• Journal of Korean Society for Atmospheric Environment
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• 제16권E호
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• pp.47-57
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• 2000

This study focuses on the investigation of the effects of windspeed and particle size on the dust control characteristics inside a test dome built in the Port of Inchon to reduce the fugitive dust originating from the handling of animal feed stuff in the open pile area. The flow field inside the test dome and the trajectories of the particles were calculated using a commercial CFD code, FLUENT, assuming that the animal feed stuff handling activity took place inside the test dome. It was found from the simulation results that high windspeed and small particle size give rise to the increase in both the escaped fraction and the suspended fraction of the particles emitted from the animal feed stuff handing activity. Here, high escaped fraction represents the high possibility of fugitive dust problem outside the test dome, whereas high suspended fraction means the high possibility of severe dust pollution inside the test dome. Ore simulation results clearly show that the existing test dome was not designed properly to meet the proposed goal, low escaped fraction and low suspended fraction. Hence, we suggest the need of an efficient ventilation system inside the dome to control the dust.

• 항공우주기술
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• 제6권1호
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• pp.190-200
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• 2007

파이로젠 형 점화기를 KSLV-I 킥모터 시스템 요구 조건을 만족하도록 설계하였다. 비행모델 제작에 앞서 신뢰성을 확보하기 위해 구조시험, 환경시험, 연소시험을 수행하였다. 점화기 구성품들의 구조적 강도를 확인하기 위해 수압 시험을 수행하였다. 극심한 환경 조건에서 점화기가 정상적으로 작동하는 지를 확인하기 위해 충격 및 진동 시험을 고려하였다. 그리고 초기 조건의 변화에 따른 점화 특성을 이해하기 위해서 연소시험을 수행하였다. 최종적으로 지상 시험을 통해 킥모터 추진제를 점화시키기에 충분한 에너지를 공급할 수 있다는 것을 검증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.962-965
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• 2005

A high intensity progressive wave tube is installed at Korea Aerospace Research Institute (KARI) for acoustic environmental tests. The test facility has 700 mm x 800 mm cross-sectional area, and provides acoustic environment of 165 dB over the frequency range of $25Hz{\sim}10,000Hz$. The facility consists of a 6 m long acoustic wave tube, acoustic power generation systems, gases nitrogen supply systems, and acoustic control systems. This paper describes how the basic parameters of the facility and power generation systems are controlled to meet the requirement of the test. The shape and length of the tube has been designed by using the size of test objects and the wave propagation characteristics of the tube. The capacity of acoustic power generation systems is determined by the energy conversion of acoustic wave and the efficiency of acoustic modulators. Moreover, the paper introduces test run results of the tube. Overall of 163dB has been generated by using the test facility.

• 한국환경과학회지
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• 제27권6호
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• pp.467-475
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• 2018

The lifetime of the electrode is one of the most important factors on the stability of the electrode. Since the lifetime of the DSA (Dimensionally stable anode) electrode is long, an accelerated lifetime test is required to reduce the test time. Beacuse there is no basis or standard method for accelerated lifetime testing, many researchers use different methods. Therefore, there is a need for basis and methods for accelerated lifetime testing that other researchers can follow. We designed a reactor system for accelerated lifetime testing and planned specific methods. Reactor system was circulating batch reactor. Reactor volume and cooling water tank were 12.5 L and 100 L, respectively. Electrode size was $2cm{\times}3cm$ (real electrolysis area, $5cm^2$). In order to maintain the harsh conditions, accelerated lifetime test was carried out in a high current density ($0.6A/cm^2$) and low electrolyte concentration (NaCl, 0.068 mol/L). Maintaining a constant temperature was an important operation parameter for exact accelerated lifetime test. As the accelerated lifetime test progressed, the active component of electrode surface was consumed and desorption occurred. At the point of 5 V rise, corrosion of the surface of the base material(titanium) also started.

• 한국지반공학회논문집
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• 제33권12호
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• pp.127-139
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• 2017

고양 지역의 화강 풍화암 지층을 대상으로 시추조사 및 다양한 현장 시추공 시험(프레셔미터시험, 공내전단시험, Downhole test, Suspension PS 검층, 밀도검층)을 수행하였고, 채취한 풍화암 코어시료에 대한 X선 형광분석을 실시하여 풍화도를 평가하였다. 현장 시추공 시험 결과로부터 변형계수, 전단강도 정수, 전단파 속도 등을 평가하였고, 심도에 따라 각 지반특성 값이 증가하는 경향을 확인하였다. X선 형광분석을 통해 산정한 화학적 풍화지수는 심도에 따라 풍화도가 감소하는 일반적인 경향을 나타냈으며, 대표적 풍화지수인 VR과 풍화암의 지반특성과의 관계를 분석하였다.

• 영어어문교육
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• 제7권1호
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• pp.89-112
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• 2001

The purpose of this study is to verify the effect of the method of English teaching and learning through the student-centered environmental instruction. I've been skeptical about the traditional instruction, which is composed of the teachers-centered instruction, because of the lack of creativity. Until now, I've always wished to have an alternative method that can be substituted for routine's style. To achieve it, I selected 90 students from 2 classes, in the 3rd year at a girls' high school in Chungnam as the subject of study. I divided them into two groups, the student-centered environmental instruction and the teacher-centered traditional instruction. The tools used in this study are a preliminary English achievement test, a self-directed learning attitudes test and two teaching plans. For this test, a high school text book was assigned. I have treated 20 times of the test each for two groups using two types of teaching-learning plans which I made for this purpose. To verify the hypotheses after administrating the test, I selected t-verification for post test result. Based on this test result, I could conclude that there was a significant improvement of English proficiency and a change in the self-directed learning attitudes; also the student-centered environmental instruction is more effective than teachers-centered instruction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.748-753
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• 2008

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurisation causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. Bi-directional load tests using O-cell are now becoming common practice around the world, particularly where the loads to be applied are high or where it is not convenient to perform top-down loading tests. In the study, calculate ultimate capacity of bi-directional load test using FEM and beam on elasto-plastic foundation theory.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권4호
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• pp.147-155
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• 2007

Mobile air conditioning systems work under widely changing operating conditions. To understand the system behavior under such dynamic conditions, a test facility that can impose transient loads as well as conducting dynamic measurements is needed. To test mobile air conditioning systems including their dynamic performance under various drive cycle patterns without using full scale vehicles in a wind tunnel, a new test facility, called "dynamic simulator," is described. It can replicate real vehicle operating conditions by interacting with the system being tested based on the measured system performance and subsequently adjusting the air properties returning to the test system based on the results of a numerical cabin model. A new dynamic simulator has been designed, constructed, and verified for performing dynamic tests. It was successful in controlling the temperature and relative humidity of the air returning to the test unit within ${\pm}0.7^{\circ}C$ and ${\pm}4%$ of their respective intended values. The verification test under the New European Driving Cycle demonstrated that detailed transient behavior of the mobile air conditioning system could be measured by using this dynamic simulator.

• 한국물환경학회지
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• 제22권6호
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• pp.1119-1122
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• 2006

Aeration by using diffusers usually requires approximately 50~90% of the total electricity needed to operate WWTP (WasteWater Treatment Plant)s. Accurate evaluation of the oxygen transfer efficiency for an aeration system, and recommendation of a better alternative may help saving WWTP operational costs. Appropriate techniques and methods to achieve this purpose have not been introduced in Korea. In this study, in-process analysis was performed for a coarse bubble aeration system by the off-gas method to evaluate its applicability in Korea. To accomplish this analysis, an off-gas test, unsteady-state clean water test and steady-state off-gas column test was conducted and comparisons to other aeration systems were made. The ${\alpha}$ and the F estimated from the results of the unsteady-state clean water test and the steady-state off-gas column test were 0.61 and 0.90 respectively in a coarse bubble aeration system. The comparison of P.E tube diffusers laid out single spiral roll and ceramic dome diffusers laid out full floor coverage showed that the oxygen transfer efficiency of the coarse bubble aeration system was less than or similar to other aeration systems. But, airflow rates per unit area were 4~5 times greater than other aeration systems. In regards to the oxygen transfer efficiency for airflow rates per unit area, a retrofit to higher efficiency diffusers was urgently needed. This study showed proved that off-gas methods can apply to evaluate diffuser performances to estimate operating factors and to compare other aeration systems in Korea.

• 한국과학교육학회지
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• 제28권5호
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• pp.453-463
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• 2008

이 연구에서는 Draw-An-Environmental-Scientist-Test(DAEST)를 이용하여 학생들의 환경과학자와 환경과학자가 하는 일에 대한 인식과, 환경과학자 그림을 그리는데 영향을 미친 요인을 조사했다. 서울시 소재 일반계 고등학교 3개교에서 1학년과 2학년 학생 413명을 대상으로 DAEST를 실시했다. 연구 결과, 학생들의 환경과학자에 대한 이미지는 과학자의 정형적인 이미지와는 다르게 나타났다. 학생들의 그림에는 환경과학자의 나이와 성의 특징이 뚜렷하게 나타나지 않았다. 또한, 대부분의 학생들은 환경과학자를 야외에서 실험기구와 노트북 컴퓨터 등을 이용하여 환경오염과 관련된 데이터 수집을 하는 사람으로 인식했다. 한편, 학생들은 환경과학자에 대한 그림을 그리는데 영향을 준 요인으로 대중매체, 학교교육, 인터넷 등을 제시했다. 환경과학자와 환경과학자가 하는 일에 대한 인식 및 인식에 영향을 미친 요인은 학생들의 학년과 성에 따라 다르게 나타났다. 이에 대한 교육적 함의를 논의했다.