• Journal of Distribution Science
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• v.6 no.2
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• pp.5-19
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• 2008

This study aims to provide the present general state of basic data about refrigeration and freezing warehouses scold storages because basic data about refrigeration and freezing warehouses are insufficient and imperfect at the moment. Research contents include the present general state of cold storages such as sales amount, capital(money invested), storage possession state by type, keeping area, cold storage facility capacity, and facility state such as existence of rack, building structure and floor height, and possessed facility state. According to research results, it was found that 86.7% of refrigeration and freezing warehouses are located in the capital region and Busan region in terms of regional distribution, and the average keeping area was found to be bigger in these two regions than that of other regions. In addition, the research shows that more than 80% of companies possess bonded warehouses and there was no big difference in the size and capacity of refrigeration and freezing warehouses. Regarding building structure, most of them were found to be reinforced concrete. However, only 25% of companies installed racks, but there was no statistical significance between existence of rack and the amount of capital and sales. Possessed facilities were found in the order of freight elevator, information system and dock. When it comes to cargo gear, companies were found to possess 9.1 units of forklift and 2.2 units of reach stacker in average. This research is expected to lay a basis for investigating, predicting and developing the local cold storage industry, and more detailed studies will be needed in the future.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.2
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• pp.287-298
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• 1993

In this study, generation characteristics and distribution situation of the animal fat residue were investigated to identify it's management problems and to propose alternatives for the recycling and final disposal. Generation sources were the meat distribution net-work including about 170 slaughterhouses, 280 meat-packing plants, thousands of meat shops and restaurants etc. The daily total amount of the animal fat residue is about 700 ton/day. More than 60% of the generation sources were concentrated in Seoul metropolitan area. The residue was collected by about 300 men using old-fashioned devices like handcarts, bike and auto bike, transported to the recycling plants by about 60 collection agencies. The residue was processed to produce by-products such as grease, tallow, animal feed ingredient in the recycling plants. At present, however, a great number of unlicensed, and mostly small rendering processors without having pollution control facilities do the unlawful business. These small, old fashioned and unorganized businesses are creating environmental problems by disposing the waste in improper ways such as open burning and dump. Improvement of the distribution network, the large-scale plants, and the estabilishing proper infrastructures were suggested to overcome the problems for the sound fat residues reprocessing industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.200-207
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• 2017

3D printing is making a huge difference to existing industries and is beginning to be applied in the field of construction. 3D printing construction differs from existing construction techniques. Therefore, new construction processes need to be developed. In particular, the accurate construction duration is linked directly to a successful project. A method for estimating the construction duration for 3D printing construction is necessary. In this study, a 3D printing construction process and duration estimation method were derived to prepare for the future introduction of 3D printing in construction. The scope of the study was assumed to be 3D printing equipment capable of pouring concrete, and limited to a frame structure construction. The developed construction period estimation method was applied to the virtual test model. As a result of applying the test model, the construction duration was shortened by approximately 50% compared to the existing construction technique. The method of estimating the construction period developed in this study can be applied to 3D printing constructions in the future and help establish a business plan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.384-391
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• 2020

An annual average of more than 100 casualties occur on construction sites designated by the occupational safety and health law despite the safety assessment regulations from Korea Occupational Safety & Health Agency. Even if those sites involve more harmful or hazardous work than other sites, the result creates doubt regarding the effectiveness of the safety assessment regulations. The safety of construction sites is difficult to maintain continuously and instantly because ofthe variability in the construction industry despite inspecting workers, equipment, and facilities by managers. Many discussions on how to utilize BIM have been made to improve the productivity of construction projects, and BIM-based modeling and simulation would bring many benefits to safety. This study examined the hindrance factors of field utilization of the safety assessment regulations through a research literature survey, disaster situation analysis and questionnaire, and suggests the necessity of the application of BIM that enhances the effectiveness of safety assessment regulations by identifying the relationship between the hindrance factors and the function of BIM.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.3-4
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• 1999

최근 산업이 고속도화, 고능률화 및 고정멸화의 추세로 발전함에 따라 우수한 내마모성, 인성, 고온 안정성 및 내구성을 갖는 공구 및 금형을 요구하게 되었다. 그러나 이와같은 성질들은 어떤 단일 재료에서는 얻을 수 없으며 적당한 기판공구나 금혈위에 내마모성 보호피막을 coating함으로 비교적 저렴하게 얻을 수 있다. 화학증착법으로 TiC, TiN등을 증착시킬때에는 $1000^{\circ}C$정도의 반응온도가 필요하며 이러한 증착온도는 모재가 초경합금일때는 문제가 안되나 강재일 경우 모재의 연화와 칫수변화의 문제를 야기시킨다. 최근에는 플라즈마를 사용하여 증착반응온도를 $550^{\circ}C$ 이하로 낮추는 플라즈마 화학 증착볍(PACVD)이 대두되고 있다. 그러나 이 방법어서 는 뚱착하려는 금속원소가 TiCl4의 형태로 공급되고 있으므로 생성된 층이 염소를 포함하고 있다. 이 층에 잔존하는 염소는 층의 기계적 성질을 저하시키고 층내의 stress를 유발시킨다. 또한 HCI개스의 생성으로 인하여 펌프 및 장비의 부식이 촉진 된다 이러한 결점을 극복하기 위하여 금속유기화합물 전구체(metallo-organic precursor)로 $TiCl_4$를 대체하고자 하는 연구가 활발하게 진행되고 있으며 본 연구실에서 이에 대하여 연구한 결과를 소개하고자 한다. diethylamino titanium을 전구체로 사용하여 $H_2,\;N_2,\;Ar$분위기하에서 pulsed d.c.를 사용하는 MO-PACVD에 의하여 $150~250^{\circ}C$의 저온에서 Al 2024 기판에 TiCN층 형 성을 하였다. 전구체 증발온도는 $74~78^{\circ}C$의 온도범위어야 하며 고경도의 코탱층은 54% duty, 14.2kHz, 450V의 조건에서 얻어졌으며 duty, 주파수, 전압이 증가함에 따라 경도는 저하되었다. 이때의 표면 morphology를 SEM으로 조사한바 dome structure가 크게 발달되었음을 알 수 있었다. 본 실험의 온도 범위내에서 얻은 TiCN 증착반응의 활성화에너지는 7.5Kcal/mol이었다. 증착된 TiCN층은 우수한 내마모섣을 나타내었으며 스크래치테스트 결과 17N의 엄계하중을 나타내었다. 본 연구에서 변화 시킨 duty, 주파수, 전압의 범위에서는 층의 밀착력은 크게 변화하지 않았다. titanium isopropoxide를 전구체로 사용하여 Hz, Nz 분위기하에서 d.c.를 사용하는 MO-PACVD에 의하여 Ti(NCO) 코팅층을 SKDll, SKD61, SKH9 공구강에 형성시키는 공정을 개발하였다. 최적의 Ti(NCO) 코탱층을 얻기 위해 유입전구체 부피%의 양은 향착압력의 5%를 넘지 않아야 되고 수소와 젤소 가스비가 1:1일 때 가장 높은 코팅층의 경도값을 나타내었다. 수소와 질소 가스비가 3:7일 때 TiFeCr(NCO)의 복화합물 코팅층이 형성됨을 알 수 있었고 500t의 증착온도에서 얻은 Ti(NCO) 코팅층이 높은 경도값과 좋은 내식성을 나타내었다. 또한 이와같은 Ti(NCO) 코팅공정과 본 실험실에서 개발한 확산층만 형성시키는 plsma nitriding 공정을 결합하여 복합코탱층을 형성하였는데 이 복합코팅층은 고경도와 우수한 내마모성, 내식성 뿐만 아니라 10)N 이상의 뛰어난 밀착력을 나타내었다. 현재 많이 사용되고 있는 PVD법은 step coverage가 좋지 않은 점과 cost intensive p process라는 단점이 있다. MO-PACVD법은 이러한 문제를 해결할 수 있는 방법으로서 앞으로 지속적인 도전이 요구되는 분야이다.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.109-122
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• 2018

Domestic LPG meters are being tested for LPG quantification in accordance with the "Measures Act". The LPG meter is re-tested every three years in accordance with the "Enforcement Decree of the Measures Act". The maximum permissible error within the test is within ${\pm}1.0%$, and the tolerance is within ${\pm}1.5%$. For the quantitative measurement of LPG, a hydrometer for LPG, a balance, and a pressure vessel are used. The volume of LPG varies in depending on the temperature and pressure. The current quantitative measurement method of LPG requires the measurement of temperature, pressure and density in order to determine the volume of LPG, respectively, and some equipments are needed accordingly. Coriolis mass flowmeter, on the other hand, measure the mass flow, density and temperature at the same time, and can be converted and calculated to the required values using a computer program, also it is widely applied in the industrial field. In this study, the volume of LPG was measured using a Coriolis mass flowmeter as a basic study of LPG quantitative measurement. In addition, it is shown that it is possible to apply for the LPG quantitative measurement using the Coriolis mass flowmeter by comparing it with the conventional LPG quantitative measurement method.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.141-146
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• 2019

Radiation sources used in the field of industrial non-destructive pose a risk of exposure due to ageing equipment and operator carelessness. Thus, the need for a safety management system to trace the location of the source is being added. In this study, Monte Carlo Simulation was performed to analyse the angle dependence of the unit-cell comprising the line-array dosimeter for tracking the location of radiation sources. As a result, the margin of error for the top 10% of each slope was 5.90% at $0^{\circ}$, 8.08% at $30^{\circ}$, and 20.90% at $60^{\circ}$. The ratio of the total absorbed dose was 83.77% at $30^{\circ}$ and 53.36% at $60^{\circ}$ based on $0^{\circ}$(100%) and showed a tendency to decrease with increasing slope. For all gradients, the maximum number was shown at $30^{\circ}$ No. 9 pixels, and for No. 10, there was a tendency to drop 7.24 percent. This study has shown a large amount of angle dependence, and it is estimated that the proper distance between the source and line-array dosimeters should be maintained at a distance of not less than 1 cm to reduce them.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.113-121
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• 2019

The death rate of industrial accidents per 10,000 people in Korea is two to three times higher than that of major countries. Falling accidents at the construction site happened to have caused the most deaths. Analysis of existing research and measures by national institutions showed that the industrial accident management concentrated on falling accidents was insufficient and the seasonal safety management measures were not enough. There is thus the need for research that provides detailed and enough information on falling accidents. This study, therefore, aims to overcome the limitations of existing research and safety management accident response using a methodology that provides the necessary information for the prevention of fall accidents by deriving seasonal crash characteristics of the construction site. In order to provide enough information, 387 cases of seasonal construction site falling were collected, which describes the causal relationship of accidents. Text mining using principal component analysis and cluster analysis was carried out. The analysis showed that: In the spring, snowfall and unreasonable operation of equipment including lifts were the major cause. In summer, most accidents were caused by form, insufficient safety inspection, and installation work. In autumn, weather factors such as wind and typhoon were the cause. In winter, material transportation, exterior wall work, and ignore safety precautions were the cause of the crash.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.13-24
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• 2021

Tunnel boring machine (TBM) is widely used for tunnel excavation in hard rock and soft ground. In the perspective of TBM-based tunneling, one of the main challenges is to drive the machine optimally according to varying geological conditions, which could significantly lead to saving highly expensive costs by reducing the total operation time. Generally, drilling investigations are conducted to survey the geological ground before the TBM tunneling. However, it is difficult to provide the precise ground information over the whole tunnel path to operators because it acquires insufficient samples around the path sparsely and irregularly. To overcome this issue, in this study, we proposed a geological type classification system using the TBM operating data recorded in a 5 s sampling rate. We first categorized the various geological conditions (here, we limit to granite) as three geological types (i.e., rock, soil, and mixed type). Then, we applied the preprocessing methods including outlier rejection, normalization, and extracting input features, etc. We adopted a deep neural network (DNN), which has 6 hidden layers, to classify the geological types based on TBM operating data. We evaluated the classification system using the 10-fold cross-validation. Average classification accuracy presents the 75.4% (here, the total number of data were 388,639 samples). Our experimental results still need to improve accuracy but show that geology information classification technique based on TBM operating data could be utilized in the real environment to complement the sparse ground information.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.77-88
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• 2006

In this study, the lateral behavior of Pile-Bent structures subjected to lateral loading was evaluated by a load-transfer approach. An analytical method based on the Beam-Column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic and yielding) and $P-{\Delta}$ effect. Special attention was given to the lateral deflection of Pile-Bent structures depending on different soil properties, lateral load, slenderness ratio based on pier length and reinforcing effect of casing. From the results of the parametric study, it is shown that the increase of lateral displacement in a pile is much less favorable for an inelastic analysis than for an elastic analysis. It is found that for inelastic analysis, the maximum bending moment is located within a depth approximately 3.5D(D: pile diameter) below ground surface, but within 1.5D when $P-{\Delta}$ effect is considered. It is also found that the magnitude and distribution of the lateral deflections and bending moments on a pile are highly influenced by the inelastic analysis and $P-{\Delta}$ effect, let alone soil properties around an embedded pile.