it was appeared that the risk of failure was increasing in propotion to the length of return periods even same length of records. 7. Empirical formulas for design frequency factors were derived from under the condition of the return periods identify with the life of Hydraulic structure in relation to the risk level. 8. Design frequency factor was appeared to be increased in propotion to the return periods while it is in inverse proportion to the levels of the risk of failure. 9. Derivation of design flood including the risk of failure could be accomplished by using of emprical formulas for the design frequency factor for each watershed.

• 복식
• /
• 제66권5호
• /
• pp.113-121
• /
• 2016

The purpose of this study is to analyze the types and characteristics of wedding ceremony robes in the Jeju area from the 1950's to the 1980's. The analysis used 413 wedding pictures. The results of the study are as follows: 1. The following are the propotion of robe types used wedding ceremonies. 1.0% of Danryeong & Jangot, 6.5% of Danryeong & Wonsam, 1.5% of Danryeong & Chima+Jegori, 2.7% of Durumaki & Chima+Jegori, 24.7% of suit & Chima+Jegori and 63.7% of suit & wedding dress from the 1950's to the 1980's. 2. The Korean-style robes gradually decreased from the 1950's, and disappeared in the 1970's. The Chima+Jegori was introduced in the 1950's, reached its peak in the 1960's and its popularity continued to the 1970's. In the 1980's, after the Korean-style robes disappeared, the western ceremony robes were used in all the ceremonies. 3. After the Western-style robes, in which a bride wears a wedding dress, was introduced in the 1960's, its usage rapidly increased in the 1970's and is still popular today.

• 대한방사선기술학회지:방사선기술과학
• /
• 제14권1호
• /
• pp.23-28
• /
• 1991

Automatic exposure control systems are now readily available and widly used in radiography. A device that automatically determines the amount of radiation required to produce an acceptable level of film blackness is called a phototimer, or automatic exposure control. There are limitations in the use of phototimers ; however, equipment can be used much more effectively if one recognize these limitations, and the goal of obtaining a properly exposed, reproducible radiography can be achieved. We have some results in this experimental study. The variations of film density due to kVp are in propotion to below 80 kVp range. But indicate constant level above 80 kVp to 120 kVp. The characteristic density variation by phantom thickness shows the higher the thiner in exit type. AEC system have a density control that is designed to make adjustments increase or decreas the density 10% per step or 25% per step. The automatic exposure control circuits must meet the several regulations of the HEW. Some forms of technique chart is recomened for use of AEC.

• 토지주택연구
• /
• 제9권4호
• /
• pp.10-18
• /
• 2018

As the volatility increasement of the number of tourist, there was been controversy over supply-demand imbalance in hotel market. The purpose of this study is to analysis on determinants of hotel occupancy rate in Jeju Island. The quantitative method is based on cointegrating regression, using an empirical dataset with hotel from 2000 to 2017. The primary results of research is briefly summarized as follows; First, there are high relationship between total hotel occupancy rate and hotel occupancy of foreign tourist. The volatility of hotel occupancy is caused by foreigner user than local tourists though local tourist high propotion of hotel occupancy in Jeju Island. Second, hotel occupancy of local tourist has not relationship with demand and supply variables. Because some hotel users are not local tourists but local resident, and effects to other variables of hotel consumer trend, accommodation such as Guest house, Airbnb. Third, there are high relationship between foreign hotel occupancy rate and demand-supply variables. These research imply that total management of supply-demand is very important to seek stability of hotel occupancy rate in Jeju Island. Also it can provide a useful solution regarding mismatch problem between supply-demand as well as development the systematic forecasting model for hotel market participants.

• 한국인터넷방송통신학회논문지
• /
• 제17권4호
• /
• pp.123-128
• /
• 2017

본 논문은 SMMA (Sliced Multi Modulus Algorithm) 등화 알고리즘에서 등화기의 출력 전력에 비례하는 adaptive modulus와 adaptive stepsize를 적용하므로서 등화 성능을 개선할 수 있는 Hybrid-SMMA 알고리즘에 관한 것이다. 기존 SMMA 알고리즘에서는 등화기의 탭 계수 갱신을 위한 오차 신호를 발생할 때 송신측 신호의 통계 특성치인 modulus를 고정적으로 사용하지만, 제안 Hybrid-SMMA에서는 등화기 출력 신호의 전력에 비례토록 modulus와 오차 신호의 비선형성을 이용하여 stepsize를 적응적으로 변화시킨다. 제안 알고리즘의 개선된 등화 성능을 컴퓨터 시뮬레이션을 통해 확인하였으며, 시뮬레이션 결과 제안 방식이 기존 SMMA보다 모든 성능에서 우월함을 확인하였다.

• 한국환경보건학회지
• /
• 제17권1호
• /
• pp.13-19
• /
• 1991

Interest in the studies of diesel exhaust emission has been increasing by the expected increase in the use of diesel powered automobiles out of concideration of fuel economy. It was well known that diesel exhaust emission was mutagenic in the bioassay as Ames test. The authors tried to find out the cytogenetic effect of diesel exhaust emission by the operational condition of engine such as speed and load. For the investigation of those effects, 66 male mice of ICR strain were used. The benzene-ethanol extracts of diesel exhaust emission were injected intra peritoneum 25rng/kg and 50mg/kg respectively. To evaluate the cytogenetic effect, mouse bone marrow micronucleus test was carried out. The frequency of micronucleus was different among the various groups according to the operational conditions of engine. The frequency of micronucleus in idling group was the highest of all the groups the subgroup of 50mg/kg showed the rate of 1.30%, 25rng/kg subgroup 0.55%. And the group of 2000rpm with 50% load showed the lowest rate of micronucleus appearance as 0.20% and 0.15%. In general, the frequency of micronucleus was shown higher in propotion to load and was shown inversely proportional to speed.

• 대한토목학회논문집
• /
• 제10권1호
• /
• pp.125-134
• /
• 1990

본연구(本硏究)는 집중대량(集中大量)으로 부산(副産)되어 막대한 경비(經費)를 들여 폐기(廢棄)처리 되고 있는 석탄회(石炭灰)를 도로로반재(道路路盤材)로서 활용하고자 시멘트를 첨가(添加)하여 반복하중(反復荷重)을 가하였을 때의 변형특성(變形特性)에 대해서 영동화력발전소(嶺東火力發電所)와 영월화력발전소(寧越火力發電所)에서 발생(發生)되는 석탄회(石炭灰)를 대상으로 검토(檢討)한 것이다. 석탄회(石炭灰)에 시멘트 첨가율(添加率)이 증가(增加)할 수록 일축압축강도(一軸壓縮强度)는 직선적(直線的)으로 증가(增加)하였고, 시험 조건인 재하회수(載荷回數)에서는 탄성계수(彈性係數)가 감소하였으며, 압축강도(壓縮强度)는 약 21% 정도의 증가를 보였다.