A Comparative Analysis on Export Complexity and Export Technology Structure of Mechanical and Electrical Products between China, Japan and Korea

Using the method of export complexity index, this paper calculates the export trade structure and technology content of mechanical and electrical products between China, Japan and South Korea from 2000 to 2016 based on the 6-digit code of UN COMTRADE database, and examines the differences between them in export technology complexity and export technology structure. The results show that although the export technology complexity of China’s mechanical and electrical products has been improved to some extent, it is still not high. Among the mechanical and electrical products exported by China, there are more products with low complexity and medium complexity, while Japan’s products with high complexity are obviously more than China’s, and Korea’s products with low complexity are less than China’s. Based on this, this paper puts forward some suggestions on upgrading the export technology structure of China’s mechanical and electrical products.


Introduction
China, Japan and South Korea are the three most powerful and active economies in East Asia, and they are also typical representatives of developing countries, developed countries and newly industrialized countries in East Asia. The trade relations between China, Japan and South Korea are inseparable and important trade among the three countries has always been a topic of concern to scholars.
In recent years, the focus of discussion on China's export trade has gradually shifted from export scale to export structure and product quality. The index system to measure a country's trade technology structure based on degree of Sophistication has become a hot topic in the field of international trade [1] [2] [3] [4]. In China, Yao and Zhang [5], who first used this method, measured the technology content of China's export processing industry from 1997 to 2002, and finally concluded that the decline of domestic technology content of China's export products may be only a temporary phenomenon. From then on, Zhu et al. [6] analyzed the changes of the technological structure of China and India's export products, and found that both countries' export technology level and technological height have increased significantly, but overall, the improvement degree of China's export technological structure is much higher than India's.
There are complementarities in the structure of export trade and the technological level of trade products between the two countries. Based on the export data of metal products from 52 economies in the world from 1993 to 2006, Huang et al. [7] calculated the export complexity and constructed a model. It is believed that the driving force of China's export complexity has changed from export-driven to economic growth-driven. Fan and Chang [8] analyzed the technical structure of import trade of China, Japan and South Korea in many aspects by using the measurement method of the technical structure of export trade.
They believe that compared with the structure of Japanese and Korean import products, China's import trade shows a special structure with a large proportion of products at both ends and a small proportion of intermediate products. Guo and Yang [9] measured the export complexity of four high-tech industries: medicine, computer and office equipment, electronic and communication equipment, medical equipment and instruments. They concluded that the export complexity of high-tech manufacturing industry in China mainly comes from economic growth rather than technological innovation. Huang and Zhang [10] summarized the research progress on the definition, measurement, anomaly and internal mechanism of export complexity in foreign literature. He and Tian [11] calculated the export complexity of agricultural products of China, Japan and South Korea from 2000 to 2010, and found that Japan's technological structure is still the highest, followed by South Korea. There is still a gap between China and Japan and Korea. Tong [12] calculated the export complexity of high-tech products from China, Japan and Korea based on HS4 code, and analyzed the technical characteristics and development trend of high-tech products from China, Japan and Korea. It can be seen that mechanical and electrical products play an important role in the study of the trade structure and evolution trend of the three countries. Many people think that China has become a big trading country in mechanical and electrical products, but is it a powerful trading country in mechanical and electrical products? Compared with Japan and Korea, how about the export technology content of China's mechanical and electrical products? What's the difference between them? There is a lack of research on these issues in the literature, a few of which are related to agricultural products and high-tech products, but they are only based on HS4-digit coding to measure the complexity of export technology, and lack of more detailed product-level analysis.
To this end, this paper will use the method of export complexity index to measure the changes of export technology content of mechanical and electrical products between China, Japan and South Korea from 2000 to 2016 based on UN COMTRADE 6-digit data, and compare the differences of export technology structure between China, Japan and South Korea. The mechanical and electrical products studied in this paper include seven categories of HS84~HS90 products [13]. There are 1046 kinds of mechanical and electrical products using HS six-digit coding. Compared with the current research on mechanical and electrical products based on HS four-digit coding, more specific product level information can be obtained.  Figure 1). It can be seen that China, Japan and South

Analysis on the
Korea play a decisive role in the export of mechanical and electrical products in the world.
China has the lowest starting point in the development among the three  After 16 years of development, it has only increased by about 1.2 times. It has been in a stable state. This shows that Japan's electromechanical products industry started earlier and its technology has developed to a higher level. It can be seen that in 2009, due to the impact of the economic crisis, the export volume of mechanical and electrical products of the three countries has declined, of which South Korea declined the least, indicating that it was the least affected by the economic crisis.

An Overview of the Export of Mechanical and Electrical Products between China, Japan and Korea
The trade volume of mechanical and electrical products between China, Japan and Korea is also increasing year by year. The total trade volume of mechanical and electrical products between the three countries in 2000 was only US$63.9 billion, while in 2016 it rose to US$290.2 billion, an increase of 4.5 times. Figure 2 shows that in 2016, the trade volume of mechanical and electrical products between

Construction of Export Complexity Index
The technology content of products is reflected by R&D cost, but the cost of R&D in industry and product level cannot be accurately calculated. Hausmann [1] proposed the concept of complexity to measure the technology content of products. Hausmann et al. [1] combined per capita income with export, constructed export complexity index-EXPY index, which was used to analyze the technology content of export products, industries or exporting countries. The calculation of the index can be carried out in two steps.  At the same time, it also shows that Japan's production of low-tech complex products is very small. According to this table, Japan mainly depends on the export of high-tech products to some developing countries, including China. It uses a large number of labor forces for processing and production.  relatively late, and there was no export of these two products before 2006. However, they developed rapidly and could export a large number of products with high complexity in a few years. It is not difficult to see the role played by China, Japan and Korea in international production from the above table. Because of the relatively backward technology level, China imports a large number of high complexity mechanical and electrical products from foreign countries, while exporting low and medium technology complex mechanical and electrical products with the advantage of human cost. This kind of trade not only promotes the trade between China, Japan and South Korea, but also helps China learn advanced technology from other countries.

Evolution of Export Complexity of TOP2 Mechanical and Electrical Products in China, Japan and Korea
At the same time, we calculated the PRODY values of all 1046 products, and according to the relative value segmentation method [14], we divided the technical complexity of mechanical and electrical products into five categories: higher, high, medium, low and lower. Because the research object is too large, we cannot list them one by one, so Table 2 only lists the product codes with relatively large export volume under each category. Table 2 shows that higher-tech complexity and lower-tech complexity products are relatively few, and the overall distribution is "small at both ends and large in the middle". Some products have high technical complexity, such as HS90 (optical, photographic, film, metrology, inspection, medical or surgical instruments and equipment, precision instruments and equipment; parts and accessories of the above items), HS8704 (with a spark-ignited piston internal combustion engine), HS8467 (parts for other portable electric tools), HS8439 (machine parts for making or finishing paper and cardboard), HS8448 (looms and auxiliary machines using other parts and accessories), HS8440 (other book binding machines), HS8411 (parts for turbojet or turboprop engines), HS8430 (non-self-propelled tamping or compacting machinery), HS8802 (aircraft and other aviation), HS8535 (circuit fuse). China should strengthen research and investment in these industries in order to obtain higher value-added returns. Table 3 shows the distribution of product complexity of China, Japan and South Korea in the top 100 export volumes in 2016. According to the statistical results,

A Comparative Analysis on Export Structure of Mechanical and Electrical Products between China, Japan and Korea
China's export of mechanical and electrical products is dominated by low and medium complexity products, with no high and higher complexity products, and there is a big gap with Japan and South Korea. The export of mechanical and electrical products in Korea is similar to that in Japan, but the export of Table 3. Complexity distribution of TOP100 exports of mechanical and electrical products from Japan and Korea. products with high complexity still lags behind that in Japan, and there are a certain number of products with lower complexity.  The proportion of low complexity products in Korea is larger and rising year by year. The proportion of medium and high complexity products is equal to that in China. The proportion of lower complexity products in Japan is very small, while the proportion of medium complexity products is steadily increasing year by year. The proportion and growth trend of high complexity products are significantly higher than those of China and Korea. The proportion of products with higher complexity in the three countries is relatively small, but the proportion of Japan is higher than that of China and Korea. Korea accounts for a larger proportion of products with higher complexity than China.
It can be concluded that Japan still shows obvious advantages in the overall technical content of mechanical and electrical products, which is superior to China and Korea. The overall technical content of China and Korea is basically the same, but the overall technical level of Korea is still higher than that of China. Since China's entry into WTO, a considerable part of the export of mechanical and electrical products belongs to processing trade. Most of Chinese enterprises are engaged in the middle and low-end processing of mechanical and electrical products, with low added value.
In terms of technology structure, the optimization degree of technology structure of mechanical and electrical products in China and Korea is obviously weaker than that in Japan, and that of Korean mechanical and electrical products is better than that of China. China's poor export technology structure is attributed to the large export volume of products with low technology and medium and low technology content. Japan has shown obvious advantages in the export of high-tech products. In the bilateral trade of mechanical and electrical products, China and Korea have a lot of low-complexity mechanical and electrical products export, so there is a certain degree of competition in low-tech products. However, the two sides have shown complementarity in the export of high-tech mechanical and electrical products. This shows that, compared with Japan and Korea, although China occupies a dominant position in low-tech products, it is obviously weak in medium-high and high-tech products. If the technology level of a country is judged largely by the quantity of high-tech products it produces or exports, then the overall technology level of Chinese manufacturing is lower than that of Japan and Korea. In addition, although South Korea is still weaker than Japan in general, it has a competitive relationship with Japan in low and medium technology content products.

The Evolution of the Technical Complexity of the Overall Export of Mechanical and Electrical Products of China, Japan and Korea
This paper chooses the EXPY value of the top 25 countries in the world (which account for 90% of the world's total exports) as the world average, and uses it as a reference frame to study the evolution of the overall export technology complexity of mechanical and electrical products in China, Japan and Korea. Figure   4 shows

Conclusions and Suggestions
This paper finds that although the export technology complexity of China's mechanical and electrical products has been improved to some extent, it is still not high enough. Among the mechanical and electrical products exported by China, there are more products with low complexity and medium complexity, while Japan's products with high complexity are obviously more than China's, and Korea's products with low complexity are less than China's. From the perspective of technology content, the gradient level between China and Korea is relatively small, and the gap between China and Japan is large. Based on the above analysis, this paper puts forward the following suggestions to promote the upgrading of export technology content of mechanical and electrical products in China. Continue to promote economic development and maintain stable economic growth. Per capita GDP plays a more direct role in promoting the export technology complexity of mechanical and electrical products, which has been shown in the calculation formula of export technology complexity. Per capita GDP is the embodiment of a country's comprehensive strength. The increase of per capita GDP means that the economy is in the growth stage. Enterprises are optimistic about the future and are willing to invest more resources to produce high-tech products. On the other hand, with the increase of per capita GDP, consumers' demand for high-tech electromechanical products increases. This can promote enterprises to produce mechanical and electrical products with higher technology content from the demand side to meet market needs. Therefore, we must continue to promote economic development and maintain stable economic growth.
Encouraging the introduction of more foreign-invested enterprises in high-tech mechanical and electrical industries. Many studies have confirmed the technology spillover effect of FDI. Local enterprises can learn and absorb the advanced technology and design capabilities of transnational investment me-